• 192. TANK DESTROYER GROUP.—a. The tank destroyer group is a force of variable composition, organized for mass action against large armored units. It consists primarily of—

(1) A headquarters capable of maneuvering and administering a force of all arms.

(2) Several (usually three) tank destroyer battalions.

(3) Other attached troops in accordance with the situation.

b. These attached troops may include ground and air reconnaissance elements, tanks, mechanized cavalry, motorized infantry, engineers, and chemical warfare units. The tank destroyer group is preferably engaged in concert with other troops but is capable of independent action against a large armored unit.

• 193. FUNCTIONS OF COMPONENTS.—a. Tank destroyer battalions constitute the major combat element of the group.

b. Observation aviation and the warning service furnish information of the approach of hostile armored units.

c. Attached mechanized cavalry furnishes distant ground reconnaissance and provides a major contribution to the warning service of the group. It gains and maintains contact with hostile armored units and furnishes information of their activities and those of friendly troops engaged against the enemy, as well as information of the terrain.

d. Attached motorized infantry constitutes the group's principal means of action against hostile foot troops. It protects tank destroyer units against infantry attack. By defeating foot troops protecting hostile tanks in bivouacs or assembly areas, it allows destroyers to engage the latter. When hostile infantry is in superior strength, it maintains contact and forces the enemy to commit his tanks to action or to be constrained to move only at the rate of foot troops.

e. Tanks provide the group with means of clearing up vague situations rapidly, and for prompt offensive action against small forces of hostile foot troops. Tanks assist in the rapid penetration of screens providing security for hostile tank assemblies. During combat against armored forces, they constitute a mobile reserve.

f. Attached antiaircraft elements are used on the march and in bivouac to protect the group command post and units which contain few or no organic antiaircraft weapons. In combat they protect vital areas against hostile air attack, and as a secondary mission engage hostile tanks.

g. Attached engineers lay mines and obstruct routes so as to canalize or impede the movements of hostile armored forces, and assist the rapid movement of the tank destroyer group.

h. Attached chemical troops screen the movements of destroyers with smoke, cover withdrawals by blinding hostile observation, and assist in canalizing hostile movements.

• 194. ALLOTMENT AND CONTROL.—a. Tank destroyer groups are usually allotted to army corps and field armies as indicated in paragraph 36.

b. In most instances groups will operate under an army corps. They may be attached to divisions when the armored engagement is taking place entirely in a divisional zone or sector, or when the division has an independent or semi- independent mission.

c. The army commander usually will attach the groups assigned to him to the army corps as the situation develops. However, groups operating in an area not occupied by a corps, such as an area to a flank or deep in the army area, usually will remain under control of the army commander.

• 195. GENERAL.—Tank destroyer groups are intended for action against massed tank forces. As part of the mobile reserve of the high command, they are initially so disposed as to facilitate their rapid entry into action against large armored forces.

a. Tank destroyer groups which are attached to units engaged in offensive combat assist the attack by furnishing protection against large scale counterattacks by hostile tanks. They follow the attack closely, moving by bounds from one position in readiness to another. In enveloping attacks, they are usually echeloned toward the interior behind the enveloping flank.

b. Tank destroyer groups attached to units whose action is defensive are usually held in mobile reserve until the enemy's main effort is indicated and then engaged in mass against the hostile armored force. Depending on the situation, this may be prior to or after the launching of the hostile armored attack.

c. With a view to disrupting the enemy's plans and dispositions and seizing the initiative from his armored forces, tank destroyer groups may be directed, under favorable circumstances, to attack hostile tank concentrations before they have completed their preparations for battle. The support of artillery and combat aviation and the assistance of infantry and tanks will usually be required to break through the enemy's protective screen and allow tank destroyers to assail their objective. The higher commander directing the action may constitute a task force for this purpose.

d. More often, lack of the necessary means of action or of the necessary information will lead the defending commander to hold the tank destroyer group for employment as a counter- attacking element. Tanks which have effected, or partially effected, a break-through constitute an ideal objective for tank destroyer groups, since the tanks will frequently have outstripped their accompanying infantry and supporting weapons.

