99. GENERAL (FM 100-5). Special operations are those in which terrain, weather, or nature of the operation create the need for special measures and techniques.

100. ARTILLERY IN SUPPORT OF RAID. Artillery fires in support of a raid are prearranged and must be closely coordinated with the plan of action of the supported unit. They may include counterbattery, neutralization of hostile reserves, neutralization of known or suspected elements of the position to be raided, interdiction of routes leading to the area, concentrations and barrages to isolate the area, and protective concentrations to cover the withdrawal.

101. ARTILLERY SUPPORT OF NIGHT ATTACK. The artillery completes the necessary survey, establishes liaison, and prearranges fires before dark. Plans must be simple. Fires include counterbattery, fires to deceive the enemy as to location of attack, fires to cover noise made by attacking troops, fires to orient attacking troops, protective fires during the infantry reorganization of the objective, fires to break up enemy counterattacks, and fires to cover a withdrawal. If a preparation is fired, it is usually short and intense.

102. ARTILLERY SUPPORT OF RIVER CROSSING.

a. General. Positions are well forward. Some of the artillery may occupy positions from which it can support both a feint and the main crossing. Secrecy is furthered by the selection of concealed positions, careful planning of march serials, postponing occupation of positions as long as practicable, and limiting or prohibiting registration.

b. Attack of first objective. If the probable effect outweighs the advantage of secrecy, an artillery preparation may be fired; otherwise, all fire is normally held until the leading attack waves have been discovered. Artillery observers and reconnaissance details accompany the leading waves.

c. Attack of second objective. As soon as the leading elements of the supported unit advance from the first objective, the artillery begins displacing across the river. It generally displaces by battery, using ferries. The first artillery units to cross are attached to the supported unit until the bulk of the artillery has crossed.

d. Attack of third objective. The bulk of the artillery should be ready to render continuous support from positions on the enemy side of the river. Centralized control is highly desirable.

103. ARTILLERY IN DEFENSE OF RIVER LINE. A river may be employed as an obstacle in front of a defensive or delaying position, or in conjunction with a defensive-offensive operation.

a. When river line is employed as obstacle. The artillery is employed as in the defense of a position except that usually only a part of the artillery is emplaced initially to cover the most likely crossing places, probable assembly areas, and avenues of approach. The remainder is held in reserve to support the defense when the location of the main crossing is discovered. The enemy will employ every subterfuge to cause the defending artillery to open fire and thus disclose its positions. To defeat these attempts, some units may be directed to open fire only on orders of higher headquarters.

b. When river line is aid to defensive-offensive. In this case, some artillery is attached to the outpost detachments. It is employed as in the support of an outpost of a defensive position. Platoons or batteries are emplaced in concealed positions to cover the probable points of crossing and the approaches to them. These units remain silent until suitable targets present themselves; then they deliver surprise fire. The mass of the artillery is held in reserve, prepared to support the defensive-offensive. The artillery plans usually cover two phases: First, the support of the outpost detachments where a hostile crossing is being made; second, support of the main force in its counteroffensive. In the first phase, the artillery occupies positions from which it can concentrate against the hostile points of crossings, bridges under construction, and hostile approaches to the river. In the second phase, the artillery is employed as in the support of an attack.

104. ARTILLERY OPERATIONS IN SNOW AND EXTREME COLD. Operations in snow and extreme cold are covered in detail in FM 31-15. The measures necessitated by snow and extreme cold are technical rather than tactical. In deep snow it may be necessary to replace trucks with track-laying vehicles and to place runners under wheels. The use of trail-breaking vehicles to pack roads and trails in advance of wheeled or track-laying vehicles is recommended. The value of pack units is seriously impaired when the depth of snow exceeds 20 inches. In extreme cold, special lubricants must be provided for weapons and instruments; recoil oil is warmed before use, unless special recoil oil is provided.

105. ARTILLERY IN MOUNTAIN WARFARE. In forces operating in mountainous terrain it is desirable that a portion of the artillery be pack units for operating off the main route. Other artillery, so far as practicable, should be capable of high-angle fire. Interdiction and fires on enemy assembly areas are particularly effective because the points that the enemy is compelled to pass and the areas in which he will form for attack may be determined usually by a study of the terrain. Observers are echeloned in altitude as well as in width and depth. Control of artillery is generally decentralized.

106. ARTILLERY IN JUNGLE WARFARE. Jungle warfare is covered in FM 31-20. The jungle affects artillery employment by restricting observation, movement, and supply. Light artillery may be transported by air to the general vicinity of position areas. Movement by other means is generally restricted and slow. Methods of transport include motor, pack animal, draft animal, barge, boat, improvised handcart or sled, and manpower. Great reliance is placed in forward observers with the foremost infantry elements. These observers are often required to adjust fires by estimating the location of bursts by sound (by ear, not mechanically). Suitable battalion and battery observation posts are seldom found. Observation from boats offshore may be feasible in coastal regions. Air observation and sound-ranging are sometimes practicable. Communication is relatively restricted and slow. Wire is the principal means of ground communication. Control of artillery is often decentralized. High-angle fire and adjustments close to friendly troops are often necessary.

