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Chapter 6

DEFENSIVE OPERATIONS

FUNDAMENTALS OF CORPS DEFENSIVE OPERATIONS

Defensive operations are actions the force performs to cause an enemy attack to fail. They help the corps--

  • Gain time.
  • Concentrate forces elsewhere.
  • Wear down forces as a prelude to offensive operations.
  • Retain tactical, operational, or strategic objectives.

The corps generally defends only until it gains sufficient strength to attack. During force-projection operations, forward-presence forces may only defend until sufficient reinforcing forces arrive in theater. Deploying units may also need to conduct defensive operations to support a planned buildup of additional combat power in theater.

A key element of successful defensive operations is to find and destroy the enemy at distance before committing decisive maneuver. The goal is to prevent the enemy from having sufficient combat power to strike a decisive blow and to facilitate a friendly transition to the offense. Corps defensive operations typically consist of five complementary elements--security operations, deep operations, main battle area, reserve operations, and rear operations.

Characteristics of the Defense

The basic characteristics of corps defensive operations include preparation, security, disruption, mass and concentration, and flexibility. The two primary forms of defense are mobile defense and area defense. Other forms are deliberate defense and hasty defense.

Preparation

In a deliberate defense, corps elements arrive in the AO before the enemy. This usually allows them the time necessary for adequate preparation. (Even in a hasty defense, corps units should enjoy a small advantage in preparation.)

During preparation, units conduct a thorough reconnaissance of the AO. They then prepare the terrain and their defensive positions to best defend against the enemy. The purpose of the corps' deception plan and aggressive OPSEC is to deny or deceive the enemy as to true friendly intentions. All units rehearse plans and contingencies.

Security

During decisive operations, the corps normally designates a security area, which has a covering force to provide early warning and to disrupt initial attacking enemy forces. However, not all situations dictate the need for a centrally controlled security zone. If not, the corps may delegate control of the security area to subordinate units to ensure adequate OPSEC.

In addition to the ACR conducting the corps' security operations, all units implement security measures within their AOs through deception and OPSEC. As technology proliferates, the corps' ability to protect the force and retain OPSEC becomes more difficult because of--

  • The threat of short and midrange ballistic and cruise missiles use, especially during the early stages of force-projection operations.
  • Widespread proliferation of advanced technology systems.
  • Greater media access, which provides near-real-time information to potential adversaries.

CONTENTS

FUNDAMENTALS OF CORPS DEFENSIVE OPERATIONS

Characteristics of the Defense

Forms of Defense

PLANNING CORPS DEFENSIVE OPERATIONS

Organization of the Defense

PREPARING FOR CORPS DEFENSIVE OPERATIONS

Intelligence

Maneuver

Fire Support

Air Defense

Mobility and Survivability

Combat Service Support

Command and Control

EXECUTING CORPS DEFENSIVE OPERATIONS

TRANSITIONING TO THE OFFENSE


Disruption

The corps disrupts the attacker's tempo and synchronization to prevent him from massing his combat power at the point of attack by--

  • Employing all precision fires, both lethal and nonlethal, before the enemy arrives in the MBA.
  • Defeating or misleading enemy reconnaissance forces.
  • Conducting deep operations that destroy critical support infrastructure, fire support assets, C2 nodes, and AD sites.
  • Disrupting or destroying key formations or their timely introduction into the battle.
  • Conducting C2W operations that strike at the heart of enemy C2 systems.
  • Coordinating with the joint team to synchronize joint assets. Conducting spoiling attacks that preempt enemy attacks.

The attacking enemy must never be allowed to set. Even if he makes temporary gains in an area defense, the friendly force must counterattack the enemy's penetration before he can consolidate his gains. Commanders must also plan to mitigate the disruptive effects of enemy attacks, especially against weapons of mass destruction.

Mass and Concentration

The corps seeks to mass the effects of overwhelming combat power at the decisive point to defeat the enemy attack. In mobile defense, the striking force is the principal vehicle by which the corps commander generates the effects of overwhelming combat power. In area defense, the corps selects EAs where it can defeat the enemy by massing the effects of overwhelming combat power from mutually supporting positions. Committing the reserve is one way of quickly generating mass.

The threat may force the corps to repeatedly mass to counter new enemy thrusts. The commander then employs economy of force measures in less critical sectors to generate mass at decisive points. Obstacles, security forces, and fires help reduce risks from economy of force measures.

Flexibility

Tactical flexibility stems from detailed planning (particularly in IPB), a clear and concise commander's intent, and rehearsals. Flexibility enables the commander to quickly shift the corps' main effort without losing synchronization.

Constituting and utilizing a reserve in every operation allows the commander to gain initiative and preserve flexibility. Selecting a COA that facilitates a number of branch plans or contingencies also enhances flexibility. Centralized planning and decentralized execution allow subordinate commanders to act independently within the commander's intent. Last, the corps' defensive plan must facilitate a rapid transition to the offense.

Forms of Defense

The two primary forms of defense are mobile and area defense. They apply at both the tactical and operational levels of war. The major difference between the two is the orientation of the defense. The mobile defense orients on the destruction of the enemy force. (See Figure 6-1.) The area defense orients on terrain retention.

