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Chapter 6

Army and Army Group
Defensive Operations


Reasons for Assuming the Defense
Operational Formation
Threats to the Defense
Priciples of OPFOR Defense
Information Warfare
Reasons for Assuming the Defense
Transition to Defense
Operational Formation and Tasks
Types of Defensive Action
Transition to Defense
Operational Formation and Tasks
Types of Defensive Action
Costs and Benefits
Successful Action and Survival of Encircled Groupings
Problems of Organization Within Encirclement

The OPFOR defines an army group or army defensive operation as the aggregate of operations and battles of subordinate units unified by a single concept and plan.1 Subordinate operations may involve--

  • First- and second-echelon maneuver forces.
  • Reserves.
  • Surface-to-surface missile (SSM) and artillery units.
  • Army group aviation.
  • Army aviation.
  • Airborne and heliborne units.
  • Electronic combat (EC) and reconnaissance units.
  • Air defense forces.
  • Naval and amphibious forces (on a coastal axis).

The combined arms concept is an integral part of the OPFOR approach to defensive operations.

Even when a given army group as a whole is conducting an offensive operation, it is likely that one or more subordinate armies may be executing defensive missions. The same is true of divisions within an army. This may be out of necessity, as when encountering a superior enemy force during the course of an offensive. However, it may also be in an economy-of-force role, to permit the OPFOR to establish a correlation of forces (COF) advantage on its main attack axes sufficient to ensure a higher probability of success there. The primary focus of OPFOR operational-level defensive planning is at the army level.


The OPFOR regards a defensive operation as a temporary measure conducted when successful offensive operations are not possible in a particular area. The purpose of the defense can be to--

  • Perform economy-of-force missions, allowing for concentration of superior forces along the main axis.
  • Hold key terrain.
  • Protect significant areas or installations.
  • Buy time.
  • Halt and repulse an enemy offensive.
  • Inflict maximum losses on the enemy.
  • Create the conditions for transitioning to offensive operations.

The ultimate goal of the defense is to wrest the initiative from the attacking enemy forces.


Army or army group defensive operations involve the use of operational maneuver and positional defense. The exact nature of the defense depends on whether the OPFOR establishes it in direct contact or out of contact with the enemy.

The army and army group deploy in a series of defensive lines and zones with alternate positions. However, the OPFOR does not intend these lines and zones for use in successive, positional, defensive battles. Prepared positions in depth provide protection and lines or areas for counterpenetration, but the basis of the defense is maneuver and counterstrike against enemy forces trying to reduce prepared defenses.

The OPFOR designs its defenses to be penetrated, but at a significant cost to the enemy in casualties, time, momentum, and disruption. This creates the optimum conditions for a counterstrike.2 The OPFOR then destroys the enemy.

For the OPFOR, the basic defense is a positional defense. A defense out of contact with the enemy allows for more extensive engineer preparation consisting of barriers, obstacles, and minefields throughout the depth of the position. However, the defensive concept is not completely static; it involves aggressive maneuver in concert with fixed defensive positions. Positional defenses weaken the attacker, allowing maneuver forces to deliver decisive blows into the enemy's flanks.

The OPFOR might use a maneuver defense when--

  • It can afford to surrender territory.
  • Forces are insufficient to conduct a positional defense.
  • Conditions are suitable for luring an enemy into an operational fire sack where the OPFOR can deliver decisive fire strikes and counterstrikes.

Reasons for Assuming the Defense

Defensive operations are essentially a temporary form of combat action. An army or army group assumes the defense when offensive actions are not possible (because of inadequate resources) or when they are undesirable (considering operational and strategic concepts). The following paragraphs describe the circumstances when an army or army group might act on the defensive.

A defensive operation may be merely a prelude to a decisive counteroffensive. At the beginning of a war, the OPFOR initially may have to meet superior enemy forces with a defensive action to prevent the enemy's seizure of important economic, administrative, and political centers. The defenders may also need to gain time for the mobilization, concentration, and deployment of strategic groupings.

Either at the beginning of a war or during the course of operations, an army or army group may transition to the defense after defeat. This might occur in a meeting engagement or in an offensive, or as a result of devastating nuclear or precision-weapon strikes.

In the course of offensive operations, an army or army group may transition to the defensive to repel an enemy counterattack that is too strong for a meeting engagement. If the enemy mounts a small-scale counterattack, the OPFOR response would be to place one or more divisions on the defense, while the rest of the army or army group continues the offensive.

After completing an offensive mission, an army or army group may assume the defensive because it has taken the designated strategic objective. The defense might also allow the army or army group to regroup and resupply before resuming offensive operations on its axis. A defense might cover the exposed flank of another strategic grouping of forces conducting an offensive in the theater.

Operational Formation

In the defense as well as the offense, the term operational formation refers to the basic organization for combat by an army or army group. The OPFOR is quite flexible in its organization for combat, which corresponds to the mission and the forces available. Figure 6-1 outlines the possible elements of operational-level defensive deployment within a series of defensive lines and zones.



Defended By

(Security Zone)

Brigades or Reinforced
Battalions from Army's 1st- or 2d-
Echelon Division(s)

Tactical Zone of Defense

Army 1st Defensive Line

Army Main Defensive Zone

Army's 1st-Echelon

Army 2d Defensive Line

Army 2d Defensive Zone

Army's 2d-Echelon
Division(s) or Combined Arms

Operational Zone of Defense

(Army 3d Defensive Line)

(Army 3d Defensive Zone)

Army's 2-Echelon Division(s) or
Combined Arms Reserve

Army Group 1st Defensive Line

Army Group 1st Defensive Zone

Army Group's Combined Arms
Reserve and/or 2d Echelon

(Army Group 2d Defensive Line)

(Army Group 2d Defensive Zone)

Army Group's 2d Echelon or
Combined Arms Reserve

Lines and zones in parentheses may or may not be present.

Figure 6-1. Operational formation for defense.


In the defense, as well as in the offense, armies and army groups have a first echelon and a second echelon and/or a combined arms reserve. The OPFOR achieves depth in its operational formation for defense by establishing a security zone (when possible) and a series of army and army group defensive lines. Behind each defensive line is a defensive zone, the depth of which largely depends on the number of division defensive positions employed within the zone. The main maneuver forces of the army or army group are within these zones. However, there are also spaces between defensive zones which often contain special reserves, command posts (CPs), missile units, and possibly detached defensive lines and positions. A typical distance of about 15 km between zones allows the possibility of establishing a security zone in front of the defensive line that forms the forward edge of each defensive zone.

An army may deploy in two or three defensive lines. The first army defensive line coincides with the forward edge of the defense; the last army defensive line (second or third) is the army defensive line. Behind its first-echelon armies, the army group deploys its second echelon and/or combined arms reserve in one or two army group defensive lines; the rearmost line (first or second) established by the army group is the army group defensive line.

The first army defensive zone is normally the main defensive zone; together with the army second defensive zone, it comprises the tactical zone of defense. Everything from the rear edge of the tactical zone of defense back to the rear edge of the army group's rearmost (first or second) defensive zone is part of the operational zone of defense; this includes the army's third defensive zone, if there is one.

The system of defensive lines and zones does not mean that OPFOR commanders conduct a static positional defense with all of their forces. Within the various zones, and sometimes between them, reserves and second-echelon forces have planned commitment lines. Should a penetration develop, they would assume blocking (counterpenetration) positions or initiate counterstrikes on these lines. The system of defensive lines and zones, and echelonment within zones, allows room and the necessary forces for maneuver. By dispersing forces laterally and in depth, it also reduces the vulnerability of its defending forces to precision weapon or NBC strikes.

Defending Forward

OPFOR defensive concepts emphasize the need to delay, defeat, or weaken the enemy offensive as far forward of the main defensive zone as possible. Reconnaissance troops attempt to locate enemy forces and determine enemy intentions. When possible, an army or army group establishes a security zone. An army's security zone may extend forward as far as 15 to 50 km. The depth of such a security zone depends primarily upon the forces, resources, terrain, and time available. The security zone delays, weakens, and deceives the enemy.

Using artillery, SSMs, helicopters, and aircraft, OPFOR commanders try to attack the enemy in concentration areas before an attack. The OPFOR conducts counterpreparatory fires to break up and disorganize enemy formations in advance of the main defense zone. Missile and artillery forces locate far forward in initial fire positions to strike the enemy as deeply as possible. They then fall back to planned primary and alternate firing positions in the main defensive zone.

