M 50 Onhos tactics

From: Landing Force Bulletin #23 Employment of the Antitank Battalion (LFB23) USMC 1959

Typed in by 1JMA member WWT





a. The employment of Ontos is influenced by its capabilities and limitations. Employment is primarily defensive in nature.

b. The mobility of Ontos permits it to engage enemy armor forward of the main battle position and, subsequently, to move rapidly from position to position.

c. The firepower of the Ontos enables it to engage successfully any known armored vehicle.

d. The vulnerability of the Ontos and requirement for exposure of the loader favor targets being engaged from well concealed, covered positions. Preselected alternate positions, accessible over covered and concealed routes should be available. When an Ontos fires, it must be ready to execute a rapid displacement to new firing positions. Alternate positions, previously prepared and supplied, afford the Ontos an excellent opportunity to rearm and refuel from pre-positioned supplies.

e. Thorough reconnaissance is one of the most important factors in employment.

f. When practicable, Ontos should be employed by sections in order to provide mutual support.

g. The employment of the Ontos should be integrated with other anti-mechanized means such as tanks, antitank barriers, naval gunfire support, air, and artillery, as well as with the organic antitank means of infantry elements.


a. Purpose. The success of antitank tactics depends largely on preparation for action. Time permitting, extensive and detailed reconnaissance, including reconnaissance by air, is carried out by the antitank battalion, company, and platoon commanders.

b. Actions during reconnaissance.

(1) The AT commander studies and evaluates the ground, noting possible avenues of hostile mechanized approach and potential firing positions. Bridges are noted; fords are selected, if possible, to be used in the event bridges are demolished later. He contacts friendly troops adjacent to, or within, the area to learn their disposition and plans coordinate fires, and to exploit terrain.

(2) Time and other conditions permitting, the commander reconnoiters the ground over which enemy tanks might advance, looking for possible tank and infantry approach routes and studying the area from the enemy point of view.

(3) Sites suitable for friendly observation are sought.


Reconnaissance results in the selection of primary, supplementary, and alternate positions.
a. Positions should be chosen prior to contemplated action so that they may be properly prepared.

b. Unit positions should provide defense laterally and in depth along all possible avenues of armored approach.

c. Positions are established to provide mutual support. This need for mutual support can be met on many occasions by echeloning vehicles in depth. Depth of position and mutual support are particularly important during displacement to alternate positions when it is essential that one vehicle cover another.

d. Individual vehicle and unit positions must afford maximum cover and concealment. A properly covered and concealed unit can, through timely attack by fire, kill, disable, and disorganize the attackers. This ambush tactic may create unacceptable losses or a shock effect, which may cause enemy forces to withdraw, or may contain the enemy and make them vulnerable to attack by friendly forces before their own attack is launched.

e. The effects of cover and concealment are greatly enhanced when positions afford the opportunity of flanking fire. Tanks are vulnerable—and present a larger---target when attacked from the side. Their frontal armor is strong while the side armor and exposed suspension system are weaker and more vulnerable. Concealed flanking guns are also difficult to locate and maneuver against.

f. The position should afford a backblast area free of troops and obstructions.

g. As in the selection of positions for any weapons, consideration must be given to fields of fire and observation.
h. In a defensive situation, consideration is given to the overall organization of the terrain and plan for supporting fires when selecting positions. Positions selected for Ontos emplacement must complement the plan for supporting fires and reinforce natural and man-made obstacles


Since tanks may attack in mass, it is necessary that they be met with massed fires. Accordingly, Ontos should be employed in a manner which will permit the weight of the defensive effort to be placed in the path of the approaching attacks. This ability to achieve mass is influenced largely by the quality and timeliness of intelligence upon which a decision can be made to move sufficient Ontos units to positions of advantage.


a. Local security

Battalion or company sized AT units are capable of maintaining their own local security. However individual Ontos crews are incapable of providing the required degree of local security against infiltrating enemy infantry. Other units in the area should assist in maintaining local security. Assistance is critical when AT units occupy positions on the flanks or forward of the advancing troops or forward of the battle position of defending troops when they are in a defensive position. When so deployed, extensive illumination and preplanned protective fires may be required.

b. General security measures

An AT unit must exercise the same security measures, such as camouflage, use of obstacles, and observation of hostile ground and air attack, as other tactical units. Ontos must at all times be prepared to take evasive action and passive defense measures if attacked by air.

c. Protection against nuclear weapons

An Ontos provides some protection to its crew against the effects of a nuclear explosion. The Ontos is a relatively hard target, but it may be dismantled, thrown, or rolled along the ground by severe blast effects from a nuclear explosion. There should be no loose material or equipment in the vehicle which might fly around and cause injuries. Buttoned up, the Ontos gives protection against thermal radiation. However, combustible material should be removed from the outside of the vehicle to prevent external fires. The Ontos also affords a small degree of protection against prompt nuclear radiation.