Mobile Defense

The mobile defense employs a combination of fire and maneuver, offense, defense, and delay to defeat enemy attacks. It includes--

  • Forces conducting an area defense or delay to shape the enemy penetration.
  • A mobile striking force.
  • A reserve, if resources permit.

The mobile striking force conducts the decisive attack against a penetrating enemy force. The mobile striking force should possess greater combat power than that of the enemy force it is seeking to defeat or destroy and be capable of equal or greater mobility. The mobile striking force generally utilizes an indirect approach. It strikes the rear or an exposed flank of the enemy force, bringing to bear the effects of overwhelming combat power.

The corps commander allocates the minimum force to the area defense. He allocates the maximum available combat power to the mobile striking force whose mission it is to destroy or defeat the enemy that is attacking area defense forces.

Simultaneous with the attack of the striking force, corps deep operations continue to attack the enemy throughout the depth of his forces with both lethal and nonlethal systems. Mobile defenses generally require considerable depth.

The corps trades terrain for maximum effect to divert attention from the friendly main force and to overextend the attacker. Allowing the attacker to gain terrain diminishes his ability to react to the striking force.

The mobile defense may be a high-risk defense; therefore, the higher headquarters must know what form of defense subordinate units are using.

Area Defense

The corps conducts an area defense to deny the enemy access to designated terrain or facilities for a specified time. Commanders organize the area defense around a static framework of defensive positions (forward and/or in-depth), seeking to defeat enemy forces with interlocking fires and synchronized joint fires. Subordinate units conduct an area defense as part of the corps' mobile defense, employing local counterattacks against enemy units penetrating between defensive positions.

The depth of the defense varies according to the situation. Commanders position their forces in platoon, company, and battalion battle positions on suitable terrain with specific orientation and direction of fire or in sectors. Occasionally, depending on METT-T factors, a commander might direct the construction of a strongpoint. The corps commander generally retains a reserve of up to one-third of his combat power.

PLANNING CORPS DEFENSIVE OPERATIONS

Organization of the Defense

The AO must be large enough to allow the corps and subordinate units to conduct operations in depth. The corps commander may organize the AO in a linear manner or have units operate in noncontiguous AOs per METT-T. In either case, commanders generally organize their defensive sectors into five complementary elements:

1. A security operation forward and to the flanks of the corps' MBA.

2. A continuous deep operation against specific targets and/or organizations within the corps' sector.

3. The MBA.

4. Reserve operations in support of the MBA.

5. Rear operations necessary to ensure continuity of support.

This defensive organization does not dictate a sequential operation, rather it facilitates simultaneous operations in depth, tactical responsibilities, and a better understanding of the battlefield. The close fight is usually the decisive fight, but not always. Deep operations might, therefore, be decisive.

Security Force Operations

The corps typically conducts security force operations to its front (forward of the FEBA) and flanks. The security force generally operates under corps control, but may be delegated to subordinate MBA units within their assigned sectors. However, security operations normally provide support where the corps commander intends to defeat or destroy the enemy.

Security force operations normally support the commander's intent of where he wants to defeat or destroy the enemy. Traditionally, this is the close operation. However, the commander must also synchronize security force operations with all aspects of operations in depth. It may be the corps' first opportunity to seize the initiative from the attacking enemy.

In addition to identifying the main effort and attritting lead echelons, the security force's mission might be to shape the enemy's penetration. Security operations are similar for both mobile and area defense, except that in the mobile defense, the corps commander normally retains control of the covering force to ensure unity of effort in shaping the penetration. The corps commander then assigns the security force screen, guard, or cover missions.

Screen Mission. The corps commander assigns the security force a screen mission when covering a large area. The screen, deploying forward of the FEBA, provides the least degree of security. Missions include--

  • Providing early warning to MBA units to protect them from surprise and provide time for them to reposition forces to meet the enemy attack.
  • Delaying and harassing the enemy with supporting indirect fires.
  • Destroying enemy reconnaissance elements within its capability to deny the enemy information regarding friendly MBA defensive positions.

The screening force is a combined-arms force consisting of a mix of ground and air maneuver units. If the screen is under corps control, the ACR is the unit best suited to conduct this particular mission. Otherwise, a composite combined-arms organization should be formed.

Guard Mission. The guard mission accomplishes all tasks of a screen mission and prevents enemy engagement of the main body through combat operations. The guard force operates within supporting range of the main body.

Cover Mission. The cover mission accomplishes all the tasks of a guard mission except that it operates as a tactically self-contained force, apart from the main body. Typically, the corps controls the covering force. When it delegates control of covering force operations to subordinate MBA divisions, they usually employ brigade-size elements in that role.

A covering force conducts operations to either defend against or delay an attacking enemy force. The covering force's mission dictates whether it will conduct a delay or defense.

When a commander uses a strong covering force with adequate depth, the covering force can expect to fight a major engagement. It might also defend rather than delay, which would cause follow-on enemy forces to commit themselves to a particular action, thus disclosing their main attack.