Threats to the Defense

The OPFOR believes an enemy offensive (or counteroffensive) poses four threats to the viability of the defense: precision weapons, air power, armor, and airborne or heliborne landings.

Precision Weapons

Long-range, precision weapons can possess the destructiveness of small-yield nuclear weapons and use all-weather, deep-looking surveillance means for targeting. Their use can wear down the defender as he prepares defensive positions. By the time the enemy force reaches the forward edge of the defense, his precision weapons could have reduced the OPFOR to the point where it lacks the necessary COF to defeat the enemy attack. The enemy might also use precision weapons to interdict the second-echelon forces the OPFOR needs to conduct a counterstrike.

Air Power

Even without using nuclear weapons, potential enemies can deliver formidable firepower from the air. The development of air-delivered, long-range, precision weaponry is increasing this threat. To reduce the effectiveness of enemy air power, the OPFOR relies on thorough preparation of the defense, dispersion, air defense, and information warfare.


Modern armies base their offensive capabilities on masses of armored fighting vehicles. These possess high mobility, flexibility, firepower, and shock power. Thus, they can quickly exploit any weakness in the defense to generate operational maneuver into the defender's rear. Therefore, the maneuver of ground forces and the concentration of combat power at the decisive point within the defense is critical to defeating this capability.

Airborne or Heliborne Landings

Airborne or heliborne (or in coastal areas, amphibious) landings usually complement and aid armored thrusts. These landings threaten to undermine the OPFOR defense by disrupting its command and control (C2) and logistics systems and by seizing vital ground. Thus, the OPFOR's antilanding plan is an essential part of the overall defensive scheme.

Principles of OPFOR Defense

The basic principles for OPFOR defense are a response to the threats described above. These principles focus on making optimum use of the defender's capabilities and seizing the initiative from the attacking enemy forces.


The OPFOR makes the most thorough preparation that time allows. Preparation includes engineer work and the stockpiling of ammunition and other essential materiel. All OPFOR elements must be ready to withstand precision weapon, air, and artillery attacks. Second echelons and reserves must be protected against deep attacks.

Extensive obstacles can disrupt and canalized enemy armored attacks. Preparation of the first defensive line (zone) continues until the enemy attack begins. Preparation of subsequent lines (zones) continues as the OPFOR fights the enemy in forward zones.


The OPFOR defender cannot afford to rely on passive, positional defense; he must not surrender the initiative to the attacker. The more aggressive the defense, the more stable it is. Within the context of theater and army group defensive operations, respectively, army groups and armies can deliver attacks of limited goals and spatial scope but with important roles on decisive axes.

Preemption, an expression of continuous aggressiveness, is highly desirable, especially against enemy precision weapons and NBC-delivery systems. Altering an unfavorable COF at the last minute and disrupting the enemy's timetables by means of counterpreparatory fires also a key to success in conventional defense. Preemptive offensive operations by divisions, armies, or larger forces are also a possibility, even on a strategic scale.


A critical part of the defense is the maneuver of combat troops, both from secondary sectors and from the rear, to form concentrations either for counterpenetration or for counterstrikes. This avoids lengthy occupation of the counterstrike sector, which could result in heavy losses during the enemy's preparation. It also fulfills the need for anti-precision-weapon maneuver (that is, the frequent relocation of units to get out from under enemy strikes). Successful, timely maneuver increases the defender's power and makes it possible to defeat a superior enemy force.

Counterattacks and counterstrikes. Tactical-level counterattacks or operational-level counterstrikes are offensive actions designed to retake ground or destroy enemy penetrations. They are the basis of a successful defense. Ideally, the OPFOR launches the counterattack or counterstrike when--

  • The enemy has not yet disrupted the defense's stability.
  • The enemy has already committed his immediate reserves.
  • Interdiction has delayed or disrupted the entry of further enemy reserves into the battle.

The OPFOR prefers to launch counterattacks against a disrupted enemy penetrating force or when the enemy is transitioning to a hasty defense. This allows the OPFOR to seize the initiative from the enemy, forcing the enemy to respond to OPFOR actions. Commanders must, however, be sure of producing significant operational (or operational-tactical) results before initiating the counterattack. If the first echelon cannot achieve the counterpenetration, the commander must use second-echelon units or reserves for that role.

Counterpenetration. If the attacker has already succeeded in upsetting the stability of the defense and still has additional reserves within striking distance, the defending commander may choose not to counterattack. Rather, he may use his own second-echelon or reserve forces to replace elements of the first echelon and block any further enemy advance. This would allow the senior commander to make more decisive counterstrikes with his reserves. The OPFOR's aim is not merely stop the enemy, but to destroy him and create conditions favorable for the OPFOR's own attack. In addition to the second echelon and reserves, the commander may use airborne elements or heliborne mechanized infantry troops for counterpenetration tasks.

Reconnaissance. Success in the defense requires continuous and aggressive reconnaissance into the enemy's depth. Determining the enemy's main axes, the locations of his force groupings, and his timetable are essential to preemptive actions. Accurate information gained by thorough reconnaissance gives the commander the ability to disrupt approaching enemy forces with long-range fire, timely maneuver, and damaging spoiling attacks.

Deep battle and deep operations. Even in defense, there is a place for deep attacks to disrupt, damage, and delay the attacker. The OPFOR does not limit these deep attacks to air and precision-weapon strikes. In friendly territory, the OPFOR attempts to organize partisan movements. Partisans carefully coordinate with main forces and may receive reinforcement from regular troops.


The OPFOR uses all means of fire at its disposal to begin engaging the enemy as early as possible, continuing throughout the depth of the defense. The goal is to mass the effects of weapon systems, although the weapon systems themselves may remain widely dispersed. OPFOR planners must seek to mass fires not only at the decisive point but at the decisive time while economizing forces and fires in other areas. Flexibility to shift fires as conditions change is an important aspect of this principle. To the extent that they are available, precision weapons offer the OPFOR the ability to achieve decisive effects without massing forces or fires in the traditional sense.


Not all defensive actions have a maneuver character. The OPFOR must hold some key areas and lines to ensure the stability of the defense, disrupt the enemy, and gain time to maneuver units from unthreatened sectors or the rear. Defending units do not have the right to withdraw without orders from the senior commander. They must hold tenaciously. This applies even if they are encircled or have lost communications with higher or adjacent units. Generally, attempts to break out of encirclement equate to the effective loss of the unit as a fighting entity. It also has an adverse effect on efforts to stabilize the defense in depth or to counterattack.

The mix of positional and maneuver defense varies from sector to sector. In some areas, the commander combines the retention of occupied lines and zones with local counterattacks. In other areas he may decide to use a maneuver defense. He may also decide to use a combination of the two. Methods can vary according to the mission, the terrain, forces available, and other criteria. As a result, operations often develop in a nonlinear fashion.

Information Warfare

The OPFOR commander counts on information warfare (IW) to provide an information advantage during defensive operations. Planners develop a detailed IW plan with two primary goals: denying information or misleading the enemy concerning the organization, location and intentions of the defense. IW objectives include the following:

  • Disrupt or destroy enemy C2.
  • Allow the OPFOR to seize, retain, and exploit the initiative.
  • Place OPFOR strengths against enemy weaknesses.
  • Conceal friendly forces.
  • Cause friendly forces to appear stronger or weaker at critical points.
  • Portray a false disposition of forces.
  • Portray false levels of preparation, readiness, and morale.

The following elements of IW are significant contributors to the defense.

Electromagnetic Spectrum Operations

Electromagnetic spectrum operations (ESO) in the defense focus on disrupting enemy C2, degrading enemy electronic systems, and protecting OPFOR electronic assets. As in the offense, the OPFOR assigns various friendly and enemy C2, communications, computer, and intelligence links a priority based on the expected impact of their disruption, as well as the phase of the operation.

The OPFOR is likely to use airborne jammers in the defense to ensure the survivability of friendly air platforms and to help maintain at least local air superiority. Air defense jammers and related systems have increased emphasis when the enemy makes heavy use of air power in support of offensive operations.

Electronic protection measures ensuring the OPFOR's use of electronic systems are critical to effective coordination and conduct of the defense. In addition to those measures conducted as part of the protection and security effort, the OPFOR may use a jamming screen during critical phases of the defense to protect vital communications from enemy intercept and jamming.