The probability of achieving a first round hit is slightly greater when firing a two-round salvo as compared to firing a single round. This gain in first round hit probability must be considered against rapid expenditure of loaded rounds and the more frequent requirement for reloading. Salvo firing of more than two rounds will not materially increase the hit probability. In two-round firing, the order set forth in subparagraph 301a(2) is recommended to maintain turret balance. As a general rule, single round firing is used against stationary targets. Two-round salvos are desirable at the longer ranges against moving targets.


a. The disparity between the armor and armament of a tank and that of an Ontos is an important factor influencing Ontos tactics in attacking armor. This factor emphasizes the importance of taking maximum advantage of cover, concealment, alternate firing positions, and the elements of surprise and mass. Exchange of fire with tanks from exposed positions should be avoided when practicable.

b. Ontos distribute their fire among the attacking tank units, destroying or immobilizing as many as possible. The primary objective is to stop a large number of tanks, not to demolish a few. Once stopped, tanks can be dealt with at any time by a wide choice of weapons. Ontos are positioned and employed to stop tanks as far forward of friendly positions as possible.

c. Immobilization of a tank is usually easier to accomplish than total destruction. Total destruction frequently depends on penetration of heavy armor while immobilization can be achieved by attacking the highly vulnerable suspension system.


When engaging point targets such as bunkers and pillboxes, Ontos should fire from concealed, hull-defiladed positions when possible. The Ontos should not accompany the infantry in closing with the enemy. It delivers supporting fires on vital targets from positions to the rear or flanks of the infantry.



During offensive operations Ontos are employed primarily as antitank weapons. However, other capabilities of the weapon may be exploited.

a. Antitank missions

Attacking infantry are followed by antitank units prepared to counter enemy armored attacks. Routes of advance and firing positions are selected prior to the attack and are reconnoitered and occupied as soon as possible after they are uncovered by the infantry.

1) Positions should by improved and camouflaged immediately upon being occupied.
2) Every effort is made to obtain flanking fire, provide depth to antitank defenses and facilitate mutual support.
3) Selection and occupation of these defenses is carefully coordinated with the infantry to provide mutual support, local security, and ensure optimum defense.

b. Fire support

The Ontos can be used in the assault gun role and is capable of rendering fire support against pillboxes and bunkers. When Ontos are so employed, maximum advantage should be taken of concealment, hull defilade, and alternate positions. Concurrently, Ontos must be available, as necessary, for the antitank mission. If enemy armor appears while Ontos are engaged in fire support, they are released immediately for their primary mission.


When employed in support of defensive operations, the antitank units are disposed in width and depth, Positions extend from locations well forward to those in the rear. From these positions Ontos may move into any area to oppose enemy armor.

a. Position defense

1) Security forces

When the enemy possesses armor, and the situation permits, antitank units are assigned to the security forces. Ontos employed from ambush can effectively delay enemy armor and assist the disengagement of other security forces. Antitank units supplement the tanks in the antitank role.

2) Battle position

Positions cover avenues of tank approach into, and within, the battle position. Some antitank units may be initially assigned forward positions, while the bulk of the units are held to the flanks and rear, ready to move into prepared positions to fire on enemy armored penetrations. Because of its light armor and backblast, it may be necessary for an Ontos to displace to alternate positions after firing.

3) General support

Antitank units may be assigned in general support to provide antitank protection for the division as a whole and increase the flexibility of employment of antitank means. In this case, Ontos are centrally controlled. They may be held in assembly areas, deployed laterally and in depth, and prepared to occupy previously organized positions.

b. B. Mobile defense

1) Security echelon

If used with the security echelon, Ontos employment is the same as with security forces in position defense. The Ontos, with its firepower and great mobility, lends itself ideally to use with the mobile defense. Normally, the optimum employment of antitank units is in the forward defensive area or with the striking force.