If the covering force's mission is to defend, tasks include the specific enemy force it is expected to defeat or to destroy before battle handover. In a delay operation, the corps commander will state whether the covering force is to delay forward of a specific terrain feature for a specified time (high risk) or whether preservation of the force (low risk) is of primary importance.

Tasks inherent to a covering force might include--

  • Forcing the enemy to prematurely deploy and commence his attack.
  • Identifying the enemy's main effort.
  • Reducing the enemy's strength by either destroying specific maneuver units and/or stripping away essential assets (FA, ADA, engineer units, for example).
  • Shaping the penetration of the enemy's attack.

In many situations, the ACR is well-suited to conduct corps covering force operations. In some situations, such as those involving irregular forces in restrictive terrain, the covering force may require other type forces capable of conducting covering force operations. Such forces would include maneuver divisions or a division-size force consisting of ground and aviation brigades. The corps uses its organic surveillance means, reports from the covering force, and higher level intelligence inputs to determine (or confirm) the axis and strength of the enemy main attack.

If possible, the covering force causes the enemy's lead divisions to become decisively engaged while attempting to penetrate the covering force area (CFA). This may reveal the intended location of the main attack and will alter the rate at which enemy forces close on the MBA.

The covering force might also cause the commitment of follow-on forces by either defeating or destroying lead units. If possible, the CFA should be deep enough that the enemy's artillery would have to displace to subsequently range MBA forces. This action would significantly lessen the effectiveness of enemy preparatory fires and reduce the number of artillery weapons immediately available to the enemy commander as the MBA battle is joined.

Deliberate targeting of specific elements of the attacking formation by the covering force aids MBA defense. It destroys the enemy force's combined arms integrity and damages his ability to react once he arrives in the MBA. Specifically, priority targets for the covering force often include enemy reconnaissance units, AD systems, CL vehicles, obstacle breaching equipment, and NBC-capable delivery systems.

Destroying accompanying AD systems in the CFA improves the capability of attack helicopters and USAF aircraft to attack in depth. Destruction of AD radars, which electronic intelligence systems locate, denies the enemy the capability to direct his own AD systems. Destruction of enemy obstacle clearing assets reduces his breaching capability before arrival in the MBA. Both the physical destruction of key CL equipment and the nonlethal electronic attack against key enemy C2 elements disrupt the enemy's ability to synchronize current and future operations.

The corps enhances unity of effort when it controls the covering force. Considerations include the form of defense, the size of the sector, the commander's ability to communicate with subordinate units, the availability of controlling headquarters, and the number of units operating in the area. When the corps controls the covering force, subordinate MBA units maintain liaison with units operating to their front. In this situation MBA units should--

  • Monitor covering force radio nets to get a picture of the battle.
  • Establish and maintain liaison with covering force units forward of their positions.
  • Prepare for actions at the battle handover line (BHL).
  • Maintain liaison during passage of covering force units.

Commanders should only delegate control of the covering force to subordinate units by exception. Having separate MBA unit-controlled covering forces tends to slow reporting and to fragment the corps commander's overall view of the battle. Separate control also makes a coordinated covering-force fight harder to conduct and divides the attention of MBA commanders between the covering force and the MBA fight.

Normally, additional combat, CS, and CSS units augment the covering force. Typical support includes additional FA, aviation, engineer, AD, NBC, reconnaissance, and smoke generator units. Separate brigades conducting covering force operations require less augmentation than division brigades, as the latter lack organic CS and CSS assets. Screen operations do not require extensive augmentation because they derive support from the main body.

Only CSS assets immediately essential to the operation (fuel, ammunition, medical, and limited maintenance) position themselves forward in the CFA. Such assets withdraw when no longer required or the risk of their loss becomes unacceptably high.

Combat service support for the covering force with a defend mission requires pre-positioning supplies, forward positioning of maintenance, and large quantities of obstacle materials and ammunition. A delay mission requires less time for terrain preparation, but pre-positioning supplies at subsequent delay lines or positions is still critical to support the planned operation.

A key aspect of any security force operation is battle handover. To aid in control of handing the battle over to the MBA unit, the corps establishes a PL designated as the BHL. The MBA commander . and the security force commander coordinate the location of the line and recommend its location to the higher commander. However, it remains the corps commander's responsibility to establish the line.

The MBA commander controls the ground forward of the FEBA out to the BHL. He places security forces, obstacles, or fires in this area to canalize the enemy and facilitate the withdrawal of security force elements.

The BHL is also where control of the battle passes from the security force to the MBA force. Typically it is forward of the FEBA. Main battle area forces can then bring direct fires to bear on the enemy to facilitate security force activities, such as disengagement, withdrawal, or passage of lines.

Security force and MBA units coordinate specific passage lanes and other details. When possible, the boundaries of security force units coincide with those of MBA units.

When directed to do so, the security force hands over the battle to MBA forces, then moves to a designated area and prepares for future operations. This normally will be a position deeper in the MBA or in the corps rear where there will be time to rearm, refuel, or reconstitute, if necessary. The security force passes through MBA units as quickly as possible to minimize their vulnerability to indirect fires.

