84. DEFENSIVE COMBAT. See FM 100-5 for discussion of defensive principles.

85. ARTILLERY POSITIONS.

a. Location. Artillery positions are usually in the sector of the supported unit and are echeloned in depth. All light artillery and all medium howitzers must be able to fire immediately in front of the main defensive area. The bulk of the light artillery must be able to place defensive fires and support counterattacks throughout the depth of the defensive position. The positions of forward units are usually selected to facilitate counterbattery, interdiction, and harassing fire. The positions of other units are echeloned in depth to provide flexibility of fire and to permit continuity of support in case artillery in forward positions is forced back by local successes of the enemy. Gun units are given priority in choice of positions. Natural tank obstacles are considered, particularly in the assignment of positions to heavy artillery.

b. Occupation and organization. Positions are occupied with maximum secrecy. In addition to the usual measures taken upon occupying position, lateral circuits are usually laid to provide alternate communication; principal circuits are buried when practicable; and alternate command post locations are prepared.

c. Preparations for units not in position. Preparations for the artillery initially attached to covering forces and for reinforcing artillery coming in later are made by units already in position, or by advance parties from the attached reinforcing units.

d. Alternate and temporary positions. To remain in action in the face of hostile superiority, artillery must exploit its mobility. Alternate positions must be prepared to which batteries move when there are indications that the occupied positions have been discovered. Dummy positions are prepared for deception. Temporary and dummy positions may be used for interdiction and harassing fire in quiet periods, and are habitually used for registration.

86. ARTILLERY SUPPORT OF COVERING FORCES. Strong artillery support is attached to the advanced mobile covering forces; suitable mobile weapons with the longest range should be included. If the general outpost is beyond the effective supporting range of direct-support artillery emplaced in the battle position, artillery from the main force is attached. Upon withdrawal, artillery attached to the advanced covering force or to the outpost is released from attachment when it reaches the main battle position.

87. PHASES OF ARTILLERY FIRES. Artillery fires in support of defensive combat are usually divided into four phases:

a. Fires delivered before the enemy forms for attack.

b. The counterpreparation.

c. Fires to break up the attack after it is launched, final defensive fires, and fires to continue neutralization of the attacking force.

d. Fires to support counterattacks.

88. FIRES DELIVERED BEFORE ENEMY FORMS FOR ATTACK.

a. Time of opening fire. Time of opening fire is decided by the force commander, except for artillery units supporting the outpost. Premature firing exposes the artillery to neutralization and may reveal the scheme of defense of the force. In general, the bulk of the artillery remains silent until dangerous or highly remunerative targets are discovered.

b. Positions. Units required to fire prior to counterpreparation should do so from positions other than those from which they are to deliver counterpreparation fires.

c. Registration. Registration is highly important (see par. 80).

89. COUNTERPREPARATION.

a. Definition. A counterpreparation is a system of intensive prearranged fire delivered when the imminence of the enemy attack is discovered. It is designed to break up enemy attack formations; disorganize the enemy's systems of command, communication, and observation; decrease the effectiveness of his artillery preparation; and impair his offensive spirit. Counterpreparations may be general or local.

(1) General counterpreparation is planned to meet a general attack. It involves the entire front; all of the artillery participates. Since the enemy may launch his main attack from any of several areas, planning more than one general counterpreparation may be necessary; in this case each is given a specific designation.

(2) Local counterpreparation involves only that part of the front that is threatened by a local attack. In the army (corps) the term "local" applies to a counterpreparation fired by one or more, but not by all, of the front-line corps (divisions) ; a division is the smallest unit to execute a counterpreparation.

b. Authority to fire counterpreparation. The attacker may be expected to use every artifice to induce the defender to fire his counterpreparation prematurely. Such premature firing furnishes the enemy with counterbattery data for his artillery preparation, indicates to the enemy what areas are to be avoided in forming for the attack, and expends ammunition that may not be replaceable. On the other hand, the counterpreparation must be fired in time to meet the attack. The order to fire a counterpreparation requires a command decision; the military intelligence upon which the decision is based must be reliable and prompt.

c. Missions in counterpreparation.

(1) GENERAL. Essential to the success of the counterpreparation are counterbattery, the disruption of the enemy's systems of command and communication, and the neutralization of tank assemblies.

(2) MISSIONS OF ECHELONS. In general, the counterpreparation missions of the various echelons are—

(a) Corps artillery. Counterbattery; reinforcing the fires of the division artillery.

(b) Division artillery. Neutralization of known or suspected routes and assembly positions of troops forming for the attack; enemy systems of communication, observation, and command; hostile forward elements; known or suspected assemblies of tanks and reserves. Division medium howitzers may reinforce the corps artillery counterbattery.

90. FIRES TO BREAK UP ATTACK AFTER IT IS LAUNCHED. Should the enemy succeed in launching his attack, the artillery delivers intensive massed fires against the main attack. It keeps the enemy under fire by defensive concentrations on his attack echelons and reserves. Counterbattery is continued. Profitable targets of opportunity are attacked; special attention is paid to enemy mechanized elements. As the enemy approaches the forward defense areas of the supported unit, normal barrages and other final defensive concentrations are fired on call. Should the enemy succeed in penetrating the position, concentrations are fired to disorganize his forces and stop their progress.

91. FIRES IN SUPPORT OF COUNTERATTACKS. Concentrations in support of local counterattacks are prearranged to the greatest extent practicable. A general counterattack is given maximum artillery support, which usually includes an artillery preparation. Secrecy is paramount.

92. COORDINATION OF ARTILLERY FIRES. Fires are prearranged to the maximum and are coordinated both laterally and in depth throughout the defensive sector. Except for initial attachments to covering forces, the artillery is held under centralized control in the defense, so that fires can be massed on critical areas at critical times.

93. ARTILLERY SUPPORT OF REAR POSITION. In preparing the defense, the force commander may designate a rear position to which the force will move in case a withdrawal becomes necessary. The rear position is at such distance from the battle position that the enemy must regroup his forces and displace his artillery before resuming the attack. When a rear position is designated, the artillery reconnoiters and prepares positions and observation.