• 196. OCCUPATION OF PARK—a. The park of the tank destroyer group must be located so as to facilitate expeditious movements to any part of the zone of action of supported troops; usually it will be in the general vicinity of important road crossings. The high degree of mobility of tank destroyer units permits the establishment of bivouacs well to the rear, providing that access to forward areas is not impeded by congested highways or other obstructions, such as defiles, etc. Hostile aircraft, operating in conjunction with tank forces, are likely to make tank destroyer groups a primary objective; parks usually, therefore, will be selected more with regard to protection from air attack than from ground attack.

b. The group commander insures that the tank destroyer force is effectively tied into the warning net of supported troops and that destroyer units are disposed so that they can move out of bivouac to a zone of action in the shortest possible time. The group will normally be located in an area approximately 5 miles square or smaller. Subordinate elements are located so as to get the best cover and at the same time be conveniently located with respect to routes on which movement is most probable. Separation of subordinate elements by more than 1 or 2 miles is undesirable and usually unnecessary. Arrangement of subordinate elements is such as to facilitate contemplated employment. Main roads leading into the area from all directions are covered by security detachments posted 2 or 3 miles from the group's bivouac.

c. The group commander prescribes the degree of readiness for action to be maintained; this is progressively increased with the prospect of early engagement.

d. The group commander causes routes and probable areas of employment to be reconnoitered by officers. In some cases plans of action, including order of march and areas of deployment, are prepared. Reconnaissance is also executed to carry out intelligence missions assigned by higher authority or to obtain information required by the group. The group commander employs for this purpose group headquarters company personnel or mechanized cavalry, when available; if these do not suffice, he allots missions among tank destroyer battalions which utilize elements of their reconnaissance companies for this purpose.

e. The group commander insures that all available information of the situation is transmitted to his subordinate units.

• 197. MARCH.—a. Tank destroyers require priority on roads when moving to combat. The group commander must insure that the way will be clear for tank destroyers when need for their intervention arises. Close coordination of tank destroyer group units with the movement of supported troops is essential.

b. The group commander prescribes the route, march formation, rate of march, and distance between vehicles: these depend on the situation. The proximity of the enemy is the factor which exercises the greatest influence upon march dispositions; these likewise are affected by the probability of hostile air attack and the protection afforded by covering troops. The probability of attack by hostile combat aviation increases with proximity to the enemy, visibility, duration of the movement, the size and compactness of the group, and the utilization of main roads. Observation of a movement by hostile observation aviation usually precedes an attack. Routes will be observed particularly closely when strong forces are approaching one another. Danger is greatest when the situation requires the group to make a daylight march of considerable duration along well-defined roads to meet a hostile armored force. The latter almost invariably will be supported by strong forces of combat aviation. Movements in rear areas which can be completed in less than 3 hours have excellent chances of escaping attack. Small portions of the group effecting isolated movements at night in the rear area will seldom be molested. Columns moving with variable and extended distances between vehicles (5 to 10 to the mile) and at the highest practicable speed are relatively difficult to detect by hostile observation aviation and will not provide profitable targets to combat aviation. Necessary daylight movements are preferably made in this manner if the situation permits; the necessity, however, of passing a large number of troops over a road in a short period of time will often preclude use of such methods by the group.

c. The tank destroyer group preferably moves in more than one column. The number of columns will depend upon the situation and the road net. Formation on the march must correspond to contemplated combat dispositions. When available, mechanized cavalry, motorized infantry, and tanks will usually constitute the leading elements, with destroyer battalions following as a second echelon. One destroyer battalion, earmarked as a reserve, will usually move with rear elements of the group.

