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APPENDIX H

ENEMY STRENGTH COMPUTATIONS

Enemy strength undergoes a continuous fluctuation between tables of organization and equipment (TOE)-type strengths and varying levels of force, unit, equipment, and personnel strengths during the course of a battle, campaign, or war. These fluctuations are a result of unit, personnel, and equipment losses and the enemy's ability or inability to provide suitable replacements quickly and consistently.

Enemy strength computations provide a method for estimating the level of combat effectiveness of enemy forces. It is computed in terms of committed forces, reinforcing and supporting units, and the number of nuclear weapons and chemical and biological delivery systems suspected or identified as being deployed within the friendly commander's area of operations, or interest.

Based on the analyst's knowledge of enemy doctrine, OB, and current information and intelligence on enemy dispositions, locations, and capabilities; the numbers of committed, reinforcing, and supporting forces can be computed.

Once these enemy forces have been determined, individual enemy units can be identified or located and enemy strength computed. Personnel and equipment strengths are described as percentages of known TOE-type strengths, based upon reported enemy personnel and equipment losses and known or estimated rates of replacement.

COMMITTED FORCES AND REINFORCEMENTS

Committed forces are those enemy ground units, in contact, whose area of employment is not expected to change to counter the specific course of action selected by the friendly commander. Committed forces may change disposition within their area of employment, but no significant delay is involved in their employment. Designation of enemy forces as committed forces depends primarily upon their disposition, location at the time of the estimate, and the echelon at which the estimate is being prepared.

Reinforcements are those enemy forces whose area of possible employment against the friendly force depends on the friendly selection of a specific course of action and on enemy capabilities. Reinforcements include all known enemy forces which are neither committed against a friendly force nor committed outside the friendly zone or sector, but which can reasonably be considered capable of closing with the friendly force in time to affect the accomplishment of the mission.

Estimates of NBC enemy capabilities usually are prepared at field army and higher headquarters. Units below field army level usually lack the means to gather the information to make such estimates. They use the estimates of the higher headquarters and modify them with available information.

The determination of enemy NBC operation capabilities is based primarily on estimates of numbers and types of weapons and amount and types of agents available, knowledge of enemy doctrine, past experience, and estimates of enemy capabilities involving the employment of ground troops. It is rarely possible to estimate what portion of the available enemy NBC effort may be used against a division or corps within a field army or a command in the communications zone. It is also rarely possible to estimate the number of nuclear weapons the enemy is capable of using within a period as short as one day. The period selected is a month or longer, depending on the available information and past experience.

The statement of the enemy's capability of using chemical and biological agents includes the amount, type, and delivery means of available agents.

COMPUTING COMMITTED ENEMY UNITS

The information provided by the G2/S2 on enemy committed forces and reinforcements is used by the commander and the operations officer for planning and conducting tactical operations. Accurate information is particularly important during the commander's analysis of opposing courses of action. For example, in planning for an attack, an overestimation of committed enemy forces and an underestimation of enemy reinforcements could cause the friendly commander to attack with a small reserve. The intelligence officer's error in computing committed and reinforcing forces could allow the enemy to counterattack with an unexpectedly strong force, inflicting unacceptable casualties upon the friendly force.

All uncommitted enemy forces are considered as reinforcements if they can be committed in time to affect the accomplishment of the mission. If there is doubt as to whether an enemy unit is committed or reinforcing, it is considered as a reinforcement. This reduces the risk of surprise.

Expressing strength in number of units, by type, within an enemy force is stressed because it is a simple, reliable, and readily understood method of computing enemy strength. At the same time, the OB analyst cannot ignore individual unit strength computations. This is particularly important in arriving at a true picture of the enemy's strength.

Strength by type of unit includes the total number of enemy units listed by category and type. Normally, enemy units are counted down to and including two echelons below the friendly force's level of command. Some special purpose units three echelons below may also be counted.

Usually, an intelligence officer accounts for committed enemy forces by the size of the enemy unit which is opposing the friendly elements. Against an enemy army, a division G2 usually counts committed forces in terms of battalions; a corps G2 in terms of regiments; and field army and higher headquarters, in terms of divisions. At headquarters above field army, a statement of the number of armies and army groups is also included. For example, "The committed forces facing this army group consist of one army group (3 combined arms armies with a total of 11 MRDs and 3 tank divisions). . . ." When committed forces, such as guerrillas, do not have a known organization, their strength is stated in total numbers.