The OPFOR gives considerable attention to the selection of specific targets and the time and location for attacking them. For example, the jamming of fire support nets supporting the enemy's fire preparation, prior to the actual assault on the OPFOR defensive positions, can reduce the effectiveness of fire. However, as the assault on the OPFOR defense begins, the priority is jamming of enemy maneuver unit C2 nets to prevent a well-coordinated attack.

In the event of an enemy penetration, ESO support of the OPFOR response is especially critical. Objectives include disrupting the communications between the penetrating force and the main body, as well as preventing or limiting support (such as fire support and aviation) from the main body.


During the defense, IW-related destruction measures focus on destroying enemy assets critical to the control of the offensive. As in the offense, indirect fire, ground, and air attack all contribute to the effort. Specific targets can vary based on location and time, but typical high-priority targets include--

  • Precision weapon systems.
  • C2 nodes and facilities.
  • Artillery, tactical aviation, and air defense systems.
  • Reconnaissance, surveillance, and target acquisition systems.

Special emphasis is on destruction of enemy reconnaissance, surveillance, and target acquisition capabilities prior to the attack on OPFOR defensive positions. Once the attack begins, enemy C2 nodes responsible for the planning and conduct of the attack, along with supporting communications, become priority targets. If the OPFOR destroys enemy C2 nodes prior to the attack, the enemy may have time to reconstitute his control. However, targeting the same nodes once the enemy has committed his forces to the attack can cause a far greater disruptive effect.

Protection and Security

Reconnaissance activities focus on identifying enemy main forces and their objectives, primarily the location of the planned attack and penetration. Winning the counterreconnaissance battle is very important, as it limits the information the enemy is able to collect and use in planning his attack.

The OPFOR dedicates extensive effort to employing cover, concealment, and camouflage to protect its defensive positions and high-value assets. All units are responsible for providing protective measures for themselves, with support from engineer units. The OPFOR employs a variety of signature-reducing or -altering materials and systems, including infrared- and radar- absorbing camouflage nets and paints.

In the defense, the OPFOR emphasizes radio silence and alternate communications methods such as landline and couriers. Rigid adherence to information security procedures and limiting radio transmissions to the minimum required can complicate the enemy's attempts to identify defensive positions and force structure.


Each level of command prepares a deception plan prior to every defensive operation. The extent and complexity of this plan depend on the amount of time available for preparation. Obviously, a defense out of contact allows the most effective and complete planning for a deception operation. In any case, the OPFOR realizes that uncoordinated efforts without a centralized plan can lead to reduced or even negative results. Therefore, it undertakes deception activities in a deliberate manner. Particularly, coordination among staff elements, between levels of command, and with adjacent units must be constant and detailed, in order to avoid misleading friendly forces or bringing attention to an actual planned operation.

Deception planners create a "story" or picture of the battlefield the OPFOR wants the enemy to see as reality. The goal is to cause the enemy to commit his forces in a manner that favors the OPFOR's defensive plan. Specifically, the intent is to have the enemy attack and penetrate the defense at a location of the OPFOR's choosing, where it has created a lethal antitank defense and counterstrike to destroy the enemy main force.

The OPFOR deception planners understand that, in order to deceive the enemy, they must provide the signatures his intelligence collectors and planners are looking for as indicators of OPFOR activity or assets. The more types of signatures presented, the greater the potential effect of the deception. Examples of deception measures and activities include--

  • Concealing troop movements and secretly occupying defensive positions.
  • Creating indicators of false units and movement.
  • Establishing dummy artillery positions, SSM deployments, or CPs.
  • Creating false defensive positions and engineer obstacles.
  • Establishing false airfields and early warning sites.
  • Establishing a security zone and forward positions to conceal actual forward edge of the defense.

When planning a specific deception effort, the OPFOR attempts to replicate all associated signatures. As an example, the OPFOR might plan to portray the movement of a second-echelon mechanized or tank force that does not exist, while masking the actual unit's movement. This requires a number of activities.

To provide a picture for ground or airborne radar reconnaissance, the OPFOR can deploy deception jammers and corner reflectors along the false route of advance. Smoke pots and generators along with heat sources provide the thermal signatures expected. A special signal element provides false radio traffic replicating the communications associated with a mechanized or tank unit in movement. If enemy ground reconnaissance forces are near, it is even possible to use loudspeakers to provide the sounds of tracked and wheeled vehicles.


The goals of an army defensive operation include some or all of the following:

  • Repel an attack or counterattack by superior forces.
  • Inflict maximum losses on the enemy.
  • Support the development of an attack on an important direction.
  • Hold vital operational lines or areas.
  • Cover the flank of the army group main defense.
  • Restore the combat capabilities of the army when it has taken such heavy casualties that it cannot continue to attack.
  • Create favorable conditions for the initiation of an attack, either by the army or by other forces.

To achieve these goals, the army's missions are to--

  • Destroy enemy precision weapons.
  • Inflict heavy loses on the enemy's main grouping as it approaches and deploys to attack.
  • Repel the enemy attack and hold vital ground.
  • Destroy any enemy groupings penetrating through the depth of the defense.
  • On sea coasts, repel any amphibious landings.
  • Create conditions for a transition to the offensive.

Reasons for Assuming the Defense

Army-level defensive operations are generally a forced, temporary form of combat employed in support of and in the interests of offensive actions. The purpose often is to inflict losses on the enemy's strongest groupings, thereby supporting the conduct of the offense on a critical axis of the army group or theater. Army defensive operations are likely to be more frequent than those of a whole army group. An army may act on the defense in the circumstances described in the following paragraphs.

Army Group Defensive Operation

An army might assume the defensive within the context of an army group defense (whether at the beginning of a war or during the course of operations). In this context, it might defend in the first echelon, either on a main or secondary axis, or it may act in the second echelon, where its primary role would be to launch counterstrikes.

Army Group Offensive Operation

There are several circumstances in which an army might act on the defensive while most or all of the rest of the army group continues to advance. They are--

  • When encountering a superior enemy force on the army's axis.
  • When repelling an enemy counterattack.
  • When defending a bridgehead.
  • When repelling enemy attempts to break out of an encirclement.
  • When defending an extended frontage as an economy-of-force measure to free forces to concentrate on an offensive axis.

Forced Defensive Action

The following conditions might force an army onto the defense:

  • Sustaining heavy losses from precision weapons or massive air attacks.
  • Having the enemy deploy his forces before the army does.
  • Suffering defeat in a meeting engagement.
  • Encountering an enemy with superior forces.

Transition to Defense

Making the transition to the defensive during the course of an offensive often occurs during adverse ground and/or air situations. This transition might even occur under enemy attack. The army's main forces might have already engaged the enemy in combat, with divisions fighting at varying depths and on different axes. All elements of the army might not simultaneously transition to defense. Some might continue to attack to seize favorable lines from which to defend; others might have to deal with enemy air landings in the rear. Often, an army has to conduct its defensive battle with little or no help from the army group. The army group might have concentrated its efforts on continuing the offensive on another axis or on supporting the defense on a more dangerous axis. For OPFOR, transition to the defense occurs either in direct contact with the enemy or out of direct contact with the enemy.

In Direct Contact

After the initiation of hostilities, the OPFOR considers that a defense in direct contact with the enemy is the more likely form of defense. This also occurs during an offensive when an army must assume a defensive mission. An entire army would probably not shift to the defense in direct contact with the enemy. If its forward tactical units transition to the defense, their initial priority is to establish good defensive positions. This might require offensive actions to seize suitable terrain.

Depending on the enemy situation, the commander has limited time to plan. Follow-on forces are more likely to have sufficient time for planning; they can then establish typical defensive positions. Units in direct contact with the enemy while transitioning to the defense are unlikely to withdraw to establish a security zone. Forces would continue to upgrade their positions as long as they are defending. As a result, with the exception of the security zone, the defense in direct contact with the enemy eventually differs little from the defense executed out of direct contact with the enemy.

Out of Direct Contact

A defense established out of direct contact with the enemy can occur before a war begins or along a secondary axis. It can also occur during an offensive, when follow-on army group and army forces must block an enemy's counterattack. If under no direct enemy pressure, the army normally establishes a security zone. The time available for preparing the defense depends on the enemy situation. Of course, an army assuming the defensive before the enemy's attack and on ground of its own choosing is in a much better position to create a stable, enduring defense.

Operational Formation and Tasks

The operational formation of the army in the defense might be in one or two echelons with a combined arms reserve. However, the organization for combat and positioning of forces are not fixed. They differ in each instance according to--

  • The operation and the army's missions.
  • The forces available to the army commander.
  • The composition of enemy groupings and the character of their actions.
  • The terrain.

