Military

CHAPTER 4

MORTARS IN SUPPORT OF OFFENSIVE
OPERATIONS

Offensive operations carry the fight to the enemy. The main reason for attacking is to destroy enemy forces. The mortar platoon participates as part of a larger force in the conduct of offensive operations. Mortars are an integral part of any attack and can be used to do the following:

  • Neutralize, suppress, or destroy enemy forces.
  • Deprive the enemy of resources or the use of decisive terrain.
  • Fix the enemy in position.
  • Deceive or divert the enemy.
  • Provide screening or obscuration.
  • Provide battlefield illumination.

4-1. HISTORICAL EXAMPLE

An excellent example of the integrated use of mortars to support an infantry attack occurred during the operations of Company C, 39th Infantry Regiment, 9th Infantry Division at Cherbourg, France, in June 1944 (Figures 4-1 and 4-2.)

a. Company C was leading the 39th Regiment's advance, with its 1st and 3d platoons in front and 2d platoon trailing. Suddenly, the Germans opened fire with flak cannon and machine guns from hidden positions. The 1st and 3d platoons were pinned down, unable to move. At the same time, German mortars and artillery began to fall on the 2d platoon and the company command group.

b. The company commander took the 2d platoon and a machine gun section with him and tried a sweeping maneuver to the right. He was unable to get any farther forward than the right flank of the 3d platoon. With all its rifle platoons pinned down by close and accurate enemy direct fire, the company was facing heavy casualties.

c. Fortunately, the weapons platoon had placed its three 60-mm mortars into action and began to deliver fires on the German positions. The 81-mm mortar platoon of the heavy weapons company also assumed firing positions and began to adjust fire onto the enemy.

d. With the combined assistance of its own 60-mm mortar platoon, the 81-mm mortar platoon from Hvy Wpns Company, and the 60-mm mortar platoons of its sister E and F companies, and aided later by the 26th FA battalion, C Company riflemen were able to move forward again to close with the enemy. After several hours of bitter fighting, during which hundreds of mortar rounds were fired, the enemy broke. By 2400 hours the position was clear.

e. The commander later credited the immediate and accurate mortar fire from his weapons platoon with saving the company during those first critical moments. He said the combined fire of the battalion's other mortars and the field artillery "broke the back" of a determined enemy resistance. Because they were organic, the company's mortars were able to deliver fires faster and closer than the artillery. Their fires complemented and supplemented the heavier FA fires.

4-2. MORTAR SUPPORT DURING OFFENSIVE OPERATIONS

Offensive operations are characterized by movement and changing situations. Flexibility in fire support is required to provide continuous fires. The mortar platoon plans to conduct fires en route to the objective, on the objective, and beyond the objective (Figures 4-3 and 4-4).

a. Mortars accomplish this by positioning near the LD using the one-half to two-thirds maximum range rule as a guide, and then moving forward. Having mortar firing positions in deep defilade is often more important than the one-half to two-thirds maximum range rule. If a good defilade position is located closer to the LD, it should be used.

b. Mortars provide support during the attack to neutralize, suppress, or destroy the enemy while the assault element moves to the final coordination line, screens friendly movement by obscuring the enemy's vision, neutralizes resistance during the final assault, and isolates the objective.

c. Mortars neutralize and suppress enemy defenses during the final phase of the attack by short, violent preparations targeted against frontline defenses and OPs. Mortar fires are lifted or shifted at the last possible moment before assault elements close on the enemy's position.

d. Once an objective is seized, friendly forces consolidate and prepare to repulse enemy counterattacks or to reorganize with minimum loss of momentum to continue the attack. Mortars protect friendly troops during consolidation or reorganization by preventing enemy reinforcements from entering the objective area or by breaking up enemy counterattacks.

4-3. TYPES OF OFFENSIVE OPERATIONS

There are five major types of offensive operations that mortars can expect to support. In many ways, mortars support each type of operation in the same manner.

a. Movement to Contact. Movement to contact gains or reestablishes contact with the enemy to further develop the tactical situation. The exact location of the enemy is usually not known.