Security to the corps flanks during the defense is the inherent responsibility of the committed maneuver units within their AO. However, the corps may task a specific unit to provide security if the corps flank is significantly vulnerable. The corps may also task a specific unit to provide security if the corps has accepted risk in the MBA with an economy of force operation not having sufficient forces to perform the flank security mission. A flank security force's typical missions in the defense are either screen or guard missions.

Deep Operations

Many of the aspects of corps deep operations in offensive operations (Chapter 5) also apply in corps defensive operations. Overall, corps deep operations in the defense help achieve depth and simultaneity and secure advantages for future operations. Deep operations disrupt the enemy's approach to and movement in the MBA, destroy high-payoff targets, and deny or interrupt vital components of enemy operating systems. Some key high-payoff targets will be the enemy's trailing or reserve echelons, HIMAD sites, key C2 nodes, and key infrastructure.

As in offensive operations, the deep fight may be decisive--defeating or deterring the enemy before he can reach MBA forces. The corps controls deep operations similarly to its control of offensive operations. However, it might designate the FSCL closer to the FEBA to better facilitate joint fires.

Close Operations

Ultimately, the MBA force's mission is to defeat the enemy attack or to destroy the attacking enemy force. Missions cover the entire spectrum of operations-defending, delaying, attacking, or performing in an economy of force role. Units also conduct forward and rearward passages of lines. However, they normally avoid being bypassed unless it fits within the corps commander's intent.

Mobile Defense. The corps conduct a mobile defense when it orients on the enemy force as opposed to retaining terrain. METT-T conditions may dictate that the corps conducts a mobile defense in two instances: when defending a large AO against a mobile enemy force, or when defending against an enemy force with greater combat power, but less mobility. A mobile defense incurs great risk, but also stands a greater chance of inflicting a decisive defeat and even destroying the enemy force.

Both corps and divisions conduct mobile defenses. When the corps conducts one, subordinate units generally conduct an area defense or delay to shape the penetration or attack as part of the corps striking force. Commanders generally do not assign the mission of a mobile defense to subordinate units except in an economy of force role.

The corps commander may choose to shape the battlefield by defending in one sector, to deny terrain to the enemy while delaying in another to create the illusion of success. This perceived enemy success in the delaying sector may create an opportunity for the striking force to attack. The corps may also entice the advancing enemy into an engagement area by appearing to uncover or weakly defend an area into which the enemy desires to move.

Critical to the mobile defense's success is the commander's vision of the battlefield and the time and place he chooses for the striking force to attack. Visualization of the battlefield includes a decisive point. That is, an advantage point on the battlefield where the commander foresees allowing the enemy to proceed in order for the striking force to accomplish its mission.

A force-oriented objective or engagement area usually indicates a decisive point. The staff synchronizes the corps' activities in time and space to sufficiently mass striking force effects at the right time and place.

The striking force is a self-sufficient, task-organized, combined-arms unit. It is a committed force, not a reserve. The object of a striking force's attack normally is to inflict a decisive defeat on the enemy.

Maneuver (fires coupled with movement) can achieve decisive defeat. It is also possible to decisively defeat the enemy by massing fires from a position that allows excellent observation and fields of fire.

Spoiling attacks help break up the enemy's momentum, disrupt his timetable, cause him to shift his forces, or just buy time for friendly forces. A striking force's components should include the maximum combat power available to the commander at the time of the attack. At a minimum, it should have equal or greater combat power than the force which it must defeat or destroy. Fire support assets can offset maneuver force shortfalls.

When conducting a mobile defense, the corps commander may need to commit his reserves to help defending units shape the battlefield. Attack helicopters are ideal for this role. The commander must not commit his striking force except to deliver the decisive blow to the enemy force. The striking force becomes the main effort upon commitment.

The corps designates obstacle-restricted zones that allow subordinate units flexibility and guidance. Corps topographic engineering provides the needed terrain products to support the IPB process. Specific terrain analysis products assist in maneuver planning and in designing obstacle systems to complement maneuver plans. Priority of effort for the mobile defense is to mobility for the striking force and to countermobility for units conducting an area defense. Engineers prepare necessary strongpoints and help units improve survivability positions.

Area Defense. The corps conducts an area defense when the orientation of the defense is to deny the enemy designated terrain for a specified time. In an area defense, the corps commander allocates sufficient combat power against enemy avenues of approach to achieve a reasonable chance of success, even without the commitment of the reserve. He assumes risk in less threatened sectors and allocates forces in an economy of force role. Maneuver within an area defense usually consists of repositioning within defensive positions or sectors and counterattacks.

Commanders conducting an area defense plan for counterattacks by their reserves. They plan spoiling attacks and counterattacks to disrupt the enemy and to prevent him from massing or exploiting success. They also conduct contingency planning to counter assumed enemy penetrations of forward defenses.

The priority of effort for engineer operations in the area defense is survivability and/or countermobility operations. Units concentrate on terrain reinforcement and emplacing obstacles to turn, fix, block, or disrupt enemy forces. As in the mobile defense, engineers also prepare required strongpoints and help units improve survivability positions.