OPFOR commanders are expected to maximize use of the terrain and to avoid establishing patterns that could aid enemy planning and targeting. Normally, the operational formation is deep to allow unhampered maneuver (especially of second echelons and reserves), to reinforce the resistance against the main threat, and to achieve dispersion against precision-weapon attack.

Figures 6-2 and 6-3 are examples of how an army might deploy in the defense, representing two extremes. The first example is for a small army defending on a narrow frontage with relatively shallow depth. The second example is for a very large army defending a wider frontage and deployed in maximum depth. Actual deployment of a given army could be anywhere between these two extremes, and other variants are possible, depending on the situation. The following paragraphs present the options for operational formation and defensive layout of an army in the defense.

Figure 6-2. Example army operational formation in the defense (variant 1).

Figure 6-3. Example army operational formation in the defense (variant 2).


An army with two divisions in its first echelon might defend a sector as narrow as 40 to 60 km wide. One with three divisions in its first echelon could defend a sector up to 100 km wide; by taking advantage of terrain and economy-of-force measures in some areas, the frontage could reach up to 100 to 150 km. Much depends on the relative strengths of the sides and on the terrain in the sector. An example is that in mountainous, desert, or arctic regions an army might hold a wider sector. An army on a greatly threatened key axis in normal terrain might defend a narrower sector. An army defense deployed in two defensive lines (zones) could have a depth of 50 to 60 km, and one with three defensive lines (zones) could have a depth of 80 to 100 km or more on an important axis.

Forward Edge of Defense

The selection of the forward edge of the defense often depends on the conditions in which the army goes onto the defensive. First-echelon forces doing so in the course of an attack usually establish the forward edge of the defense on the lines they have reached. Sometimes the selection occurs only after seizure of more favorable terrain further on. Sometimes, it is desirable to establish the first defensive zone on a favorable line within the depth of friendly territory with forward units providing cover for its preparation.

The army commander designates the forward edge; division and brigade commanders confirm it on the ground. Individual division commanders specify the number of defensive positions created and their precise location within the defensive zone of each division.

Security Zone

When organizing a defense out of contact with the enemy, the army commander can establish a security zone in front of the main defensive zone.3 This security zone can be up to 15 to 50 km deep. Forces in the security zone may be an army-level, brigade-size forward detachment taken from a second-echelon division and/or smaller forward detachments consisting of reinforced battalions drawn from the second-echelon brigades of first-echelon divisions. A brigade defending in the security zone usually deploys in one echelon of three reinforced battalions. These forces conduct a maneuver defense, withdrawing from one prepared position to another when pressure grows too strong.

A security zone serves several purposes, such as to--

  • Detect the enemy's main groupings and intentions.
  • Delay the enemy, allowing the preparation of defense and counterstrikes.
  • Deceive the enemy as to the location and configuration of the main defensive zone.4
  • Force the enemy into premature deployment.
  • Canalize the enemy onto unfavorable axes.

Strong combat support elements, especially artillery, provide support to the security zone battle. On the most important avenues, 3 to 5 km forward of the forward edge, battalions detached from first-echelon brigades might establish forward positions.

First (Main) Defensive Zone

First-echelon divisions establish the first defensive zone, which is usually the main defensive zone. Within the main defensive zone, each division can hold three or more positions, with each brigade holding two defensive positions and each battalion, one. The basis of each position is company strongpoints integrated into battalion defensive areas. Each battalion position is 3 to 5 km wide and about 2 km deep, with gaps of up to 5 km between battalions. Generally, a brigade has a frontage and depth of up to 10 km. A division has a sector up to 30 km wide (as little as 20 km on a key axis) and 20 to 25 km deep.

The tasks of the first-echelon divisions are to repel enemy attacks, inflict maximum casualties on attacking enemy force groupings, and prevent penetration. Should that be impossible, the tasks become holding vital ground and supporting second-echelon (reserve) counterstrikes.

Second and Third Defensive Zones

Behind the main defensive zone, an army establishes at least one more defensive zone, and possibly two. A distance of about 15 km typically separates the rear edge of one zone from the forward edge of the next. The location of these zones depends on the terrain, the likely character of enemy actions, and the army's concept of operations. The army's second echelon and/or combined arms reserve occupy these zones. Sometimes, the army has engineers prepare a third defensive zone but does not occupy it initially.

The army's first and second defensive zones constitute the tactical zone of defense. A third army zone, if present, is part of the operational zone of defense. The army's second and third zones each can consist of one or two defensive positions. Thus either of these zones is typically 15 to 20 km in depth.

An army may have either a second echelon or a combined arms reserve, or both. The army's decision on forming these groupings and the strength of either force depends on the--

  • Army's strength.
  • Width of the army's sector.
  • Army's mission.
  • Importance of the axis.
  • Conditions under which the defense occurred.
  • Strength of the enemy.

In the defense, the roles of the second echelon and combined arms reserve are not as clearly distinguished from one another as in the offense. Either of these forces may perform essentially the same roles; it is just a matter of which roles are the primary or most likely tasks for each type of force. Basically, the role of any force other than the first echelon seems to depend on what the enemy does (the strength of the enemy force and how far it can penetrate into the OPFOR defense).

The army generally forms a combined arms reserve in the second defensive zone when there is no second echelon. The primary roles (contingencies) for such a reserve are to reinforce or relieve first-echelon forces or to hold defensive lines on vital axes, or to remain ready to deal with unexpected situations and conduct new missions that arise in the course of the defensive operation. However, it may also perform antilanding missions (especially if there is no dedicated antilanding reserve). Especially when there is no second echelon, the combined arms reserve is responsible for counterattack or counterstrike missions. Even when there is a second echelon, the combined arms reserve might have to support the second echelon in the counterstrike if the penetrating enemy force is strong enough. If the enemy attack is too strong to be defeated at army level, the army combined arms reserve (possibly along with the army second echelon) may support an army group counterstrike.

The initial deployment area of the army's second echelon is likely to be in the second defensive zone. Its primary mission is to launch a counterstrike and to restore the stability of the tactical zone of defense. However, the situation may require it to perform roles normally associated with the combined arms reserve. For example, the army may have its second echelon reinforce the efforts of the first echelon on the main axis, possibly relieving first-echelon troops that have lost combat effectiveness. The second echelon might have to hold firmly in the second defensive zone to halt enemy penetration. If the army has no combined arms reserve or dedicated antilanding reserve, it may also call on the second echelon to destroy enemy air landings.

If a collapse of the first echelon has allowed complete penetration of the tactical zone of defense, the role of the second echelon may be to establish a last line of counterpenetration defense on the enemy's main attack axis. In some cases, elements of the second echelon may have deployed initially in a third defensive zone, with this mission as an option to a counterstrike. Otherwise, elements may have to redeploy to prepared lines in the operational zone of defense for the mission of holding those lines until the army group can mount a decisive counterstrike. Sometimes the second echelon canalizes the enemy forces into an area that allows the army group counterstrike to destroy them.


Besides the combined arms reserve, the army commander often creates a dedicated antilanding reserve. Special reserves in the operational formation can include engineer, chemical defense, reconnaissance, communications, and medical reserves. There is always an antitank (AT) reserve based on the army's AT regiment but often reinforced with other artillery and tank and/or mechanized infantry assets. This almost invariably works in tandem with a mobile obstacle detachment (MOD).

The AT reserve and MOD deploy on or near the most important or most threatened axis ready to move quickly to prereconnoitered counterpenetration positions. These various types of reserves, when established at army level, typically locate in the second defensive zone or in the space between the first and second zones.

Fire Support

An army typically has two SSM brigades. Although both brigades have short-range ballistic missiles, one brigade typically has longer-range missiles than the other. Each SSM brigade has one main and one or two alternate deployment areas.

Brigade positions for the longer-range SSMs are usually 60 to 80 km from the forward edge of the defense and to the flank of the likely direction of attack.5 For shorter-range SSM brigades, positions typically are 15 to 30 km from the forward edge (in the space between the army's first and second defensive zones). However, it is possible that some army-level SSMs could deploy initially to temporary positions much closer to the forward edge or even within the security zone. Final positioning is based on mission, target, and survivability. The brigade's principal tasks are to--

  • Destroy precision weapons.
  • Destroy key target acquisition assets.
  • Conduct NBC strikes on main forces and airfields.
  • Disrupt C2.
  • Destroy air defenses.
  • Disrupt logistics support.