(1) Mortars provide the maneuver commander the most responsive means of indirect fire support during a movement to contact. The displacement techniques used by a mortar platoon during this operation depend on the distance to be traveled, the likelihood of enemy contact, and or the maneuver commander's guidance. For example, if the objective in a movement to contact is distant, the entire mortar platoon can be directed to displace, moving close behind a maneuver element, depending on where enemy contact is expected. While the mortar platoon, section, section (-), or squad is displacing, it must be prepared to immediately engage targets using direct-lay, direct-alignment, or hip-shoot techniques of engagement.

(2) Fire planning on key terrain and likely enemy positions increases mortar responsiveness upon enemy contact. It must include possible targets en route to the march objective, on the march objective, and beyond. Once enemy contact is made, the mortar platoon leader quickly issues a FRAGO to support the maneuver element's hasty attack or bypass.

(3) Not only must the commander plan mortar fires, but he must also plan mortar movement. The mortar platoon can be attached, for movement, to a company near the front of the battalion march column or tactical formation. This will ensure that the mortars are close enough to the enemy to contribute responsive, immediate fires (See Figures 4-5 to 4-9 for examples of mortar platoons and sections moving within unit formations.)

b. Hasty Attack. The hasty attack uses maximum firepower and rapid movement to maintain momentum. There is usually little or no time for planning additional fire support. Most targets engaged by mortars are targets of opportunity. However, planned fires for the movement to contact or the defense increase mortar responsiveness when engaging enemy positions on or near planned targets.

(1) Once contact has occurred and the commander decides to attack, the mortar platoon leader issues fragmentary orders. He quickly positions any moving elements in defilade and provides maximum indirect fires. Properly positioned and employed, mortars aid the maneuver commander in maintaining the momentum of the attack.

(2) After a successful hasty attack, mortars must be resupplied quickly. This enables them to effectively support a continuation of the attack, to protect against a counterattack, or to transition to the defense. Any movement during this phase of the operation is conducted quickly to minimize the maneuver element's vulnerability to a counterattack.

c. Deliberate Attack. The deliberate attack requires more planning time, detailed intelligence, and a more detailed scheme of maneuver, including the plan for fire support.

(1) The mortar platoon is normally directed to deliver heavy, precisely timed fires on specific targets. Company mortars may be included in these fires or may be held for use against unplanned targets that appear. The platoon leader considers preparation of ammunition, registration, and resupply. Use of prestocked ammunition, where possible, allows the mortar platoon to save its basic/combat load for the continuing attack.

(2) One common form of maneuver during a deliberate attack is the penetration. The battalion must mass combat power against an isolated, narrow portion of the enemy front. Concentrated direct and indirect fires are used as the assaulting force closes on the enemy's forward defensive positions. At some point, the forward movement of the assault element masks the direct fires of supporting weapons. The mortar platoon's massed indirect fires keep the enemy suppressed while the rifle platoons assault to destroy him. The commander of the assaulting force controls this massed mortar fire and shifts it at the last minute onto the rear of the enemy defensive position, likely routes of withdrawal, support by fire positions, and likely counterattack routes. The mortar platoon leader must be prepared to fire large volumes of ammunition near friendly forces. This requires detailed planning and close supervision by mortar leaders at all levels. (See appendix B for detailed information on target effects planning.) Extraordinary amounts of HE ammunition are required to suppress or destroy defenders in properly prepared defensive positions.

(3) Mortars support the consolidation of the objective the same as in a hasty attack.

d. Exploitation. An exploitation follows a successful attack. It destroys the enemy's defenses and keeps him disorganized so he cannot resupply or regroup his forces. An exploitation requires rapid advance and violent action.

(1) In the exploitation, fragmentary orders are common. The operation may require changes in the direction of attack to ensure destruction of the enemy. There may be many small groups of enemy that are bypassed, which can pose a threat to the security of the mortar platoon. The mortar platoon provides its own security and may even be involved in taking and guarding PWs.

(4) Due to the speed with which an exploitation is conducted, mortars can be directed to move by platoon or section with, or just behind, the maneuver element. Many fire missions are conducted using direct-lay, direct-alignment, or hip-shoot techniques. Since exploitations occur deep behind enemy lines, the mortar platoon leader ensures that ammunition is conserved since resupply may be difficult.

e. Pursuit. The pursuit normally follows a successful exploitation. The primary difference is that it is oriented on the final destruction of retreating enemy units. The considerations for rapid movement, security, and resupply are much the same as in the exploitation.