Sustained combat in the MBA normally generates the largest requirement for supplies and services. In a protracted defense, the corps' ability to sustain its forces significantly influences the battle's outcome. The defense of the MBA requires a mix of forward-deployed and echeloned logistic units to allow for orderly withdrawal or advance.

Combat service support efforts must stress adequate supply of fuel and ammunition, rapid evacuation of wounded, and repair as far forward as possible. The emphasis is on maintaining the corps at the highest level of combat power possible. Only by doing this can the corps hope to have the strength to transition to an effective offense.

Planning considerations and operational techniques to improve CSS to defending units include--

  • Selecting ammunition transfer points (ATP) and pre-positioning limited stockages of ammunition in the MBA.
  • Displacing from rear areas, on a scheduled basis, push packages of certain critical items (ammunition, NBC defense supplies, POL, and selected repair parts) so interruptions in communications do not disrupt the flow of supplies.
  • Prepackaging Class IV and Class V obstacle material (normally requisitioned items) into brigade-size push packages to expedite delivery.
  • Conducting resupply operations during periods of limited visibility "to reduce chances of enemy interference.
  • Echeloning CSS units in depth throughout the defensive area to allow for continued limited support.
  • Employing and dispatching maintenance support teams as far forward as possible to reduce unit evacuation requirements to a minimum and to fix the force as far forward as possible.

Reserve Operations

The corps retains a reserve in either form of defense. The reserve is an uncommitted force available for commitment at the decisive moment. It provides flexibility for the commander through offensive action. The reserve is more difficult to resource in the mobile defense because so much of the corps' combat power is allocated to the striking force.

The reserve can be as large as one-third of the combat power, but normally not smaller than a brigade-size element. If needed, the reserve is the corps commander's principal means of influencing the close fight. It is usually supported with additional assets (artillery, CAS, attack helicopters, IEW assets, engineer, chemical, CSS).

Once the commander commits the reserve, it generally is the corps' main effort. Once a reserve becomes committed, the commander designates another reserve.

Reserves must be available to counterattack by fire or by fire and maneuver. The corps commander's intent should specify whether the reserve is to counterattack by fire or assault the objective or enemy force. The reserve must remain agile in order to respond to a penetration that has occurred earlier than, or at a different location than, that visualized by the senior commander.

Ideally, units launch local counterattacks immediately after attacking forces enter the position and have not had time to reorganize and establish themselves or maintain the operational tempo that allowed them to penetrate. Since this period is relatively short, the force must judiciously deliver counterattacks on the local commander's initiative. The object is to block the enemy penetration, defeat the enemy attack, eject the enemy force, and restore conditions necessary to support the senior commander's concept and intent.

The reserve's normal composition includes armored, mechanized, and/or aviation forces. However, the reserve may also include AASLT forces supported by attack helicopters and CAS if the concept for their employment calls only for a relatively short operation, a quick linkup by heavy forces, or an extraction.

The reserve may also employ light forces in restricted terrain. The corps aviation brigade HQ can be the reserve HQ for short periods when properly augmented.

The timely movement of reserves from their AAs to the point of commitment can be a major planning and execution problem. Although the main CP is responsible for reserve movement, deconfliction between maneuver and CSS movements in the corps rear is the rear CP's responsibility.

Rear Operations

The success of corps defensive operations may hinge on its success in conducting rear operations. Threat operations, ranging in size from individual saboteurs to enemy airborne or air assault insertions in the corps' rear, will target key corps units, facilities, and capabilities. These threat activities, especially at smaller unit levels, may even precede hostilities.

Corps defensive planning must address the early detection and immediate destruction of threat forces attempting to operate in the corps' rear. The operation may require additional emphasis on rear operations based on the form of defense. (See Appendix C for a discussion of corps rear operations planning considerations.)

The degree of risk the force accepts during a mobile defense invariably passes to the rear operations commander. This risk increases the threat to support forces and may impact their ability to continue operations at the anticipated level.

PREPARING FOR CORPS DEFENSIVE OPERATIONS

Intelligence

The corps G2 maximizes preparation time to fully employ and synchronize the corps' IEW architecture. Organic corps collection systems for a fully deployed MI brigade can detect and track enemy units out to approximately 200 kilometers. Beyond that, the corps relies on EAC, joint, and some national systems downlinked into the corps' HQ. The corps almost totally relies on EAC, joint, and national systems during the early stages of force-projection operations.

In the mobile defense, intelligence requirements focus on ascertaining precise enemy location, strength, and intent. The G2 must find the enemy's main avenue of approach and the location of his follow-on forces. Answers to these intelligence requirements allow the corps commander to properly array his forces in an economy of force role to defend or delay, shaping the battlefield for the counterattack by the strike force. This affords him the time necessary to precisely commit the striking force. The striking force commander must receive near-real time updates during the movement to contact to ensure he engages the enemy force at the desired time and place.

Intelligence in the area defense focuses on identifying where and when the corps commander can most decisively counterattack the enemy's main effort or exploit enemy vulnerabilities. Intelligence and EW support identifies, locates, and tracks the enemy's main attack. It provides the commander time to allocate sufficient combat power to strengthen the defense at the point of attack. Intelligence also identifies friendly vulnerabilities and key defensible terrain.