The commander may not form an army artillery group (AAG) if the army must defend in a wide sector or if there is no axis more obviously important or threatened than any other. If formed, the AAG deploys on the most important axis, probably about 10 to 12 km from the forward edge of the defense. The AAG's principal tasks are to--

  • Conduct counterbattery fire.
  • Reinforce the artillery of first-echelon divisions.
  • Disrupt the approach and deployment of strike groupings (including, if possible, counterpreparatory fires).
  • Support the launching of counterstrikes.
  • Separate enemy tanks and infantry in the assault.
  • Destroy enemy CPs and logistics elements.
  • Destroy enemy airborne or amphibious landings.

An army normally does not allocate the multiple rocket launchers (MRLs) of its organic MRL brigade to its subordinate divisions. With these and additional MRL battalions possibly allocated to the army from the army group-level MRL brigade, the army commander would form an army rocket artillery group (ARAG). An army may have from three to seven MRL battalions for this purpose. With closer to seven battalions, the army might form two ARAGs.

An ARAG is normally reserved for centralized employment on the army's most important axis, probably about 10 to 12 km from the forward edge of the defensive area. The ARAG does not include SSM units.

System of Fire

The OPFOR pays particular attention to its AT defense throughout the defended area, especially on the best tank approaches. A maneuver division's AT defense should be capable of repulsing the attack of two enemy divisions. The army commander might reinforce defending divisions with troops from a less-threatened axis or from army AT reserves or MOD. Antitank weapons deploy within the defended positions of battalion defensive areas (within company strongpoints) on tank-threatened axes. Firing lines for AT reserves are predesignated and, if possible, prepared.

Commanders integrate the system of fire with the system of natural and artificial obstacles. The army's system of fire also includes the following types of artillery fires:

  • Long-range fires. Artillery fires on obstacles, crossings, defiles, road junctions, and likely routes approaching the forward edge.
  • Fire to the immediate front. Artillery delivers massive fire concentrations and barrages, both moving and standing, on several lines in front of the forward edge (approaching no closer than 400 m from friendly positions). Assembly areas and approaches are primary targets.
  • Fire in the depth of the defense. In depth, the artillery delivers fire concentrations and barrages to likely areas of penetration, the axis of planned counterstrikes, and the flanks.

The principal organizers of the fire system are division commanders, using their chiefs of artillery. However, the army commander is responsible for--

  • Coordinating between divisions.
  • Conducting the maneuver of fire to threatened areas and to cover boundaries and flanks.
  • Organizing counterpreparatory fires.
  • Organizing preparatory and supporting fires for counterstrikes.
  • Calling on fire from second-echelon or flanking divisions.

Engineer Support

Engineer works are vital to the stability of the defense. Of course, such work is not just an engineer responsibility, it is a combined arms task.

Divisions occupying defensive zones concentrate on--

  • Digging weapons pits and trenches.
  • Constructing observation posts, CPs, and medical centers.
  • Creating obstacles in the security zone, in gaps in the combat formation, and to the flanks.
  • Preparing fields of fire for AT weapons.
  • Preparing lines for counterpenetration and counterattack/counterstrike and routes to such lines.
  • Preparing bridges and other vital targets for demolition.
  • Establishing water supply points.

In conjunction with other tasks, engineers support the deception plan through activities such as constructing false defensive positions and preparing false routes.

After engineers complete initial tasks, their second priority is to--

  • Integrate weapons pits into squad/section and platoon trenches and prepare alternate positions for tanks and other weapons.
  • Improve lines of commitment for counterattacks/counterstrikes and routes to them.
  • Increase the density of obstacles in front of the forward edge, in depth, to the flanks, and in gaps.

At army level, engineer units specializing in rapid obstacle construction and minelaying form MODs. These MODs normally deploy in conjunction with AT reserves to block enemy penetrations or to protect the flanks of counterstrike forces. Other engineer units may form an engineer reserve at the disposal of the army commander for situations that require additional engineer support.


With the initiative in the hands of the attacker, timely intelligence is vital to forestalling the enemy with counterpreparatory fires and to prepare timely counterstrikes. The organization of reconnaissance includes--

  • Planning and issuing missions to troops executing reconnaissance tasks.
  • Establishing a reconnaissance reserve.
  • Coordinating reconnaissance efforts with combat and combat support.
  • Organizing communications, including groups operating in the enemy rear.

Collecting, assessing, and analyzing information and disseminating intelligence to higher, lower, and flanking headquarters.

Types of Defensive Action

There are several types of defensive action an army can employ depending on the combat circumstances. The following paragraphs detail these actions, which parallel those conducted at the army group level.

Counterpreparatory Fires

The goal of counterpreparatory fires is to inflict heavy losses and delay enemy forces preparing to attack the forward edge. This is usually an action planned at army group level and executed at the army level. Under some circumstances, an army may conduct counterpreparatory fires within its own area in accordance with instructions from the army group commander. Fire support assets involved can include army-level artillery and SSMs, army aviation helicopters, and some support from army group aviation. When it involves artillery from more than one army, army group SSMs, and the main forces of army group aviation, the army group commander organizes it. To conduct counterpreparatory fires, a division needs 3 to 5 hours planning time. Planning at army level might require 6 to 8 hours.

A successful counterpreparation needs much artillery--30 to 40 guns, MRLs, and mortars per km of frontage. To produce the right density, the army can involve not only the artillery of the threatened divisions and the AAG but also the weapons of adjacent divisions and sometimes of second-echelon divisions as well. Precision weapons, if available, can reduce the requirements for massed artillery in counterpreparatory fires.

To be successful, counterpreparatory fires must also take the enemy by surprise (preferably as the enemy is completing his attack preparations) and be based on accurate reconnaissance data. The counterpreparatory fires usually last 25 to 40 minutes. Fires reach 10 to 30 km over the forward edge (25 to 30 km if supported by army group aviation as well). The OPFOR fire strikes combine fires with EC directed against enemy artillery and air support nets, target acquisition assets, and C2 elements.

Spoiling Attacks

Spoiling attacks may follow the counterpreparatory fires to inflict further casualties, disruption, and delay on enemy forces as they prepare to attack. Usually, the army uses brigade- or battalion-size elements of its second echelon or combined arms reserve in this role to avoid compromising the stability of the defense. A spoiling attack can strike targets of opportunity created by counterpreparatory fires, such as destroying a weakened and isolated enemy unit before it can be reinforced. When the army group does not organize counterpreparatory fires in a particular army's sector, that army may use spoiling attacks to disrupt or delay the enemy attack.

Security Zone Battle

The forces allocated to the security zone conduct a maneuver defense from a series of positions on main approaches. They receive support from allocated artillery units engaging the enemy from temporary firing positions. Division and brigade artillery groups from the main defensive zone may supplement the fires of artillery in the security zone. The artillery groups fire with guns and MRLs generally start to engage targets 15 to 25 km from the forward edge of the main defensive zone. Howitzers typically begin to fire when the enemy is within 10 to 15 km. Also possibly located in the security zone are deep fire systems such as army-level SSMs and MRLs to hit the enemy on distant, as well as, near approaches. During the fight in the security zone, the OPFOR determines the axis of the enemy's main attack. First-echelon divisions improve their defenses by reconfiguring their plans and regrouping as necessary onto critical axes.

Repelling Enemy Attack

During the actual start of the enemy attack, all available weapons open intensive fire to disrupt attacking groupings, to separate tanks from infantry, and to neutralize fire support. They create favorable conditions for the destruction of mechanized forces by AT systems. This occurs regardless of whether or not the army had time to establish a security zone. Once the OPFOR identifies the enemy's axes of attack, it reinforces its defenses on those axes. Reinforcing the axes increases the density of AT weapons and obstacles, and adds depth to the defense. The army commander then adjusts and confirms the missions of aviation, artillery, mobile AT reserves, and other troops.

Where the enemy achieves penetration into the main defensive zone, the OPFOR must firmly hold advantageous positions and take measures to prevent enemy advances into the depth or against the flanks of stable defensive groupings. Brigades and divisions mount counterattacks to destroy minor penetrations and to restore the main positions. If faced with a major penetration, however, the second echelons of divisions receive orders to hold deep defensive positions and delay the enemy.

Counterstrike and Counterpenetration

The battle for the tactical zone of defense normally requires not only brigade and division counterattacks but also a counterstrike by the army's second echelon or combined arms reserve. Where the enemy penetrates the main defensive zone on several axes in superior strength, the army's response may be limited to counterpenetration. This is to restore the stability of the defense and to create favorable conditions for launching army group-level counterstrikes. Figure 6-4 illustrates an example of army-level counterpenetration and counterstrike, as well as tactical-level counterattacks.