The brigade S2 considers as committed forces the first and second echelon companies of enemy motorized rifle, tank, or reconnaissance battalions in contact with the brigade. Although the enemy company is the basic sizes unit used by the brigade S2 in accounting for committed forces, he will also account for smaller units which have been located as separately employed.

The battalion S2 considers as committed forces the first and second echelon platoons of the enemy motorized rifle, tank, or reconnaissance companies in contact with the battalion. Although the enemy platoon is the basic unit used by the battalion S2 in accounting for committed forces, available intelligence frequently does not enable the individual platoons composing the enemy company to be located. Therefore, the battalion S2 will consider that a located enemy company normally consists of three platoons; a company (-) consists of two platoons. The process of counting committed forces in the defense and in the offense is shown in the following illustrations.

The designation of enemy units as committed forces depends primarily on their disposition and location at the time the estimate is made. Enemy unit identification may facilitate determining if a particular unit is the reserve of elements in contact with the brigade or battalion.

When an enemy unit of the size used in accounting for committed forces is in contact with two adjacent friendly units, the entire enemy unit is considered to be committed by the G2 or S2 of both friendly units. For example, if an enemy battalion is in contact with elements of two adjacent US divisions, both division G2s consider the entire battalion as committed against their respective divisions. This points out the need for correct identification and accurate strength computation at each echelon.

All ground Fire Support (FS) weapons organic to the enemy MRB or MRR are referred to as normal regimental artillery and are always considered to be in support of committed forces. That is, each committed unit is assumed to have available to it its normal proportion of the available supporting weapons organic to the regiment. These weapons, therefore, need not be enumerated. FS weapons not organic to enemy motorized battalions or regiments which can be identified as within supporting range are enumerated as if in support of committed forces. In the event that the forces committed against the brigade or battalion have no known TOE (that is, volunteer or irregular-type units), all FS weapons which can be identified are enumerated.

When enumerating enemy forces, enemy security elements forward of the combat outpost line are normally considered reinforcements of the main defensive position until contact with these security elements is made. The intelligence officer must correctly identify the enemy's main defensive positions and must not be deceived by security forces. The security forces will normally become reinforcements for the main defense after completing their security mission.

In addition to determining the enemy's ground combat unit strength in terms of committed forces and reinforcements, the G2 or S2 also considers the enemy's air and nuclear weapons strength. However, as estimates of enemy air NBC warfare strength are usually prepared only at field army level and higher, the G2/S2 simply restates these capabilities in his estimate.

Reinforcements are stated conveniently and meaningfully. For example, if the opposing division has an MRR in reserve, this reinforcement is referred to as a motorized regiment rather than three motorized battalions. When enemy units--either committed forces or reinforcements--are very much under strength, the estimated remaining strength is expressed. Two divisions, each at half strength, are usually more formidable than a single division at full strength because of the added flexibility of employment and the additional combat support probably available. A half-strength field artillery battalion is more than half as effective as a full strength battalion.

When only two elements of a unit can be located, they are counted as they appear. By templating, it may be possible to determine the approximate location of the third element. Although this unit cannot be counted, the commander should be advised as to its possible location.

COMPUTING ENEMY REINFORCEMENTS

The time required for an enemy to move troops from one place to another and commit them is determined by factors derived from analysis of past similar enemy movements. The considerations described below are applicable in training and as a point of departure for the development of experience factors in operations against an enemy force.

To determine the time when the enemy can employ an uncommitted unit, the travel time from the unit location to a logical point where the unit can be committed is calculated. To the travel time, add the closing time (pass time of a column). Except when observation of enemy units is continuous, it is assumed that any unit could have started to move immediately after its last reported location. Therefore, to determine the earliest time at which the enemy can reinforce, add the travel plus closing time to the time last observed. For example, if an enemy reinforcement was last observed at 0800 hours, and it can deploy to envelop the northern flank in 1 hour, it is assumed that the attack can be launched as early as 0900 hours (0800 plus 1 hour). In the exceptional case involving piecemeal commitment of enemy reinforcements, consider travel time only. Forces which are committed piecemeal do not close into an assembly area or attack position.