4-4. OTHER OFFENSIVE OPERATIONS

Other offensive operations are limited objective, limited scale, or specially designed operations. They follow the basic considerations for hasty and deliberate attacks.

a. Raid. A raid is normally a platoon- or company-size operation into hostile territory to secure information, to confuse the enemy, to destroy his installations, or to liberate personnel. Company or battalion mortars can be attached or placed under OPCON. If the raid force is dismounted or moved by helicopter, mortarmen carry the mortars and ammunition. The commander can direct riflemen to carry one or two mortar rounds each.

b. Reconnaissance in Force. A reconnaissance in force is a limited objective attack by a strong force to obtain information; to discover or test the enemy's dispositions, strengths, weakness; and to force a reaction by his reserves or fire support elements. The commander ordering the mission must be prepared to extricate the force or to exploit its success.

(1) To the mortar platoon leader, a reconnaissance in force is conducted the same as a deliberate attack. Fire planning is detailed to increase responsiveness. The mortar platoon leader can adjust rapidly to changing situations that may include supporting the withdrawal of the force, a hasty defense, or an exploitation.

(2) Depending on the distance to be covered, mortars can be the maneuver commander's only means of indirect fire support. As such, platoon leaders position mortars to provide continuous fire support throughout the operation.

(3) The sections or squads cover greater distances between displacements and should be prepared to engage targets using emergency techniques.

4-5. MORTAR OFFENSIVE FIRE SUPPORT

Commanders plan mortar fires on the terrain to be traversed and on the flanks to protect the force. If friendly forces make unexpected contact, immediate suppression missions may be fired. Mortar sections establish firing positions within forward assembly areas to protect against enemy spoiling attacks. Mortar fires are always planned from these assembly areas, though they may not be registered or prefired.

a. Fires en route to the objective can be divided into the following phases:

(1) Short of the LD/LC.

(a) Plan fires on checkpoints, passage points, release points, and attack positions to support movement to the LD/LC.

(b) Plan targets to support in the event the enemy conducts a spoiling attack.

(2) From the LD/LC to the final coordination line (FCL).

(a) Fire smoke and HE to obscure obstacle breaching operations and to suppress enemy fires.

(b) Target mortar fires on friendly rally points, objective rally points, and assault positions to allow ease of adjustment from these known locations.

(3) From the FCL to the limit of advance.

(a) Plan suppressive fires on the rear of enemy locations and along likely avenues of withdrawal.

(b) Plan smoke and HE fires on likely enemy reserve positions and assembly areas.

(c) Plan defensive fires on likely enemy counterattack routes and support positions.

b. Preparatory fire is an intense volume of fire delivered in accordance with a time schedule to support an attack. It is normally divided into three phases. Fires may start at a prescribed time or be held on call until needed. The length of the preparation depends on ammunition levels (CSR) and the number of targets for attack. Mortars may not always have adequate range to fire at targets in all three phases. Therefore, the weapons are scheduled into the phase that is within their capabilities rather than being excluded from the preparation. Commanders plan fires on the basis of the sustained rate of fire for each weapons system.

(1) Phase I provides for the early attack of enemy indirect fire support assets and observation capabilities. These targets are the slowest to recover. This degrades the enemy's ability to react with indirect fires and to gain intelligence about the friendly force. The battalion mortar platoon may play a major role in this phase of the preparatory fires. The brigade commander may have the FSCOORD position and mass the fires of the brigade's heavy mortars against enemy mortar units or reconnaissance elements. Mortars may contribute to the counterfire program to free artillery and to aid in J-SEAD programs.

(2) Phase II concentrates on identified CPs, communications positions, assembly areas, and reserves. The goal is degradation of the enemy's ability to reinforce his defense and to shift forces to counter the main attack. Mortar targets are based on weapons capabilities.