Figure 6-4. Army-level counterpenetration and counterstrike (example).

The army counterstrike against forces penetrating into the depth of the defense is usually the decisive move of the defense, thus regaining the initiative from the attacker. Ideally, the destruction of the penetration creates favorable conditions for going over to the offensive. However, the army might mount the counterstrike when conditions are less favorable. If so, the army might have more limited aims, such as the destruction of the most threatening grouping penetrating the defense or the restoration of the defense on a favorable line.

Another means of regaining the initiative is for the OPFOR to concentrate overwhelming force against an enemy supporting effort, while maintaining the defense against the enemy's main effort. Because enemy commanders sometimes reinforce failure, a counterstrike against an enemy supporting effort may cause the enemy to abandon a successful main effort in favor of saving the supporting effort. This type of counterstrike accepts a greater degree of risk to the defense than a counterstrike against the enemy's major penetration. Nevertheless, a counterstrike against a supporting effort does have the potential to achieve decisive results with smaller forces.

Other uses of counterstrikes are to eliminate the threat of encirclement, to divert enemy forces from his main axis, and to force the enemy to regroup. The timing and axis of the counterstrike are crucial, although of the two, timing is perhaps the most important.

Timing. The army commander should launch his counterstrike before the enemy compromises the firmness and sustainability of the first echelon's defense. He may also launch his counterstrike when the enemy has taken heavy losses and slowed down or even stopped but before he has consolidated his gains. Especially favorable times for counterstrikes occur--

  • When the enemy is relocating his artillery.
  • When the enemy has exhausted his immediate reserves.
  • While deeper reserves are still too far away or delayed by air attack.

Critical to the army commander is the timing of his counterstrike. He must consider the army's mission, movement routes and lines of commitment for the counterstrike force, obstacles, and the possibility of enemy interdiction. He must also take into account the time the second echelon or reserve requires to move from positions in the army's second or third defensive zone and to deploy at the designated line of commitment for the counterstrike. This includes the time to issue and react to orders.

Axis. The aim, terrain, and the time it takes to achieve a concentration on one axis rather than another determines the direction of the counterstrike. Normally, the OPFOR mounts the strike against one or both flanks of the enemy penetration. This is the most efficient way to cut off spearheads from enemy reinforcements, attack enemy precision weapons and CPs, and split up and destroy enemy forces piecemeal. However, the OPFOR does not exclude direct attacks to split the enemy. The use of the direct attack can be dictated by--

  • The terrain.
  • The lack of time to move forces to a flank.
  • The opportunity to achieve surprise.
  • The need to re-establish the defense on a specific favorable line.

Whatever axis the commander chooses, he must determine and prepare in advance the routes to the line of departure and to the line of commitment. He must ensure that defensive lines of forces covering the flanks of the movement route remain firmly held. He can plan in advance for possible counterstrikes in two or three sectors. In each sector, he designates a line of commitment, or possibly two lines about 10 km apart.

The OPFOR must have the necessary COF superiority over the enemy. To this end, the forces of the first echelon on the axis of the counterstrike can reinforce the army second echelon (reserve). After regrouping, other first-echelon elements drawn from sectors not under heavy pressure can reinforce the second echelon in the counterstrike. Powerful fire strikes must precede the counterstrike. Therefore, the bulk of the army-level artillery combines with that of the second echelon and as much of the first echelon's as can be brought to bear. This is also the time for the maximum commitment of air support, with the especially important task of isolating the penetrating enemy force and delaying the forward movement of reserves.


The General Staff (or CINC of the theater) specifies the goals of an army group defensive operation, depending on--

  • The strategic mission (and/or theater commander's concept of operations).
  • The significance of the axis to be defended.
  • The missions of adjacent army groups.
  • The likelihood of enemy air and ground attacks and their likely strengths.

In most cases, the goal is to repel enemy attacks, inflict maximum casualties, and retain important lines or zones. The goal might also be to establish favorable conditions for subsequent offensive operations. At the start of a war, this includes covering the deployment of strategic groupings and their organized commitment into combat.

Therefore, missions might include--

  • Inflicting heavy casualties on the enemy's approach to the defended area.
  • Repelling ground and air attacks.
  • Destroying penetrations of defended areas.
  • Eliminating enemy airborne, heliborne, or amphibious landings.

For each of these missions, part of the responsibility actually falls within the armies (or corps) subordinate to the army group. However, each mission also has a part left to the army group level, and the army group commander has overall responsibility.

Transition to Defense

The circumstances under which the OPFOR transitions to a defensive operation determine the structure and strength of the defense. The primary determining factor is whether or not the army group is in contact with the enemy at the time.

In Direct Contact

After the outbreak of war, the OPFOR is more likely to adopt a defense in contact with the enemy. If a force is under strong counterattack or has been defeated in a meeting engagement, the commander has limited time to prepare his defense.

Preparation must occur simultaneously with efforts to repulse enemy ground and air attacks and to stabilize the first echelon's position on favorable ground. The weight of the defense is likely to be forward, quite possibly on the wrong axes. Even as the defense is being established, the OPFOR may have to conduct limited offensive action in order to seize favorable ground.

Out of Direct Contact

There are several conditions that can cause an army group to establish a defense out of contact with the enemy. One is when the army group is preparing to defend before the outbreak of war. Another is when it is preparing deep defenses during the course of hostilities.

The defense out of contact with the enemy generally has a relatively long preparation period. The OPFOR prepares alternative plans for enemy attacks on different axes and begins extensive engineering work. Complete preparation of an army group's defensive zones may to require 8 to 10 days. Deception efforts prepared during a defense out of contact also benefit from additional planning time. Combat units do not deploy until the last minute to maintain secrecy and to give maximum time to study the enemy deployment. In a defense out of contact, the bulk of the army group's combat power may be in the rear to allow freedom and time to maneuver.

Operational Formation and Tasks

The operational formation of an army group in the defense might be in one or two echelons with a combined arms reserve. Even more so than at army level, the organization for combat and positioning of forces are not fixed. They differ in each instance according to--

  • The operation and the army group's missions.
  • The forces available to the army group commander.
  • The composition of enemy groupings and the character of their actions.
  • The terrain.

OPFOR commanders must maximize use of the terrain and avoid stereotyped patterns. A deep operational formation allows unhampered maneuver of second echelons and reserves to meet the main threat. It also provides dispersion against precision weapon attack.

Figures 6-5 and 6-6 are examples of how an army group might deploy in the defense, representing two extremes. The first example is for a small army group defending with relatively shallow depth. The army group in this first variant has a clear idea of where the enemy's main attack is about to occur and has organized an operational fire sack to defeat a penetration in that sector.

Figure 6-5. Example army group operational formation in the defense (variant 1).

Figure 6-6. Example army group operational formation in the defense (variant 2).

The second example is for a very large army group deployed in maximum depth. This variant shows a situation where the OPFOR has had time to prepare a defense in great depth but does not yet know where the enemy's main attack will be.

Actual deployment of a given army group could be anywhere between these two extremes, and other variants are possible, depending on the situation. The following paragraphs present the options for operational formation and defensive layout of an army group in the defense.


The scope of the defense depends on the army group's composition as specified by the General Staff (or theater CINC). An army group has no fixed organization. Structure depends on the composition and strength of the expected enemy attack and on the terrain and nature of the theater.

The ground maneuver forces of an army group may comprise one to four armies and possibly one or two separate divisions and/or a separate brigade. An army group may have one or two corps (in lieu of armies). In addition to these ground maneuver forces, an army group normally has an air army. It can also have a special-purpose forces (SPF) brigade, a naval infantry brigade, and possibly an airborne infantry brigade allocated to it. Most of the army group's combat support elements are not organic assets; the General Staff allocates them to the army group from a national pool of assets known as the Reserve of the Supreme High Command.

An army group might defend on a frontage of as much as 350 to 400 km, to a depth of 250 to 300 km. In some cases, the area of responsibility may be larger. In other cases, it could be considerably smaller, in frontage or in depth. A determining factor is the need to achieve adequate force density to repel the enemy. Ideally, the force density should provide a first-echelon division per 20 km of frontage on a main axis and per 30 or more km on a secondary axis. However, such a density may not always be possible (or necessary). The OPFOR may have to accept lesser densities in sectors where no attack is expected. The army group and its subordinate armies or corps would also have to maintain second echelons and reserves appropriate for the weight of the expected attack.