d. The group commander provides for the necessary reconnaissance; this is similar in principle to that indicated for the movement of a destroyer battalion. The group employs attached observation aviation and mechanized cavalry to obtain required information or distributes reconnaissance missions among destroyer battalions. Excessive dissipation of reconnaissance elements of tank destroyer battalions should be avoided; necessary employment is characterized by assignment of the major portion of reconnaissance missions to the battalion selected to act initially as group reserve.

e. The group commander prescribes a march objective and may indicate where and when attack orders will be issued. Usually, battalion march objectives are suitable assembly areas; they are assigned with regard to subsequent contemplated employment of battalions (combat echelon or reserve).

f. During the march the group commander is kept informed as to its progress, traffic conditions, and hostile activities by reports from the aviation and ground reconnaissance agencies and by messages from subordinate commanders. He regulates the movement accordingly, prescribing new routes or march objectives when required by the situation.

• 198. ENTRY INTO ACTION.—a. Whenever practicable, the group organizes its combat action while subordinate elements are occupying their assembly areas. Measures may be limited to announcement of the situation, the contemplated plan of action, and instructions to leading elements for reconnaissance and covering of a further advance.

b. The group commander, in accordance with his estimates of the situation, determines appropriate missions for the various components of the group. In particular he decides whether tank destroyer battalions are to constitute the combat echelon initially or whether preliminary action by other elements is required. The group commander insures the proper coordination of the action of his own forces and that of other friendly troops in the vicinity.

c. Orders are based upon data which include information of the enemy, instructions from higher authority, the situation and contemplated action of adjacent units, fire support, and the terrain.

• 199. PLAN OF ACTION.—a. The plan of action of the group commander usually provides for blocking or engaging the enemy frontally in conjunction with a blow at his flanks or rear. As soon as possible the group endeavors to gain control of routes over which the enemy has advanced.

b. Utilizing its ground and air reconnaissance, the group usually advances on a broad front with two tank destroyer battalions abreast and one in reserve. Only one tank destroyer battalion may be used in the combat echelon in vague situations; initial engagement of all tank destroyer battalions will usually be limited to situations in which both flanks of the group are protected by other troops or the situation is such that the full strength of the group must be exerted at once.

c. Tanks and infantry, depending on the situation, precede the tank destroyer battalions or are held in reserve. Mechanized cavalry elements continue their reconnaissance missions and cover the flanks. After the combat echelon has become engaged, the reserve may be maneuvered to assist in the action against the hostile flanks and rear, used to support elements engaged frontally, or continued in reserve until suitable opportunity arises for its employment.

d. When hostile tanks are preceded or covered by foot troops, the group commander decides whether to engage the latter with his attached infantry or to effect a rapid penetration with attached tanks followed by destroyers. Attacking infantry may be supported by direct fire of destroyers using high explosive shell.

• 200. CONDUCT OF ACTION.—The group commander conducts the action from a location where he can best control his battalions, receive information, and wherever practicable personally observe the action. He engages his reserve in accordance with the situation, alters previously assigned missions of subordinate units, or assigns entirely new missions in accordance with developments. By means of his ground and air reconnaissance and reports of engaged units, he keeps informed concerning the situation, and maneuvers his battalions so as to have superior forces in the selected area of contact. He endeavors to hem the enemy into, restricted areas facilitating his destruction. He reconstitutes a reserve at the earliest opportunity after engaging his original reserve. In so doing, he respects the integrity of tactical units so far as is practicable. Control of subordinate elements in combat is normally by voice radio.

• 201. REORGANIZATION—The group commander indicates the time and general area for reorganization and the time at which subordinate elements should be ready for further combat employment. He may indicate a location at which commanders report for further orders.

• 202. WITHDRAWAL.—The group commander assigns routes to subordinate units and indicates the time at which withdrawal is to begin and the ultimate or initial destination, together with contemplated dispositions there. He may detail a covering force. Separate routes are assigned to each battalion whenever practicable.