Maneuver

The corps commander's intent and the nature of the threat determine whether the corps conducts a mobile defense or an area defense. In many cases, the corps' mission statement specifies whether the corps is to conduct a force-oriented or terrain-oriented defense. If the corps is also a JTF headquarters or JFLCC, then the CJTF should have the flexibility to determine the form of defense. The corps must specify to its subordinate units whether they are to conduct a force- or terrain-oriented defense.

In the defense, the corps typically organizes the battlefield into deep, close, and rear AOs. Two additional concerns within close operations are security and reserve operations. Corps units might operate in noncontiguous AOs, which preclude a linear organization. This is normally the case when the corps' striking force executes a deep maneuver as part of a mobile defense. Deep operations initially focus on any of the following:

  • Selective high-payoff targets.
  • Isolating approaching enemy forces from its higher headquarters.
  • Supporting forces.
  • Attrition of enemy combat power.

In the MBA, the corps commander assigns defensive sectors. based on METT-T, to the units conducting an area defense or delaying against the penetrating enemy force. These are the forces that shape or defeat the enemy.

In a mobile defense, the commander may want to yield ground quickly to allow the enemy to think he has been successful or to entice him to a decisive point where the striking force can attack him. The corps commander may also select EAs where he desires to destroy the enemy. Commanders also use EAs to orient maneuver and fires for deep operations.

The striking force constitutes the maximum combat power available to the commander at the time of the attack. In a corps, this is normally a multiple-division force, under the corps commander's control. It can be as large as two-thirds of the combat power available to the corps at the time of the attack.

Before the main battle, the striking force withdraws to attack positions and prepares for the decisive attack. It may deploy all or some of its elements to--

  • Deceive the enemy as to the force's purpose.
  • Occupy dummy battle positions.
  • Create a false impression of unit boundaries (especially when operating with armored-light forces or multinational forces).

Deep maneuver by the striking force includes major logistic considerations, such as potentially establishing a forward logistic base (FLB). Deep maneuver by the striking force may be a component of the corps' deep operations.

The attack by the striking force should be part of a devastating attack in depth by the corps to isolate the penetrating enemy force and to defeat or destroy it, if possible. When facing a large penetrating enemy force, corps operations in depth may repeatedly isolate portions of the enemy force and attack them with the striking force.

An area defense is similar to a mobile defense except that its execution is more static. The reserve in an area defense is a combined-arms force that may be as large as one-third of the force. Spoiling attacks and counterattacks in an area defense disrupt the enemy and contain expected enemy penetrations. Subordinate commanders must also retain a reserve to rapidly contain, defeat, or block enemy forces before they can consolidate any gains.

An underlying purpose of all defensive operations is to create the opportunity to transition to the offense. Therefore, all contingency corps must be able to fight the heavy-light mix. Light infantry forces will likely conduct early deployment and secure the lodgement for follow-on armored and mechanized forces.

In an area defense, light infantry forces can defend in restricted terrain and along linear terrain features. They provide the TCF when adequate ground or air transportation is available.

If commanders anticipate contact with enemy armor, light infantry units should construct a strongpoint defense. Light infantry possesses an extremely limited capability to conduct counterattacks to restore a position or to repel a penetrating enemy force.

In a mobile defense, light forces generally conduct some form of area defense (including the strongpoint) to shape the penetration. The corps can air-insert light infantry as part of the striking force.

Assigning correct command and support relationships is critical to successful C2 of armored-light operations. This applies equally to combat, CS, and CSS units. However, augmenting a light force with CS and CSS assets from an armored formation may well create a heavy-light mix without task-organizing maneuver forces. For instance, using a corps FA brigade with self-propelled guns and rocket artillery systems in support of a light division raises many of the same considerations as attaching an armored brigade to a light division.

When combat assets are provided to a light force, they are normally assigned a support relationship that lessens the CSS burden on the light force. This ensures that the commander who provides the assets retains the flexibility to shift assets as the situation dictates. An armored brigade, normally OPCON to alleviate CSS responsibility, is the unit of choice to task-organize with a light division. Light forces are normally attached to armored units.

Combat service support assets are generally left under the parent headquarters' command and assigned a mission to support the light or armored-light force. As with CS assets, there are circumstances that dictate organizing CSS assets to the light force. In such cases, attachment is generally the best option.

The corps uses standard control measures when employing a mixed force. When coordinating with a light unit, the heavy unit commander must consider the differences in rates of movement, equipment, and operating procedures.

In some situations, commanders will have to change normal coordination procedures. The heavy unit will usually be responsible for coordinating with and providing liaison to light units because of the light units' lack of ground or air transportation.

Fire Support

Whether in an area defense or mobile defense, fire support weights the main effort. In an area defense the main effort is where the defense is responsible for covering the enemy's main avenue of approach. The main effort in a mobile defense is the striking force. One consideration in a mobile defense is the defending force's ability to provide continuous and massed fire support to the striking force.