Tactical Zone of Defense

The army group's first echelon repels attacks, holds important areas, and creates favorable conditions for counterstrikes. Usually, but not invariably, the bulk of the army group is in the first echelon. First-echelon armies deploy in the first two or three defensive zones. The first two army zones comprise the tactical zone of defense. When organizing a defensive operation out of contact with the enemy, the army group commander or one of his army commanders can establish a security zone in front of the army's first (main) defensive zone. (See the "Army Defense" section of this chapter for more detail.)

Operational Zone of Defense

A first-echelon army can hold its combined arms reserve and/or part of its second echelon in an army third defensive zone, to the rear of the tactical zone of defense. From this third zone, the army can mount counterstrikes against penetrations of the tactical zone of defense. Alternatively, the army may employ counterpenetrations against very strong and successful penetrations. With this third zone, the total depth of a first-echelon army could be 85 to 100 km.

Behind the army's last (second or third) defensive zone, the remainder of army group deploys in one or two additional defensive zones. Together with the army's possible third defensive zone, the army group zone(s) constitute the operational zone of defense. The army group's combined arms reserve and/or second echelon deploy there. If time permits, the OPFOR prepares defenses in the operational zone to serve as alternate positions for occupation by forces withdrawing from the tactical zone.

The army group's combined arms reserve consists of one or several maneuver divisions. It normally deploys in the army group's first defensive zone. Its primary role is the reinforcement of forces operating on decisive axes, the relief of battered divisions, the destruction of airborne landing forces, or the execution of other, unexpected missions that may arise in the course of defensive operations.

In the absence of a second echelon, the army group establishes a strong reserve that also has the responsibility for conducting a counterstrike. Even when there is a second echelon, the combined arms reserve can join in the counterstrike.

The army group normally plans for counterstrikes on two or three axes. A distance of 80 to 100 km typically separates the forward edge of the zone occupied by the counterstrike force from the forward edge of the defensive zone in front of it. This distance allows dispersed concealment and deployment of the second echelon or combined arms reserve and gives it the capability to conduct quick maneuver on a choice of axes to launch counterstrikes or accomplish other missions.

If the army group establishes two defensive zones, a second-echelon army (or corps) usually deploys in the second zone, behind the combined arms reserve. If there is only one army group zone, the second echelon deploys there, possibly along with a smaller combined arms reserve. In either case, its primary role is to act as a counterstrike force to destroy major penetrations and, usually, to restore stability to the tactical zone of defense. In the event of a collapse of the first echelon, however, all or part of the second echelon might establish a defense on vital lines in the operational depth on the enemy's main axis.

The total depth of this defense, with three army zones and two army group zones, may reach up to 250 to 300 km from the forward edge.


The army group commander establishes his AT reserve(s) from organic or allocated AT brigades. They almost always work closely with the engineer MODs, of which the army group usually establishes two. Together, these AT forces--

  • Reinforce the AT defense of the first echelon.
  • Act as counterpenetration groupings.
  • Deploy to support the commitment of army group counterstrikes.

The army group can establish the same types of special reserves as found at army level. It is also likely to have a specialized antilanding reserve. Likely sources for the latter role are separate mechanized infantry or tank brigades or possibly an airborne infantry brigade; the antilanding reserve could be an entire brigade or one or more reinforced battalions.

Command Posts

An army group may deploy up to six types of CPs (excluding dummies) as follows:

  • The main CP normally deploys close behind the rearmost army defensive line, to the flank of the most likely axis of the main attack.
  • The alternate CP deploys to the flank or rear of the main CP and is constantly manned by an operations group from army group headquarters; it also has redundant communications.
  • The forward CP usually deploys in the tactical zone of defense; it can control army group-level counterstrikes.
  • The rear CP deploys with the army group forward base in the rearmost army group defensive zone, and is able to take over from the main CP if required to do so.
  • The army group commander uses an airborne CP when he visits an area of operations.

The commander might establish an auxiliary CP to ease C2 problems of formations operating on an independent axis.

Fire Support

The army group allocates its tube artillery and MRL assets to subordinate armies or corps. However, it normally retains control of its organic SSM brigades and army group aviation.

The army group commander assigns his SSM brigade(s) a primary area generally 60 to 80 km from the forward edge, with one or two alternate areas 15 to 30 km apart for each brigade. This places the army group-level SSMs at roughly the same depth as the army's longest-range SSMs. However, each army group brigade can also have an alternate position farther to the rear, behind the tactical zone of defense. These distances may be modified based on the brigade's mission.

For army group aviation, airfields for fighter-bomber and reconnaissance aircraft are generally 100 to 150 km from the forward edge, with bomber bases 200 to 300 km distant. Each aviation division has an airfield complex that includes four to six operational airfields and two or three reserve fields.

System of Fire

The basis of the defense is a coordinated and integrated system of fire that is primarily antitank (AT) in nature. Antitank weapons are deployed to achieve interlocking fires along the forward edge and in depth. The AT reserves, up to army group level, provide a quick-reaction AT force to block penetrations, generally along with MODs. Commanders carefully integrate obstacle and barrier plans with fire plans to create fire sacks.

The system of fire includes--

  • The organization of fire strikes.
  • The establishment of multilayered, massive fires of all types of weapons.
  • Preparation for the maneuver of fire onto all axes.

Generally, aircraft engage targets beyond artillery range as well as moving and point targets.

The OPFOR's system of fire and air strikes can--

  • Destroy enemy precision weapons.
  • Inflict losses on enemy maneuver forces in their assembly areas, during their forward movement, while they are deploying, and in attack positions.
  • Repel or destroy massed tank/infantry attacks, if they penetrate the defense.
  • Neutralize artillery, air defenses, CPs, and radars at appropriate stages of the operation.
  • Provide strong fire support to friendly troops operating in the security zone.
  • Forestall the enemy attack with surprise counterpreparatory fires where intelligence makes it possible.
  • Bring to bear the full weight of available fire support to support counterstrikes.
  • Cover flanks, intervals in operational formations (otherwise covered only by obstacles), and gaps created by enemy nuclear or precision weapon strikes.

Types of Defensive Action

An army group can employ several types of defensive action depending on the combat circumstances. The following paragraphs detail these actions, which parallel those conducted at the army level.

Defense Before Enemy Penetration of Forward Edge

Much depends on whether the OPFOR assumes the defense in or out of contact with the enemy. If out of contact, the army group initiates the engagement by hitting the enemy on distant approaches, with air and missile strikes and, especially, precision weapons. Principal targets are enemy precision weapons, main force groupings, airfields, air defense forces, CPs, and key logistics elements.

Before the enemy launches the attack, the OPFOR executes surprise counterpreparatory fires by air, missile, and artillery strikes. Even if the enemy attack is focused on one army, artillery in adjacent areas can participate as long as it is within range of the attacking force. When counterpreparatory fire involves the artillery of more than one army, army group SSMs, and the main forces of army group aviation, the army group commander organizes it. An army group fires its counterpreparation over a period of 25 to 30 minutes, normally on a sector 20 to 25 km wide at the junction of two armies, and to a depth of 25 to 30 km. The required artillery density can be approximately 40 to 50 weapons per km of frontage. The use of precision weapons, if available, would reduce the duration and density of the counterpreparation.

If the army group transitions to the defense in contact, the defense is much more difficult to establish because operations might begin before completing preparations and reorganization. If so, elements of the army group might have to continue the attack in order to seize an advantageous line.

Defense After Enemy Penetration of Main Defensive Zone

As the penetration of the tactical zone of defense develops, army mobile AT reserves move to the threatened axes. Other forces redeploy from secondary sectors. Any bypassed or encircled forces hold their positions firmly and absorb as much of the enemy's forces and attention as possible. These units should receive as much air and artillery support as possible (including aerial resupply). Encircled forces receive permission to break out and withdraw only when their actions in the encircled position cease to tie down substantial forces. While the battle for the tactical zone of defense continues, army and army group engineers prepare new defense lines and develop the obstacle system to add further depth to the defense on the threatened axes.

Operational-Level Counterstrikes

The counterstrike is the key to a successful defense. No matter how well prepared, forces engaged in a passive defense are more likely to be defeated.

