THE ORGANIZATION OF ARMIES

Introduction

Since the time of Napoleon, the primary unit around which European armies have been organized has been the "division," a unit that contained all the elements necessary to sustain itself in combat. Thus, a Napoleonic division (which numbered about 10,000 men) was composed of infantry, artillery, cavalry, and supply units.

Divisions can fight on their own, or they can be combined with other divisions to form a larger unit, a "corps" (2 or more divisions); corps can be combined to form an "army" (2 or more corps); and armies can be combined into "army groups" (2 or more armies).

Divisions, on their own part, are made up of a number of smaller units. In the European and American armies of World War I and II, the largest of these subunits were called "brigades" or "regiments." These brigades or regiments were in turn are made up of a number of "battalions," which were made up of a number of "companies," which were made up of a number of "platoons."

The purpose of this memorandum is to provide some information about the numbers of men and weapons that made up these various units during World War I and II and to describe some developments since 1945.

Students are not expected to master or remember the details in this memorandum, but reading it will enable them better to understand what is involved when references are made to these units in the assigned readings or in lectures.

It is important to note that the numbers provided are illustrative only and that these numbers are not easily compared. For example, the size and composition of infantry divisions in the two world wars differed not only from country to country and from war to war, the structure of a country's infantry divisions frequently changed during the war. Moreover, even divisions with the same structure were not always of the same quality (in 1918, for example, the German army distinguished among first, second, and third-line infantry divisions). Finally, each country also maintained several kinds of divisions during these wars (e.g., infantry and cavalry divisions in World War I; and infantry, cavalry, armored, motorized, mountain, and airborne divisions in World War II).

During the Cold War, the NATO and Warsaw Pact forces that confronted each other on the Central Front (the FRG-Czech frontier) were very different in both the size and composition of the units deployed and in the kind and number of weapons with which they were equipped. As a result, a methodology was developed for measuring and comparing the military effectiveness of the variety of weapons and national forces involved (using a unit of account called an "armored division equivalent") in order to model the outcome of possible wars on the Central Front. Students interested in consulting some of this literature should see me in office hours.

After reading this memorandum, all students will understand why analysts tried to develop the methodology.

Units in World War I

The number of men in the infantry divisions deployed by the Great Powers in 1914 ranged from about 16,000 in the Russian army to about 18,000 in the British.

A British infantry division in 1914 was composed of 3 brigades. Each brigade had 4 battalions; each battalion had four companies; and each company had 4 platoons. Thus, the division had 12 battalions.

At full strength, a battalion had 35 officers and 1000 men, and a company had 5 officers and 240 men. In addition to rifle power of its battalions, the division was armed with 24 machine guns, and its field artillery numbered 76 guns (54 18-pdrs. [84mm]; 18 4.5" howitzers; and 4 60-pdrs. [127mm]). The division had in addition various headquarters and supply units and 5592 horses for transport.

The 1914 German infantry division was comparable in size, 17,500, and was organized into 2 brigades. Each brigade had 2 regiments; each regiment had 3 battalions; and each battalion had 4 companies. Thus, the division had 12 battalions.

At full strength, a battalion had 26 officers and 1050 men, and a company had about 240 men. In addition to its rifle power, the division had 24 machine guns, and the field artillery numbered 72 guns (54 77mm guns and 18 105mm guns). In addition, the division had various supporting units (cavalry, engineering, medical, etc.) and 4000 horses for transport.

As an example of larger units, the German Army (as did the British and French) started the war with 2 infantry divisions per corps. The German corps, in addition to containing supply, communication, and hospital units, provided heavier artillery for the support of the divisions. In 1914, a German corps provided either 32 150mm howitzers or 16 210mm howitzers for the support of its two divisions.

In the 1914 attack, the German First Army (the one closest to the channel, Gen von Kluck's) numbered about 320,000 men (not counting cavalry divisions) and was organized into 7 corps (each with 2 divisions) and supported with 3 Landwehr brigades.

As World War I went on, the size of divisions decreased significantly from those of 1914, and by 1918, many British infantry divisions were down to about 15,000 men. In part, this was because in 1918 the number of battalions per brigade was reduced from 4 to 3 (thus the division contained 9 rather than 12 battalions), and in part because reinforcements did not fully replace losses (battalions might number 800 or 900 men rather than the authorized 1000).

This reduction in manpower had occurred earlier in German infantry division. In 1917, the Germans eliminated their brigade structure and reduced the number of regiments in the division from 4 to 3, each regiment having 3 battalions. Thus, the German division now had only 9 battalions. In addition, the Germans, unlike the British, also reduced the number of companies in a battalion from 4 to 3. The result was to reduce the number of riflemen in the division from 11,520 to 6,460.

What the German 1917 division lost in rifles, however, it more than gained in other weapons. A division now had 48 mortars, a weapon not in its 1914 inventory, and by the winter of 1917-18, the number of machine guns had increased from the initial 24 to 358 (142 heavy and 216 light).

In contrast to the reduction in the number of battalions in divisions, as the war went on, there was an increase in the number of divisions contained in corps. In 1918, for example, one of the 3 German armies that mounted Operation Michael (the 17th Army, Gen. von Below's) was organized into 4 corps containing a total of 18 divisions.