Because observation of reinforcements is rarely continuous, statements of enemy reinforcing capabilities should include both the earliest time and that time after starting movement when the reinforcement can be accomplished. For example, "the enemy can reinforce his attack with the 45th MRR at 0900 hours, or 1 hour after starting movements." When the time since the last report is greater than the time after starting movement, only the time after starting movement is given. For example, "the enemy can reinforce his attack with the 45th MRR now or 1 hour after starting movement." When the number of reinforcements is large or the enemy is capable of reinforcing in several areas, reinforcing capabilities are presented in tabular form. For example, the enemy can reinforce his attack or his defense with all or part of the following units at the places and times indicated in the following chart.

In selecting a logical point for reinforcement, the effects of AO characteristics, such as avenues of approach and logical enemy reactions to friendly courses of action, are considered. For reinforcement of an attack capability, locations for second echelon commitment are selected for battalions and regiments and forward assembly areas for division and larger units. For units moving to reinforce a defense, defense or counterattack positions are selected. For movements by aircraft, logical LZs or DZs from which the enemy forces can materially affect the accomplishment of the mission are selected.

The time required by the enemy to issue extra ammunition, make detailed reconnaissance, issue orders, and deploy to a line of departure is not considered because all may be completed before starting the operation or simultaneously with movement.

The following guidance is applicable until experience factors against a particular enemy are developed:

• Compute foot marching time for all appropriate reinforcements. Compute motor movement time only for distances greater than 10 kilometers (6 miles). If a unit is observed in trucks, compute only the motor movement time.



• Consider a foot march of more than 32 kilometers (20 miles) as a forced march. Consider a motor movement of more than 280 kilometers (175 miles) as a forced march for motorized units and a movement of more than 224 kilometers (140 miles) as a forced march for tank units.



• Compute closing time at the night rate of march if a column begins to close before the BMNT closing time; if a column begins to close at or shortly after BMNT, use the day rate of march. If a column begins to close before the EENT, use the day rate of march; if a column begins to close at or shortly after EENT, use the night rate of march.



• Move and close the entire unit to move an enemy infantry battalion. To move a unit of regimental or larger size, move and close two thirds of the combat elements; that is, two battalions of an infantry regiment, two regiments of an infantry division.

COMPUTING COMBAT STRENGTH

The method for computing combat strength, as discussed in the preceding paragraphs, is illustrated in the following three situations:

SITUATION 1

The 20th Infantry Division is advancing to the south. The advance of the division has been stopped by elements of two MRRs (8th and 12th) of the enemy 16th MRD. Each of these MRRs has two MRBs in contact and one MRB in the second echelon. The third MRR (96th) is in contact with the 72d Infantry Division on the flank of the 20th Infantry Division. About 40 kilometers (25 miles) in rear of the 16th MRD and in the area of the 20th Infantry Division objective, two MRRs (43d and 75th) of the enemy 12th MRD are preparing field fortifications.

The four battalions of the 8th and 12th MRRs in contact with the 20th Infantry Division are considered as committed forces by the 20th Infantry Division G2. Regardless of the specific courses of action selected by the commander of the 20th Infantry Division to continue the advance, the area of employment of these four battalions in contact will not change appreciably. The second-echelon battalions of the 8th and 12th MRRs are not considered committed since they are not in contact and can be employed in other areas. The 96th MRR would be considered committed and mentioned in the composition subparagraph of the observation post (OP) order, but only its second-echelon battalion would be listed as a reinforcement by the 20th Division. The other two battalions are committed against the 72d Division and are not available as reinforcements against the 20th Division. The 43d and 75th MRRs of the 12th MRD are considered as reinforcements because these units are not committed against the friendly force and can be committed in time to affect the mission of the 20th Infantry Division. Although the two MRRs of the 12th MRD are digging field fortifications in the vicinity of the division objective, the enemy commander can employ these units against either the 20th Infantry Division or adjacent divisions. (See the following schematic sketch illustration.)