At any level, the immediate mission of the counterstrike is the destruction of the enemy, usually achieved by hitting the flanks or rear of the main enemy grouping. In the most favorable circumstances, the immediate mission might be to encircle and destroy the main enemy force grouping. The most favorable circumstances are when the enemy has committed all his reserves, has taken heavy losses, and has had his C2 disrupted, while the OPFOR has gained or held air superiority.

Subsequent missions include the complete elimination of the penetration, the restoration of the integrity of the defense, and the defeat of enemy reserves advancing to the area. The subsequent mission often involves the seizure of favorable lines from which the OPFOR can launch an army group offensive or strategic counteroffensive. Compared to a counteroffensive, the counterstrike is a more limited blow designed to destroy enemy elements but not necessarily to recover lost ground. It exploits a temporary enemy vulnerability by inflicting a decisive blow against an important enemy grouping.

The OPFOR prefers to conduct counterstrikes against disrupted or halted enemy penetration attempts. It may, however, launch them against an advancing enemy grouping, resulting in a meeting engagement. A short but intense artillery and air preparation usually precedes counterstrikes. Ideally, the OPFOR executes the counterstrike into the flanks or rear of the penetration, exploiting gaps and ruptures in the enemy's operational formation. Mobile AT reserves and MODs protect the flanks of counterstrike groupings. Air interdiction and remote mining prevent counteraction by enemy reserves. After restoring the defense, OPFOR troops regroup. This enables reconstitution of a deep operational formation and reserves. Alternatively, if the enemy exhausts his own reserves, the OPFOR commander might develop the counterstrike into a counteroffensive.

The OPFOR launches army-level counterstrikes either on the instructions of the army group commander or on the basis of the army commander's decision. A maximum effort made by army group assets (especially air) supports them. The army group commander may commit his combined arms or special reserves. If the enemy attack is strong, the army's second echelon might hold prepared lines in depth. If the enemy breaks into the army's second defensive zone with significant forces, the most important tasks become--

  • Stopping the advance.
  • Inflicting maximum losses.
  • Isolating the penetrating force from follow-on groupings.
  • Preventing the movement of enemy reserves.
  • Creating favorable conditions for mounting an army group counterstrike.

The OPFOR launches army group-level counterstrikes to destroy or at least contain the penetrating enemy force on the most decisive axis. The containment of the enemy offensive may also trigger a counteroffensive by one or more army groups. (A weak enemy sector is an ideal target.) The following conditions favor an army group counterstrike:

  • When first-echelon armies maintain their combat capability and firmly hold positions on the flank of the penetration.
  • When the enemy spearhead halts or slows appreciably.
  • When the enemy has taken heavy losses and committed his immediate reserve.

Ideally, the army group counterstrikes against both flanks of the penetration. This gives the best chance of getting into the enemy's rear area and encircling the penetration. However, terrain, or the time involved in moving elements to one flank, might prevent a double encirclement. Time is a critical element, particularly if the possibility of surprise exists.

To launch the army group counterstrike, the commander brings as many forces to bear as possible. These forces might include--

  • The army group second echelon and combined arms and special reserves.
  • All the available resources of army group aviation.
  • Elements of the army group first echelon near the counterstrike. These elements might possibly combine with air landings to block any retreat or the forward movement of enemy reserves.

The counterstrike must use sufficient forces to gather a decisive superiority over the enemy in designated strike sectors.

Defense Against Enemy Airborne and Heliborne Landings

The enemy might try to unbalance the defense and increase his own momentum by using tactical and operational landings. Initially, OPFOR air defense troops and aircraft engage enemy forces conducting these landings. If the enemy forces succeed in landing, the OPFOR must destroy them before they can reorganize to seize and consolidate their objectives. This task belongs to army group aviation and the antilanding reserve.

When an OPFOR commander anticipates an enemy airborne or heliborne landing, he may specifically designate a battalion- or brigade-size force to act as an antilanding reserve. These unit(s) can deploy to likely drop or landing zones, with a mobile force available to maneuver within the area for counterattacks. If a shortage of troops prevents the formation of an antilanding reserve, the commander may use elements of his second echelon or combined arms reserve in this role.


The most decisive engagements, usually inflicting the heaviest casualties, are generally encirclements. Encirclements become more likely in modern warfare, because of the increased mobility of forces and the availability of airborne and heliborne troops to seal the trap.

Several circumstances in which forces may become encircled include the following:

  • As the result of a surprise attack at the outset of a war.
  • When the support for the flanks of offensive or counteroffensive groupings is inadequate.
  • When forces defend areas they cannot abandon.
  • When forces deploy in the enemy rear to defend a city.
  • When trapped against an obstacle.

The OPFOR analyzes the factors the following paragraphs describe, both to reap benefits and minimize consequences.

Costs and Benefits

The enemy sees encirclement as a prelude to the destruction of the trapped grouping. Success in accomplishing its elimination usually creates a significant gap in the defender's order of battle. However, an encircled force can contribute materially to the stability of the defense. Aggressive action by the encircled forces, perhaps reinforced or working with airborne forces, can create a battle front in the enemy rear, severely disrupting his C2 and logistics.

Successful Action and Survival of Encircled Groupings

There are three conditions for surrounded forces to have an impact on the enemy's operations and still survive to break out or be relieved. These preconditions are--

  • There must be firm C2 and adequate logistics support within the encircled force.
  • The main force must be close enough to provide fire, air, EC, and/or intelligence support.
  • The gap between the encircled force and the main forces must not preclude operational coordination.

Problems of Organization Within Encirclement

Perhaps the biggest problem facing a grouping in the process of being enveloped is lack of time to organize to cope with the event. The situation is likely to change rapidly, radically, and unpredictably. Speedy reactions are necessary to maintain combat effectiveness. These include--

  • Immediate measures to centralize the C2 of all elements within the trapped grouping.
  • An immediate assessment of the combat and logistics capabilities of the grouping, quite possibly with measures to strengthen them before the enemy can organize a tight blockade.
  • Redeployment in order to establish a reliable perimeter force and a strong mobile reserve to prevent the enemy from splitting the grouping into fragments, which he could then destroy in detail.
  • Maintenance of stable communications.
  • Creation of a strong air defense umbrella.

In addition, the main force must prevent the enemy from tightly sealing off the encirclement. The main force then increases the interval between the enemy and the encircled force. Air power must be able to make up for deficiencies in the combat support of the encircled force and to ensure its logistics support.


It is unlikely that an encircled force can break out without the aid of the main force. Indeed, the main force usually plays the major role in the operation and thus dictates the plan. Usually, the axes of the encircled and relieving forces must be convergent, on the shortest route separating them. However, the surprise resulting from the choice of other axes may outweigh the obvious advantages of this.

The immediate mission of the breakout grouping is to penetrate the inner arm of the enemy's encirclement. With favorable conditions, the subsequent mission might be to continue the advance against the rear of those enemy forces fighting the main force. Otherwise, the subsequent mission could be to seize and consolidate on an important line (perhaps with the aid of air-delivered troops) until linkup. Screening forces cover both flanks and the rear. Strong combined arms reserves, AT reserves, and MODs may supplement screening forces. Forward detachments are ideal to lead the breakout (and, for deception, on false axes as well). They also serve as raiding detachments to destroy enemy precision weapons and to disrupt C2.


A withdrawal may be necessary in some circumstances, such as when--

  • Establishing a more stable defense on more favorable ground.
  • Shortening the defensive frontage, thus releasing troops for increasing the density of the defense or for offensive missions elsewhere.
  • Avoiding encirclement.
  • Conforming with the retreat of flanking forces.

1 As in the offense, a corps can conduct defensive operations similar to those of an army, but normally on a smaller scale.

2 In OPFOR terminology, a counterattack is a tactical action conducted by divisions. A counterstrike is operational and is delivered by forces of an army group or army. A counteroffensive is usually on a strategic scale; rarely is it operational.

3 The establishment of a security zone is an operational-level decision. A division commander could employ a battalion- or even brigade-size forward detachment in the security zone in front of his own defensive, independent of the operational plan, but must still clear this with the army commander before implementing it. The army (or army group) commander may also decide to employ security zones in front of subsequent defensive zones.

4 Forces in the security zone also can disrupt or destroy enemy reconnaissance assets, thereby limiting information available to the enemy of the OPFOR defense.

5 In cases where the total depth of the army operational formation is as little as 50 to 60 km, the longer-range SSM brigade could be as close as 50 km to the forward edge. This is around the minimum range for such SSMs.

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One Billion Americans: The Case for Thinking Bigger - by Matthew Yglesias