When the striking force is to attack beyond conventional artillery range, the commander plans for the forward displacement of artillery assets or the incorporation of artillery into the striking force. Fire support assets can be critical when off-setting a lack of maneuver assets in the striking force.

Commanders must employ fire support assets with decisive effects once the striking force initiates contact with the penetrating enemy force. A significant percentage of CAS sorties should also support the striking force. Nuclear weapons, if employed, obviously can severely disrupt the enemy force before the striking force initiates contact.

Deliberate planning and massing of fires is difficult for the striking force in a mobile defense. Both the striking force and the enemy must move to the point of engagement. Therefore, determining the precise point of battle is more difficult than in an area defense where the friendly force is static and the point of engagement is planned. Commanders must take precautions to prevent incidents of fratricide as the striking force nears the EA while supporting air is conducting interdiction and CAS.

Air Defense

In the area defense, the commander seeks to place an AD umbrella over his command with particular emphasis on critical nodes. He normally accomplishes this with static placement of AD assets.

In the mobile defense, the movement of the striking force complicates this, especially when it must attack beyond the range of AD coverage. Based on threat capabilities, the commander must prioritize his assets to protect both the static defending forces and the striking force.

HIMAD assets generally remain deployed behind the static forces unless the striking force is attacking a deep objective. Then, HIMAD assets may need to jump to a forward base, if established. Forward area air defense assets should thoroughly integrate into maneuver assets of both the striking force and the defending force. Commanders must also consider counter air operations for defense of the striking force.

Mobility and Survivability

The corps' topographic unit provides detailed terrain analysis that, when used with the concept of maneuver and other staff products, provides guidance for obstacle planning. In the mobile defense, the corps places greater restrictions on obstacle emplacement by its subordinate units.

When necessary, the corps assists subordinate units in forward staging of Class IV obstacle material and Class V mines and demolitions. Corps engineer assets also provide most of the general engineering in the corps rear area to improve LOCs, support areas, infrastructure, and so on.

As with fire support assets, engineer assets resource both the striking force and the more static defending forces in a mobile defense. Priority of effort for the striking force is to mobility and then countermobility operations. The priority of effort for defending forces is survivability and/or countermobility.

The corps ensures that subordinate obstacle plans limit enemy maneuver while still permitting the rapid attack of the striking force. Remotely delivered mines are critical to completing the obstacle plan in shaping the battlefield in front of the attacking enemy force.

The striking force may attack through a short-duration, scatterable minefield after the mines have self-destructed. The striking force must ensure the axis of advance is clear or conduct an in-stride breach, if necessary.

Commanders should task-organize engineer units with reconnaissance elements in front of the striking force. Highly mobile engineer forces should be well-forward and integrate into the striking force's leading maneuver formations.

Follow-on engineers conduct route improvement, replace assault bridges with other bridges, and expand obstacle breaches. Engineers with flank units focus on countermobility to impede potential enemy counterattacks. Corps engineers in the corps rear area perform general engineering functions.

Military police contribute to mobility by conducting battlefield circulation control (BCC). Military police also enhance battlefield survivability by conducting area security and defeating rear area threats during response-force operations.

Chemical personnel contribute to survivability, perform vulnerability assessments, and recommend actions to commanders. For example, obscurants defeat threat sensors and aid in deception planning as well as in camouflage and concealment.

Combat Service Support

The greater the distance the striking force attacks from main defensive positions, the greater the amount of supplies the force will need. The defending force will require significant quantities of barrier material and ammunition; the striking force will require greater amounts of fuel, ammunition, and maintenance.

Medical evacuation from the striking force area poses significant challenges. When the striking force is at a significant distance from the support bases, CSS units must secure an FLB. The commander must designate his priorities for CSS and consider any changes in priorities and when they might occur.

Command and Control

When conducting a mobile defense, the corps generally retains control of the covering force operation, the area defense, and the attack by the striking force to ensure synchronization and unity of effort. The corps commander provides the striking force commander the decisive point, objective, or EA where the corps commander desires the striking force to destroy the enemy. The corps commander provides the anticipated size and composition of the penetrating enemy force as well as provide complete supporting graphics (especially obstacle emplacements).

When the penetrating enemy force reaches the decision point to commit the striking force, the commander provides updated information on any changes, even as the striking force is moving to attack the penetrating enemy force. The signal support system will be challenged to meet the demands of a fluid mobile defense.

Accepting risk is a critical aspect of a mobile defense. The defending force retains the bulk of the combat power in the striking force. The corps commander only allocates sufficient forces for the area defense to shape the battlefield.

The risks are twofold. First, static or defending forces usually are insufficient in strength to defeat the enemy alone. Therefore, the mobile defense's success depends on the successful commitment of the striking force. Second, the force may not be able to entice or maneuver the enemy into the area the defending commander intends. This might preclude the decisive employment of the striking force.

In an area defense, subordinate echelons normally exercise a greater degree of autonomy than in the mobile defense. Depending on the size of the sector, subordinate echelons may control the bulk of the reserves. The corps may only retain a small, highly mobile reserve.