SITUATION 2

The 20th Infantry Division is attacking to the east. Enemy committed forces are the 3d MRB; 3d GMRR; three battalions of the 5th MRR, and the 1st Battalion; 7th MRR; the 2d Battalion; 33d GMRR is committed against units on the 20th Infantry Division flanks. The 1st and 2d Battalions, 3d GMRR and the 2d Battalions 7th MRR are not in contact and are second-echelon battalions which may be employed against the 20th Infantry Division. They are considered reinforcements. Two enemy MRR in the assembly area astride the 20th Infantry Division north boundary and the enemy MRR south of the south boundary are reinforcements. From their locations and dispositions, it is apparent that they are the reserves of the regiments committed against the 20th Infantry Division. Depending on the course of action selected by the commander of the 20th Infantry Division and the enemy plans, all or part of these enemy elements can be employed against the 20th Infantry Division, at various times and places; in time to affect the accomplishment of the division mission. (See the following schematic illustration.)

SITUATION 3

This example discusses the determination of enemy strength opposing the 1st Brigade, 21st Infantry Division, and each of its composite units: the 1st Battalion, 69th Infantry; and the 1st Battalion, 70th Infantry.

The 1st Brigade, 21st Infantry Division, with the 1st Battalion, 69th Infantry, and the 1st Battalion, 70th Infantry forward are defending positions as indicated in the schematic sketch illustration on page H-14. Reports from the 21st Infantry Division indicate the enemy has an unknown number of air and nuclear weapons available.

The S2, 1st Brigade, determines enemy strength as follows:

• Committed Forces; 1st Brigade is opposed by three motorized rifle companies, one reconnaissance platoon, and one medium tank company (13 tanks) supported by normal regimental artillery, plus two 160mm mortars, six 122mm howitzers, six 100mm AT guns (SP), and all available air and nuclear weapons.



• Reinforcements: Enemy reinforcements available for commitment in the sector of 1st Brigade are an unidentified MRB located in the vicinity of Hill 250.

The three motorized rifle platoons northwest of the Highway 82 bridge are disposed so that they logically constitute one motorized rifle company in contact with, and committed against, the 1st Brigade. The reconnaissance platoon southwest of Hill 200 and the motorized rifle company northeast of the Highway 82 Bridge are in contact with, and committed against, the 1st Brigade and its respective adjacent brigades. All three platoons of the company northeast of the Highway 82 bridge are considered as one company committed against 1st Brigade, since brigades account for committed forces in terms of companies. The motorized rifle company immediately south of Chigger Woods is located so that it is, logically, the reserve company of an enemy battalion in contact with 1st Brigade and is therefore considered committed. The motorized rifle companies of the 25th and 23d Regiments, located to the east and west of the 1st Brigade sector, are totally committed against adjacent brigades and are, therefore, neither committed nor available as reinforcements against 1st Brigade, 21st Infantry Division. Ten medium tanks are located in the vicinity of the motorized rifle companies committed against 1st Brigade and are, therefore, also committed. S2, 1st Brigade would be equally correct to account for these committed medium tanks as three medium tank platoons or ten medium tanks. (The three amphibious tanks organic to the reconnaissance platoon, although not specifically located at this time, are accounted for as normal components of one reconnaissance platoon.) The 85mm SP gun and 120mm mortars located north of the Muddy River are part of the normal regimental artillery. However, they are within supporting range and are, therefore, enumerated as in support of committed forces. The enemy also has an unknown number of air and nuclear weapons, which can be employed in support of committed forces.

S2, 1-69th Infantry, determines enemy strength now opposing the battalion as follows:

• Committed Forces: 1-69 Infantry is opposed by two motorized rifle platoons, one reconnaissance platoon, and one medium tank platoon, supported by normal regimental artillery, plus six 160mm mortars, six 122mm howitzers, six 100mm AT guns (SP), and all available air and nuclear weapons.



• Reinforcements: Enemy reinforcements available for commitment in the sector of 1-69 Infantry are an unidentified MRB located vicinity of Hill 250 and an unidentified motorized rifle company and medium tank platoon located vicinity of Chigger Woods.

