The important considerations of defense are combined in utilization of terrain and coordination of fire. The natural defensive characteristics of the terrain should be improved, and camouflage should be used freely. A fully coordinated use of all available weapons must be arranged; strength should be conserved by keeping the losses in personnel and matériel down to the very minimum; and exact dispositions, strength, and intentions should be denied to the enemy as long as possible. A well-organized defense capable of quickly and effectively reverting to the attack, with cunning and deception enshrouding the movements and dispositions, will offset hostile numerical superiority.
60. FAVORABLE TERRAIN FOR DEFENSE
The defender has an advantage in that he selects the terrain for his battle. Rarely will all of the following terrain requirements for defense exist in a single combat area, but certain of them will be present, and the commander may improvise the others: (a) good observation for artillery and other supporting weapons; (b) protection against hostile observation; (c) natural obstacles against tank attacks; (d) natural protection for flanks; (e) possibility for launching counterattacks.
61. OTHER CONSIDERATIONS
a. Defense or Delaying Action?
The mission must clearly indicate the form of defense contemplated: defense (Verteidigung), meaning that the position will be held under all circumstances; or delaying action (Hinhaltender Widerstand). Fire may be opened either at maximum effective ranges, if the ammunition is ample, or at closer ranges, in order to effect surprise.
b. Preparation of Defense Area
When the hostile situation has not been clarified (especially if the direction of the enemy's attack is unknown), the mass of the defending force should be retained in a position of readiness. When information relative to hostile formations, main effort, strength, etc., becomes, available, then the troops may be moved into defensive positions which have been previously reconnoitered and prepared according to the time available and the situation. Occasionally only a skeleton position will be occupied with artillery protected by small units of infantry, while the mass is held back centrally located so that it can quickly occupy positions upon the approach of the enemy.
Advanced positions and outposts delay him and give time for the occupation and preparation of favorable defense terrain. Reserves are used for flank protection, for counterattacks, and for blocking penetrations. Fire power must never be weakened by holding out unnecessarily large reserves. If, after contact with the enemy, the situation requires defensive maneuver, the position is quickly organized as the troops deploy, and if the terrain is not particularly favorable, the troops are drawn back to better defensive terrain.
62. GENERAL PRINCIPLES OF DEFENSE
Some of the general principles of defense can be summarized as follows: (a) The purpose of the defense is to nullify the hostile attack. (b) The position selected is held to the last; the commander may under certain circumstances, however, restrict the time. (c) The defensive position selected must compel the enemy either to attack, relinquish the advance, or attempt to avoid combat.28 (d) Hostile envelopments are countered by extending or refusing the flank (or flanks), or by echelonment of reserves. (e) If the enemy attempts to march around in order to avoid the position entirely, then he should be attacked.
63. ORGANIZATION OF DEFENSE AREAS
a. Defense in Depth
The main battle position is organized in depth to accomplish dense all-around fires and effectively limit hostile penetrations. Local withdrawals before superior hostile fire may be authorized by the regimental commander to his battalion commanders, or, in special cases, by the latter to their subordinates; local withdrawals must not, however, permit the loss of connection between units in the line or hostile penetration into the main battle zone. In terrain not too unfavorable for the defense, units occupy fronts double the width of those assigned for the attack. These islands of resistance are so organized as to permit all-around defense, with weapons so sighted as to cover all possible avenues of approach at maximum ranges.
The defensive zone is organized in depth, with the main line of resistance in front of the terrain that is favorable for observation posts for the artillery and heavy supporting weapons. The higher commander selects the general defensive line on the map and assigns sectors to units. Subordinate commanders carefully reconnoiter the terrain and select the locations for their troops and various types of weapons.
b. Cover and Obstacles
Cover for machine-gun emplacements, observation posts, and accompanying weapons is provided. Obstacles are constructed to supplement the natural defensive characteristics of the terrain. Priorities of defensive works are governed by the rule that "effectiveness of fire takes priority over cover." The normal order of tasks is the following:29 (a) clearing fields of fire and establishing distances to increase the efficiency of fire; (b) camouflaging installations and erecting dummy establishments; (c) constructing splinter cover for observation posts; (d) constructing machine-gun emplacements; (e) erecting barbed wire or other obstacles; (f) excavating dug-outs, switch positions, or planned communication routes.
64. RESERVES, RELIEFS, AND REAR POSITIONS
Local reserves are used to fill in gaps in the line, to counterattack against a local penetration, and to relieve troops in the front line. General reserves are used to protect a flank, to counterattack against a serious penetration, to counterattack when the situation indicates a return to offensive tactics, and to relieve organizations in the line.
A relief is only effected after a long period of defense, and under cover of darkness. Infantry and artillery are never relieved simultaneously. The relief order directs when and where the relief is to report, the routes to be used by the relieving force and the troops relieved; and the time when the new commander is definitely to assume responsibility for the sector.
Only necessary under exceptional circumstances, rear positions must be located sufficiently back from the main line of resistance to require the enemy artillery to move forward. A rear position will be ordered occupied by the commander when the former position can be held only with unjustifiable losses and when consideration for adjacent units does not forbid.