2) Forward defensive area

Antitank units supporting forces in the forward defensive positions assist in canalizing the movement of enemy armor into predetermined killing zones. There the enemy is attacked by the striking force. This is accomplished by normal defensive employment of antitank units in coordination with other supporting arms, and the fire and maneuver of infantry units.

3) Striking force

The employment of antitank units in support of the striking force is similar to that of other offensive operations. Antitank units provide antitank protection of the striking force elements while in assembly areas and while moving to contact.


The Ontos is an effective ambush weapon to attack and decisively defeat tanks from covered and concealed positions. In an ambush the requirement to hold a position or a piece of terrain is not present.

a. Vehicle ambushes are most effective when set in defiles where the surrounding ground affords cover and concealment. The most suitable defiles are those easily blocked at both ends. The sides of the defile should be sufficiently impassable to prevent the enemy from escaping the killing zone or mounting an attack against the ambush site.

b. The commander of the ambush unit must have excellent observation of the killing zone and the approaches to it. He must be able to determine the most appropriate time to issue orders such as, commence fire, cease fire or withdraw.

c. .For an ambush to be successful, surprise must be complete. This demands strict camouflage and fire discipline.

d. The need for fire discipline demands firm control measures. The first element is radio discipline that permits clear transmission of fire commands and orders to withdraw. Prearranged signals, such as pyrotechnics and hand and arm signals must be planned for use in the event of radio failure. Preplanned and reconnoitered routes of egress to rendezvous points and alternate positions further aid control during displacement from primary ambush positions.

e. Security is maintained throughout the entire ambush operation, and particularly during displacement. Security, coupled with the proper use of barriers, must be utilized to prohibit enemy entry into the ambush site at any point other than those leading into the killing zone. Supported infantry may have to provide local security for ambushes established beyond the battle area of the supported unit. During displacement, units will provide their own route security. This is done by leapfrogging vehicles, and units, from one covering position to another.

f. Naval gunfire, artillery, and close air support employed in conjunction with antitank weapons enhance the effectiveness of the ambush. Support air has the best capability of intercepting enemy reinforcements and preventing their interference. Supporting arms may also provide fires covering the withdrawal from the ambush.

704 Roadblocks

Ontos are effective against enemy tanks attacking roadblocks.
a. Roadblocks are in many ways similar to ambushes. The main difference is the determination to hold the position. In the ambush there is seldom an intention to hold the ground. The roadblock is a position which is to be held for the purpose of denying ground or routes to the enemy for brief or extended periods.

b. The roadblock should include mines, abitis, tetrahedrons, or similar devices. This barrier should be covered by both small arms and antitank fire.
c. The critical area immediately in front of the roadblock should be covered by available naval gunfire, artillery, and air in conjunction with other available antitank means.


a. During withdrawals and retirements, antitank units may be deployed to cover tank approaches that threaten lines of communication to the rear. Some Ontos may be integrated with tank or infantry elements and used in the security forces, detachments left in contact, or rear guard.

b. A delaying action seeks to trade space for time and inflict maximum damage on the enemy without becoming so heavily engaged that freedom of action is lost. This tactic demands maximum fire power in support of units in contact with the enemy. It also dictates that units in contact be highly mobile so that they may disengage. Ontos are best employed in forward elements maintaining contact with the enemy where they will cause the enemy to deploy early, creating maximum delay.


Composition of mechanized task forces varies with specific operations according to mission, terrain, enemy situation and units available. When considerations favor employment of Ontos, units of the antitank battalion may be assigned to the task force. During marches, Ontos move with the main body. When the task force deploys, antitank units seek positions from which they can protect against enemy armor envelopments. When the task force is static, Ontos are deployed to add depth and breadth to the antitank defense.


a. The battlefield of the future will be porous, creating extensive need for reconnaissance and counterreconnaissance. Units assigned to active reconnaissance or counterreconnaissance missions should be mobile and strong in fire power, since they will be exposed to many meeting engagements. Ontos should not normally be used in offensive patrolling if tanks are available. However, there may be instances when a reconnaissance in force is carried out by a mechanized task force. If the patrolling unit is sufficiently large and strong in tanks, the Ontos may be assigned to toe patrol to lend additional antimechanized strength.

b. The Ontos is well suited to the counterreconnaissance mission. By use of ambush tactics it can engage enemy forces infiltrating the friendly battle area. When performing counterreconnaissance and screening missions it is necessary to integrate the Ontos with infantry, engineers, and—where possible—tanks. This integrated force should have on-call air support—for both destruction and observation missions—and artillery and naval gunfire when available.