• 203. PURSUIT.—The group usually pursues on a wide front combining direct pressure and encirclement. The group commander assigns missions to battalions, a portion of which are directed so as to intercept the retreating enemy. Decentralization of control is usual.

• 204. COMPOSITION AND MISSION.—a. Group headquarters and headquarters company is organized as indicated in T/O 18-10-1.

b. The principal mission of headquarters company is to furnish the necessary enlisted assistants for the group commander and his staff and to provide for their immediate security. When the latter mission is unnecessary, security elements of headquarters company may be used for reconnaissance.

c. The various elements of headquarters company perform their functions at or in the vicinity of the group command post or, in case the group includes attached service elements, at the park. (See FM 18-10.)

• 205. COMMAND POST.—a. In park.—In a park or intermediate position the group command post is usually centrally located with respect to subordinate elements. Provision is made to allow approximately a dozen officers and enlisted men to work in the command post by night under adequate lighting, or to assemble officers conveniently by night, for conferences or to receive orders or information.

b. On the march.—On the march the command post usually moves behind the bulk of the combat elements. The command post is advanced to a new location in preparation for combat when its previous location is too far from the area of probable action for effective communication with subordinate units. Movement in such case is usually effected by bounds; a forward echelon is sent forward as early as the situation permits; when it has been established, the remainder of the command post advances: A bound of less than 10 to 15 miles is seldom justified.

c. In combat.—(1) The command post is organized so that the commander, with a party containing adequate means of communication, can go where his presence is necessary best to control the action, while the bulk of the command post continues to function from a stationary location, facilitating communication with higher authority, aviation, and supply services.

(2) The commander's party normally includes S-2 and S-3; it consists of armored vehicles providing radio communication with the command post and with principal subordinate units. The party is protected by a portion of the security section of group headquarters company. Liaison officers of major subordinate elements accompany the commander.

(3) The executive remains at the command post during combat. He supervises administrative arrangements, keeps informed as to the situation, and is prepared to take over promptly in case the commander becomes a casualty. He insures the prompt relaying to the commander of important orders and information.

• 206. LIAISON OFFICERS.—The group maintains liaison officers at the command post of the large unit to which it is allocated, and may send representatives to other units with which it is likely to operate. The liaison officers keep the group informed as to the general situation and plans for employment of the group. Periodical summaries are transmitted by messenger or personal contact, important changes being sent by radio.

• 207. LIAISON WITH SUPPORT AVIATION.—a. The group headquarters maintains close liaison with combat support aviation designated to cooperate with it. Plans and arrangements for missions are effected in advance by conferences. Air forces personnel are provided with maps marked in the coordinate code that is in use in the group. These preliminary conferences insure prompt arrival of combat aviation when need arises, and reach agreement upon methods of target designation and communication. Whenever practicable, support aviation personnel, which is actually to execute tasks in support of tank destroyer units, should participate in the conferences. Information concerning agreements reached should be thoroughly disseminated to subordinate tank destroyer units. Positive means of identifying tank destroyer units and vehicles to support aviation must be provided and must be understood by the appropriate ground and air units.

b. Tank destroyer units must realize that small targets, due to dispersion, camouflage, or concealment, are not stilt- able targets for support aviation.

c. It is essential that tank destroyers indicate to aircraft the location of targets on the ground. Reliance on map coordinates or descriptions alone will not suffice. The following methods may be used:

(1) Firing of specified pyrotechnics by tank destroyers posted in front and on the flanks of the target areas.

(2) Pointing with panels, with range indicated by a proper number of cross bars or discs, each representing a definite distance.

(3) Vehicles in prearranged formation.

(4) Smoke to mark a reference point.

(5) Signal lamps and lights.

d. When practicable, tank destroyer unit observers are posted to note effectiveness of bombing attack and report by radio errors in selection of targets.

e. For details concerning the action of aviation in support of ground forces, see FM 31-35.