Subordinate commanders fight their engagements within their AOs, and the senior commander retains a reserve to assist the most threatened sector. There usually is less risk because commanders should have adequate forces to defend the AO and stand a reasonable chance of defeating the enemy, even without committing the reserve. They usually accept greater risk in less critical sectors.

EXECUTING CORPS DEFENSIVE OPERATIONS

On 8 August 1990, the XVIII Airborne Corps assault CP and the lead elements of the 82d Airborne Division deployed to Saudi Arabia initiating Operation Desert Shield. The corps deployed three divisions within 60 days (82d Airborne, 101st Air Assault, and the 24th ID(M)).

The remainder of the corps (3d ACR, 1st Cavalry Division, 75th Field Artillery Brigade, and the 212th Field Artillery Brigade) arrived by 1 November. The corps defense increased in capability with the arrival of each unit in theater. As additional units arrived, corps plans (called Desert Dragon I, II, and III) were revised.

Desert Dragon I was the initial corps lodgement defense to protect the A/SPODs at Dhahran and Ad-Dammam with a reinforced airborne brigade. Desert Dragon II expanded the lodgement area to include the port of Al-Jubayl to protect the arrival of the 7th Marine Expeditionary Brigade (Figure 6-2).

In Desert Dragon I and II, the lodgement defense was heavily outnumbered by the Iraqis armored forces. The airborne brigades optimized four factors to enhance their defensive combat power:

1. They situated their defenses at points along the coast roads closely bordered by sabkhas (coastal salt flats), which minimized off-road maneuver by enemy armored forces.

2. They optimized their direct-fire range advantage over the Iraqis with tube-launched, optically tracked, wire-guided (TOW) missiles and Sheridan tanks.

3. The defense was supported by attack helicopters and USAF CAS interdiction.

4. The soldiers were disciplined and sufficiently confident in their units to withstand the shock of an armored attack.

Shortly after the arrival of the lead elements of the 24th ID(M), the corps transitioned to Desert Dragon III. This also signaled an end to any reasonable chance of success for an Iraqi attack into Saudi Arabia. The plan took its final form with the arrival of the 1st Cavalry Division.

The corps would conduct a mobile defense in sector with a division-size striking force (Figure 6-3). A provisional Arab mechanized division, designated the Eastern Area Command, would conduct the initial defense of Saudi Arabia forward of the corps covering force. The Marines would conduct an area defense of the Al-Jubayl coastal region.

The 101st Airborne (Air Assault) Division, augmented by the 3d ACR and the 12th Aviation Brigade, would conduct covering force operations in AOs Carentan and Normandy. The 24th ID(M) was to conduct an area defense within the MBA. The 82d Airborne Division conducted an area defense of critical installations and facilities.

The 1st Cavalry Division was designated as the corps striking force (called the reserve at that time) with the principal mission to counterattack into flanks and rear of the trailing echelon brigades and divisions, presumably the Republican Guard forces. Corps deep operations would focus on attacking select high-value targets as well as follow-on Iraqi echelons in order to attrit and disrupt them.

On 17 January 1991 corps units transitioned to offensive operations. Attack helicopters from the 10lst Airborne (Air Assault) Division conducted a deep attack in conjunction with joint forces and destroyed a critical ground control intercept radar in Western Iraq to open the air campaign of Operation Desert Storm.

The corps remained in eastern Saudi Arabia until shortly before the initiation of the ground offensive in order to deceive the Iraqis as to the true location on the concept the corps adopts to achieve attack of the coalition's attack.

TRANSITIONING TO THE OFFENSE

Planning considerations for transitioning from the defense to the offense are based on the following situation:

  • The enemy attack against the corps has reached its culminating point.
  • The enemy is transitioning into a hasty defense.
  • The corps has sufficient assets to accomplish its assigned offensive mission.

Commanders plan for a sequel to offensive operations in advance, preferably before the defensive battle begins. The transition must be timely and rapid to keep the enemy from establishing prepared defenses and/or receiving reinforcements. In many instances, the attack against such an enemy will complete his defeat and/or destruction.

In a mobile defense, transitioning to the offense for the corps generally follows the striking force's attack. In an area defense, the corps designates a portion of its units to conduct the attack, depending objectives.

The attack may consist of units not in contact (corps reserves and newly assigned units) or units currently in positions along the LC (defending MBA units) or both. Using units not currently in contact is the preferred option, since defending MBA units may still be decisively engaged.

Another consideration of using units not in contact occurs when they are operating in noncontiguous AOs. The corps would then rapidly mass the effects of overwhelming combat power with the main effort. This might require the commander to adopt economy of force measures in some AOs while temporarily abandoning others in order to generate sufficient combat power. (See Chapters 5 and 7 for planning considerations for the commitment of these units.)

If units in contact also participate in the attack, the corps commander must retain sufficient forces in contact to fix the enemy. He concentrates for the attack by reinforcing select subordinate units (divisions and separate brigades) so they can execute the attack and, if necessary, maintain the existing defense. He can also adjust the defensive boundaries of subordinate units so entire units (preferably brigade size, but no smaller than battalion) can withdraw and concentrate for the attack.



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