(3) Phase III concentrates on the forward portions of the enemy defensive area and targets that pose an immediate threat to attacking troops. The purpose of this phase is to suppress and obscure enemy direct fire systems until the assault force has closed with them. Mortar fires are most likely used during this phase, especially against enemy reverse-slope positions, which can only be reached by high-angle fire.

c. Fires on-call are preplanned targets fired on request not influenced by time schedules. On-call targets are planned to isolate all or part of the objective, to provide illumination during night attack if needed, and to disrupt an enemy counterattack.

d. Fires in support of consolidation and reorganization are planned to protect friendly units against enemy counterattack or reinforcement. Mortar fires on likely enemy withdrawal routes disrupt his organized retrograde operations.

4-6. OTHER OPERATIONS

Other types of operations include passage of lines, linkup, breakout from encirclement, and relief in place. They may occur during either offensive or defensive combat.

a. Passage of Lines. This occurs when one unit passes through the positions of another, as when elements of a covering force withdraw through MBA. A passage can be designated as a forward or rearward passage of lines. It can be conducted in offensive, defensive, or retrograde operations.

(1) Detailed reconnaissance and coordination ensure that the mortar platoon conducts the passage quickly and smoothly. Personnel can be overly concentrated, fires of the stationary unit can be masked temporarily, and the mortar platoon may not be able to react to enemy action. Direct and indirect fires of the stationary unit are normally integrated into the fire support plan of the passing unit. Mortars and FIST can be collocated to provide coordinated and responsive support. Often mortars from the stationary unit provide fire support to the moving unit out to the limit of range. Particular attention is given to restrictive fire measures used to control these fires. The use of fire direction nets is also coordinated. The mortar platoon usually operates within the stationary platoon's fire direction nets. Call signs are exchanged and FDC personnel are informed that calls for fire can be received from the passing unit.

(2) The passing unit's mortars conduct a rearward passage of lines using appropriate displacement techniques until the maneuver element is within range of the stationary mortar platoon. The mortars can then move to and through the passage point either as a platoon or in sections.

(3) A mortar platoon normally conducts a forward passage when the maneuver element is just short of the stationary mortar platoon's maximum range. The passing mortars then begin displacement techniques to support their maneuver element with continuous fire.

b. Linkup. This is a meeting of friendly ground forces. Examples of a linkup include: when an advancing force reaches an objective previously seized by an airborne or airmobile force, when an encircled unit breaks out to rejoin friendly forces, or when converging maneuver forces meet.

(1) A linkup requires detailed restricted fire line (RFL), close coordination and detailed planning of movement, fires, control measures, and recognition signals. Ideally, an exchange of liaison officers takes place before the operation. Depending on the mission after the linkup, either force can be attached to the other or both can remain under control of the directing headquarters.

(2) To the mortar platoon leader, a linkup is conducted as a movement to contact if supporting a converging force or as a defense if supporting a stationary force. In either case, he ensures that all restrictive fire control measures are followed as the two forces converge.

c. Breakout From Encirclement. This is an offensive operation conducted by an encircled force. A breakout normally consists of an attack (penetration) by a rupture force to open a gap through enemy forces.

(1) Before a breakout attempt, all fire support assets are organized under centralized control, and fire support coordination is integrated into the breakout plan. Mortars in this situation may find themselves supporting the defense of the encircled perimeter and supporting either the diversionary or rupture attack. The ability to mass fires when needed may be critical to the success of the breakout attempt. Mortars have to remain flexible since they may be called on to provide deceptive and concentrated fires at the same time to aid in the penetration.

(2) Mortar platoons must exercise proper fire control to avoid depleting ammunition stores since resupply may be impossible.

d. Relief in Place. This is an operation in which a unit is replaced in combat by another unit. The incoming unit assumes responsibility for the combat mission and the assigned sector or zone of action of the replaced unit.

(1) Mortar sections and their FOs are relieved after the maneuver companies. The mortar platoon remains in position, ready to fire, until the relief is nearly completed. The mortar element being relieved passes on its range cards, target lists, and overlays to the incoming mortar platoon to ensure effective delivery of fires. Machine gun tripods and mortar base plates (if ground mounted), aiming posts, telephones, and wire lines can be left in place and exchanged. Authority to do so would be included in the relief order of the next higher commander. This simplifies the effort and lessens the time required to effect the relief.

(2) To ease occupation of the positions during hours of limited visibility, the incoming platoon leader conducts a reconnaissance during both daylight and darkness.



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