107. ARTILLERY IN DESERT WARFARE (FM 31-25). The field artillery uses its normal types of fire and fire direction in desert warfare. Fire by direct laying is important. Security against ground attacks is stressed. Dispersion is the primary means of passive defense against air attack and counterbattery. Ground observation is frequently limited to 2,000 yards by undulations in the terrain and by shimmering atmosphere. Air observation, sound ranging, and flash ranging are employed to the maximum.

108. LANDING OPERATIONS (FM 31-5). Landing operations and the attack of coast lines involve joint action by the Army and Navy; they are governed by special regulations.

109. ARTILLERY IN DEFENSE OF COAST LINES (FM 31-10). The bulk of the subsector field artillery must be able to oppose a hostile main attack and to support a counterattack by the subsector reserve. Until the location of the main attack is known, a large part of the artillery is emplaced initially to support the outposts actively engaged; the amount so emplaced depends on the mobility of the artillery and on the road net. The initial positions should be near roads to facilitate prompt displacement. Light artillery supporting the outposts is placed well forward in the probable landing areas to execute fire by direct laying on enemy landing craft, support organized tactical localities along the shore line, and enfilade critical areas of the beach. The remainder of the artillery may be held in reserve or emplaced in depth to support the defensive position.

110. ARTILLERY IN ATTACK OF FORTIFIED LOCALITY.

a. General. Attack of fortified areas is covered in FM 31-50. A fortified position is a defense area which contains numerous steel, concrete, or other permanent defensive works. Depending on its extent and depth, the position may be classified as a fortified locality, a fortified line, or a fortified zone. A fortified locality is a single, strongly organized defensive work; a series of fortified localities disposed in great depth and breadth constitute a fortified zone. A fortified zone may be outposted by a fortified line, or by less highly organized tactical localities.

b. Intelligence. Artillery units exploit fully all intelligence agencies to determine in detail the location of all elements of the hostile position. The production, interpretation, and distribution of air photographs is absolutely essential in order that enemy defensive installations and artillery positions may be plotted on firing charts and neutralized during the preparation and attack.

c. Control. The control of artillery units assigned direct-laying missions is decentralized. Such missions are usually carried out by single weapons attached directly to assault detachments. The bulk of the artillery is held under centralized control in order that massed fire may be employed against enemy artillery, critical areas, and counterattacks.

d. Reduction of outpost. Part of the heavy artillery assists the preliminary operations by constant bombardment of the hostile main position, paying particular attention to hostile artillery which can bring fire to bear upon the troops engaged. The remainder of the artillery furnishes close support to the assault echelons. Supporting fires conform to the movements of the assault units. The heavy calibers place fire on emplacements, massive obstacles, and wire entanglements in the outpost system; flat-trajectory weapons with high muzzle velocity employ direct laying against embrasures. Fires are also placed on flank positions and troop emplacements not being attacked, and particular attention is paid to locating and bringing fire to bear on hostile mechanized elements and local reserves forming for counterattack. A rolling barrage may be employed to support the attack and crater the terrain.

e. Support of break-through. The amount of ammunition and artillery available, the degree of surprise possible, the amount of hostile artillery present, and the depth of the fortifications on the front of the penetration determine the length and intensity of the preparation. Prior to the hour of the attack, the bulk of all supporting fires is concentrated on the front of the initial penetration. Heavy and medium artillery are concentrated on points in the fortifications that offer the greatest danger to the success of the attack; the flat-trajectory weapons are employed against loopholes in the fortifications. Smoke is used extensively. When the preparation is completed, the bulk of the artillery fire is shifted to those areas from which fires can be delivered against the initial assault. Because an enemy in a fortified locality is able to organize and launch counterattacks with unusual rapidity, particular attention is paid to the support of the units extending the flanks of the gap. Once the break-through of the entire locality has been effected, highly mobile artillery is attached to mobile reserves pushed through the gap, while other artillery supports the units that are keeping the gap open.

111. ARTILLERY COMBAT IN TOWNS (FM 100-5).

a. General. Built-up areas, such as towns and villages, offer concealment for troops and weapons and protection from fire and mechanized attack. Since the characteristics of town and village fighting favor the defense, the attacker will usually seek to bypass strongly defended towns rather than make a direct attack.

b. Phases of attack on towns. The attack on a town consists of two phases: First, the capture of an initial position, the possession of which will cut off flat-trajectory fires and limit enemy observation outside the area; second, the advance through the built-up area.

(1) FIRST PHASE. Artillery is used as in the attack of an organized position (ch. 4). Control of the artillery is centralized. The attack is usually preceded by a preparation.

(2) SECOND PHASE. A portion of the artillery may be attached to assaulting units to furnish support by direct laying. Such missions are best performed by tanks, tank destroyers, or infantry cannon weapons. Such weapons should be used if available. The bulk of the artillery should be held under centralized control, available for massed employment against critical areas and against the defender's artillery.

c. Defense of towns. The employment of artillery in the defense of towns is similar to its employment in the defense of an organized position. It is disposed in depth and held under centralized control. Initially, all or part of the artillery may be emplaced well forward to support the outpost. During the attack the massed fire of artillery units should be employed against hostile penetrations and in support of counterattacks.