The basic fundamentals involved in offense and defense at night are the same as those that prevail for daylight. However, at night the problem of control and coordination is greater, infantry and other units are positioned closer together, and movement is slower. Target acquisition and hit probability are drastically diminished. All of these difficulties can be overcome –to a degree – by skillful employment of illumination. If no illumination is available the Ontos should attack only those known or suspected point targets on which the weapons have been previously registered or laid. If an armored threat exists, illumination should be available on-call for Ontos units covering the most likely avenues of tank approach.


Antitank units may assist the entry of rifle elements into built-up areas. They occupy positions to fire overhead or through gaps in friendly lines. During fighting within built-up areas, antitank units occupy positions outside of the city to assist in isolating the area. They prevent enemy armored vehicles from entering or leaving the city. If the far edge of the town cannot be covered by fire from positions outside the town, Ontos may be moved through town to support the attack. They are not normally used within built-up areas without close covering support by the infantry unit with which they are operating.


In attack of a river line, elements of the division antitank battalion are usually attached to, or in direct support of, regiments making the crossing. Platoons may be further attached, or used in direct support of, assault battalions. Antitank weapons support an assault crossing by firing on enemy targets on the opposite bank. Priority of fire is given to enemy armor and crew-served weapons. Specific target areas are assigned each weapon. Following the crossing of friendly armor, high priority is given to the crossing of antitank units. Once antitank units are on the far shore and the initial objective is seized, these units are employed the same as for any other attack.


a. The situation may permit employment of Ontos in the attack of a fortified position. Ontos should be employed from covered and concealed positions as the base of fore element to support tactical maneuvers.

b. When the possibility of enemy armored activity is present, antitank units are deployed so as to react readily to enemy tank attack. Where obvious sally ports exist through which the enemy may mount armored counterattacks, Ontos should be positioned astride the most likely route of enemy advance. They may also be used to seal off exposed flanks of attacking units.


a. A crew of 7 men is desirable for a ground-mounted 106mm rifle – 3 men to carry the weapon, 2 to carry the mount, and 2 ammunition carriers. A 3-man crew is adequate when the ¼ -ton truck or similar vehicle is available to transport the rifle and its ammunition. The antitank battalion is not provided with sufficient personnel for complete gun crews when all ground-mounted weapons are employed. Consequently, when such employment is contemplated, the training of personnel from other units for this purpose is necessary. The number of men the antitank battalion can furnish for each crew will vary with the situation. Three situations, in this respect, are possible in combat:

1) The Ontos are employed, with no ground-mounted rifles involved.
2) The Ontos are employed concurrently with grounde-mounted rifles.
3) Ground-mounted rifles only are employed

b. Either the antitank unit commander or the supported unit commander may recommend or request the employment of ground-mounted rifles. Approval for such requests rests with the division commander, or, with the supported unit if the antitank unit is attached. Concurrence in the recommendation for such employment by the antitank unit commander is therefore a desirable prior to

c. Authorization.

d. Employment of Ontos rifles as ground-mounted weapons should be authorized only when:

e. An Ontos is immobilized.

f. Antitank positions are available, but inaccessible to the Ontos.

g. Extensive areas of operation require more widely deployed antitank protection than can be attained by employment of Ontos.

h. Employment of ground-mounted rifles results in reduced effectiveness and has he following disadvantages:

1) Reduction of Ontos firepower.

2) Reduced mobility of weapons.

3) Inability of the antitank battalion to provide all personnel required for ground-mounted weapons’ creqs.4) Reduced target acquisition ability and hit probability.


In emergency situations when tank support for friendly troops is not available, Ontos may fulfill, to a limited degree, the landing force’s requirement for mobile firepower and shock action.
A: This emergency use, however must be adopted only after careful consideration of the situation. In the face of enemy armor the employment of Ontos, in other than from hull defilade position, is undesirable. Likewise, the Ontos could not be expected to carry out offensive missions against direct fire, major caliber weapons. However, Ontos could be effective against such weapons if employed from covered and concealed positions, particularly from the flanks, wherein surprise is utilized to the maximum.

A: In exceptional circumstances, the enemy may consist of poorly trained and equipped troops. In this event, the Ontos may be used as a psychological weapon in a tank-like role.

The Ontos has the capability of being air-dropped or air-landed. This capability may be exploited in support of isolated units operating at some distance from a larger parent unit.




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