One motorized rifle platoon is in sole contact with, and therefore committed against, 1-69 Infantry. The motorized rifle platoon north of boundary 1-69 and 1-70 Infantry is counted as committed against both 1-69 Infantry and 1-70 Infantry. The medium tank platoon in the same vicinity is in contact with and therefore committed against both 1-69 Infantry and 1-70 Infantry. S2, 1-69 Infantry, considers all of the reconnaissance platoons in contact because this is the size force the battalion S2 uses for computation of enemy strength. None of the tanks organic to this platoon have been specifically located at this time; however, they are accounted for as a normal component of the reconnaissance platoon. The motorized rifle company and tank platoon located vicinity Chigger Woods which are considered as committed by S2, 1st Brigade could logically be employed against 1-69 Infantry in time to affect the accomplishment of the battalion mission and are therefore considered as reinforcements. The discussion above concerning the battalion vicinity Hill 250, the normal regimental artillery and nonorganic weapons in support of committed forces, applies also to the determination by S2, 1-69 Infantry.

S2, 1-70 Infantry, determines enemy strength now opposing the battalion as follows:

• Committed Forces: 1-70 Infantry is opposed by four motorized rifle platoons and two medium tank platoons supported by normal regimental artillery, plus six 160mm mortars, six 122mm howitzers, six 100mm AT guns (SP) and all available air and nuclear weapons.



• Reinforcements: Enemy reinforcements available for commitment in the sector of 1-70 Infantry are an unidentified MRB located vicinity Hill 250 and an unidentified motorized rifle company and medium tank platoon located vicinity Chigger Woods.

S2, 1-70 Infantry, considers the individually located motorized rifle platoons vicinity boundary 1-69 Infantry and 1-70 Infantry in the same manner as does S2, 1-69 Infantry.

Two platoons of the motorized company northeast of Highway 82 bridge are considered committed against 1-70 Infantry. S2, 4-80 mechanized, could also consider two platoons of this company committed against this battalion. The discussion concerning reinforcements and supporting fires supporting fires applies also in the determination by S2, 1-70 Infantry. (See schematic sketch, situations.)

COMPUTING COMBAT POWER

To compute combat power, the following terms must be thoroughly understood:

• War established strength.



• Effective strength

War establishment strength is the maximum number of personnel or equipment that a unit would be authorized to have in time of war. Equipment includes both weapons and ammunition, as well as common and specialized equipment provided to a unit from established TOE-Type documents. War establishment strength is also referred to as full wartime strength.

Effective strength is the assessed number of personnel or equipment in a unit that is currently capable of combat employment. It is usually expressed as a percentage of the war establishment strength. Effective strength can be broken down by type of unit and is expressed as Infantry, Armor, Artillery, or air strength.

The calculations, expressed as percentages of the war establishment strength, are computed as follows. (Where it is apparent that a percentage does not accurately reflect the fighting ability of a unit, it may be necessary to elaborate on this figure.) To estimate equipment strengths, the following formula is generally used:

        Where:

        Wt = war establishment tanks

        Wa = war establishment APCs

        Wg = war establishment artillery guns

        Lt = Assessed losses tanks

        La = Assessed losses APCs

        Lg = Assessed losses artillery guns

        Rt = Assessed reinforcement or replacement tanks

        Ra = Assessed reinforcement or replacement APCs

        Rg = Assessed reinforcement or replacement artillery guns

Equipment and personnel estimates will need to take account of all relevant information, such as the items listed in the equipment strength calculation considerations chart.

Personnel strength is expressed as percentages of TOE strength where possible. However, a numerical expression of "bean count" may be necessary to present a better understanding of the combat capability of a force, and provide the commander with a basis for comparison. The computation of enemy strength requires the utmost caution and alertness for intelligence that may reveal the enemy's actual strength. This is especially true at the onset of hostilities, when accurate intelligence pertaining to enemy strength is lacking or inadequate, and the initial strength figure is only an approximation. The formula is as follows:

In time of peace, personnel strength generally is computed by annual induction quota, multiplied by the term of conscription, plus cadre, as follows:

The information in the following personnel strength calculations considerations chart should be considered when computing personnel strengths.

Combat loss data, resulting from post-attack assessment, provides input to compute enemy strength. Information concerning strength also provides indications of enemy capabilities and assists in determining the probable courses of action or options open to enemy commanders. A lack of, or a superiority of, strength has the effect of lowering or raising the estimate of the capabilities of an enemy force. Similarly, a marked concentration of units in an area gives indications of enemy objectives and probable courses of action. During peacetime, changes in the strength of potential enemy forces are important factors which indicate the enemy's intention and capability to wage war.