65. ACTUAL OPERATION OF THE DEFENSE
a. Main Line of Resistance
All fires along the main line of resistance and in the principal defensive zone are carefully coordinated to insure that all areas, particularly the potential avenues of approach, are covered by strong concentrations. Artillery and infantry are coordinated to permit a rapid switch from one area to another; and fire plans are prepared to limit penetrations and to block envelopments.
Defensive preparations are secured from hostile observation by active reconnaissance and by a screening force, both of which operate under the same commander. Generous use of obstacles. natural and constructed, is made. The advanced troops are under direct control of the commander; after fighting in delaying action before superior enemy forces, they withdraw to rearward positions as prearranged by him.
b. Advance Position
The advance position, usually located within the sphere of operation of friendly long-range artillery in the main battle position, is occupied to prevent the early seizure of important terrain features by the enemy. Camouflage and dummy works are used freely. The advance position increases the effectiveness and the time of employment of long-range artillery by protecting advanced, artillery observation posts; also, such a position deceives the enemy relative to the dispositions and organization for defense, and causes him to deploy prematurely. Friendly troops must withdraw before the enemy can overrun the position. In withdrawing, prearranged routes will be indicated to insure that the fire of weapons located in the next position to the rear (outpost line of resistance) is not masked.
c. Outpost Position
The outpost position, located within the sphere of operation of the light artillery batteries in the main position, is selected to provide time for troops manning the main defensive position to prepare for action, to supplement observation, and to deceive the attacker relative to dispositions. Troops from infantry units immediately to the rear generally occupy this line and are withdrawn by signal according to prearranged plan so that fields before the main line of resistance are not obstructed. Artillery delays the hostile approach by the use of harassing fires controlled by radio reports from advanced observation posts. To increase radius of action, a few light batteries may be advanced forward to locations between the outpost line and the advance position.
66. ARTILLERY IN THE DEFENSE
a: Control by Artillery Commander
The commander of the whole defensive force determines the proportion of artillery to be held in direct support and the proportion to be attached to infantry units. Artillery is kept as far as possible under the control of the artillery commander, who under all circumstances retains control of the mass of the division artillery. If the situation permits and there is an ample ammunition supply, heavy fires may be delivered at long ranges.
In the initial stages of a defensive action, artillery may sometimes be kept silent to facilitate deception; otherwise, it will be employed to draw hostile artillery fire, to deliver counterbattery fires, or to bring down harassing fires on the approaching hostile infantry. In the advanced stages of a defensive action, the bulk of the artillery is used to deliver concentrations on hostile positions of readiness, and particularly on hostile heavy infantry weapons; the remainder is used to deliver counterbattery fire. And in the final stage--when the hostile force is on the point of launching its assault--the artillery delivers preparations and barrages upon the hostile assault.
Should the enemy make a surprise attack at night or in a fog, a barrage of all weapons is delivered immediately in front of the main line of resistance. Definite restrictions relative to coverage and duration of fire are issued.30 As a rule, heavy artillery does not participate.
67. INFANTRY IN THE DEFENSE
With part of their heavy weapons, the infantry opens fire upon the approaching enemy at good distance; if friendly artillery support is weak, at maximum ranges. Firing positions are located in advance of the main line of resistance or in the forward part of the defensive area. As the enemy draws closer, he is engaged by the fire of all the defending heavy weapons, and finally by the fire of all available weapons. The infantry fills up gaps in the line, recapturing any sections temporarily lost.
68. HOSTILE PENETRATIONS
Where small groups of the enemy have broken through, the groups should be destroyed immediately. Box barrages placed in their rear will preclude their withdrawal. When a successful break-through of large proportions has been accomplished by the enemy, the commander of the defensive force will decide whether the position will be shifted or the lost ground regained by counterattack. If he decides to counterattack, the fires of all weapons are carefully coordinated, a limited objective is assigned, and air and tank support is provided.
69. THE COUNTERATTACK
It is most important that the psychological moment be recognized for the counterblow. The commander is ever alert for indications.31. The counterattack plan resembles a limited-objective attack in which artillery support, boundaries, and objectives are specified. Any objective selected must be a decisive terrain feature.
70. WITHDRAWAL TO A REARWARD POSITION
Advance orders are issued to effect a withdrawal, thus ensuring coordination. Contact with adjacent units is maintained. The movement to the rear is effected under cover of darkness.32 Activity on the original position will be simulated to deceive the enemy. Firing by part of the infantry and artillery will be continued from the forward position to give the enemy the impression that it is still being strongly defended. The hostile advance upon the new (renewed) position will be delayed by the fire of artillery and heavy weapons, supplemented by means of poison gas and obstacles.
29 Several of these tasks, such as camouflaging, may be undertaken concurrently with other tasks.
30 In this connection a light howitzer battery
31 Hostile repulses, heavy losses, enemy errors, morale of the enemy, or morale of friendly troops.
32 Daylight withdrawals are only attempted under cover of fog, artificial or natural, or over terrain of very restricted visibility, when the situation definitely indicates that it will be dangerous to wait until darkness.