The need to think in terms of "division equivalents" is best illustrated by the size and composition of the American infantry divisions that arrived in France: these numbered 28,061 officers and men.

The division had 2 infantry brigades, each with 2 regiments, with 3 battalions per regiment, and 4 companies per battalion. A company had 6 officers and 250 men, and the strength of a regiment was 112 officers 3720 men. All told, the division had 17,666 riflemen, 260 machine guns, and 72 guns (48 75mm and 24 155mm), along with various units for engineering, communication, and supply.

Obviously, a 1918 American division was roughly equivalent to about two post-1917 German divisions.

As for larger units, an American corps consisted of from 2 to 6 divisions (and contained a number of artillery, engineering, signal, and supply units to support its divisions), and an American army consisted of from 3 to 5 corps.

Units in World War II

The authorized strength of an American infantry division in 1944 provides an excellent example of the building-block character of military structure. The division totaled 14,253 officers and men and was organized on a triangular basis.

Three squads (each composed of riflemen and one light machine gun and commanded by a sergeant, a non-commissioned officer) made up a platoon, a unit of about 40 men commanded by a second lieutenant.

Three rifle platoons plus a weapons platoon (machine guns) plus supporting troops made up a company, a unit of about 193 men, commanded by a captain.

Three rifle companies plus a weapons company (mortars and machine guns) and a headquarters company made up a battalion, a unit of about 871 men and commanded by a lieutenant colonel. Three battalions together with artillery and other supporting units made up a regiment, a unit of about 3,118 men and commanded by a colonel.

Finally, three regiments plus additional artillery and other supporting units (engineer, signal, medical, etc.) made up the division, commanded by a major general.

Corps were commanded by lieutenant generals, and armies by generals.

The structure of a 1944 infantry division together with a list of its vehicles, artillery, and anti-tank guns is



pictured here. In addition to the weapons listed there, the division was armed with 144 mortars; 393 machine guns; 90 submachine guns; 557 anti-tank rocket launchers; 5,204 carbines; and 6,761 rifles.

Also pictured is the structure of a 1944 American armored division. This division had 10,998 officers and men and 269 tanks. In addition to the artillery and anti-tanks guns listed there, the division was armed with 111 mortars; 869 machine guns; 2,803 submachine guns; 607 anti-tank rocket launchers; 5,228 carbines; and 2,063 rifles.

The organization of the American First Army on the eve of Operation COBRA is pictured here. Note that each of the four corps contained a different number of divisions.

As this chart shows, the First Army, in addition to commanding the four corps, had a variety of supporting military units under its own command. Similarly, each corps, in addition to commanding its divisions, had additional military units under its own command, including additional artillery and tank battalions.

By 1 August 1944, the Americans had 21 divisions in Normandy, and Gen. Bradley's 12th Army Group was established to command these divisions. They were divided into 2 armies (the First and the Third) with each containing 3 corps.

When Germany surrendered on 7 May 1945, the 12th Army Group commanded 4 armies, organized into 11 corps, containing 43 divisions. (An additional American corps with 4 divisions was attached to the British 21st Army Group).

British infantry divisions in World War II, in contrast to the case in World War I, grew larger rather than smaller as the war went on.

In September 1939, a British infantry division (organized into 3 brigades with 3 battalions per brigade) numbered about 13,600 officers and men.

The division contained a machine gun battalion (740 men and 48 heavy MGs) and 3 field artillery regiments (each with 580 men and 24 guns, either 4.5" howitzers or 18-pdrs [84mm]).

The infantry battalion numbered about 780 men and was composed of 4 rifle companies and a headquarters company. The battalion was armed with 734 rifles, 58 light machine guns, 14 mortars, and 22 anti-tank rifles.

By 1944, a British infantry division (still organized into 3 brigades with 3 battalions per brigade) numbered 18,347 officers and men and was, thus, larger than an American infantry division.

The division still had 48 heavy MGs and 72 field guns (these were now 25-pdrs [87mm]), and the rifle battalions had increased only to 821 officers and men. The increase in the total number of men in the division was due mainly to increases in the size of supporting units (e.g., engineering, anti-tank, and anti-aircraft personnel).

The British armored division in 1944 numbered 14,964 officers and men, which made it also larger than the comparable American unit. The division had 290 tanks (as compared to the American 269) and was supported with, among other arms, 48 25-pdrs. [87mm]; 160 mortars; 22 heavy MGs; 78 anti-tank guns; and 141 anti-aircraft guns. In addition to its tanks, the division had 100 armored cars, 261 armored tracked vehicles, and 2098 trucks.

German units in World War II are less easily described. In 1939, the German army not only had five different kinds of divisions (infantry, motorized infantry, armored, mountain, and light), there were five different kinds of infantry division.

The largest infantry division had 17,700 men organized in 3 regiments each with 3 battalions. The division was armed with 75 guns (ranging from 75mm to 170mm); 147 mortars; 75 anti-tank guns; 138 heavy and 378 light machine guns; and 12 anti-aircraft guns.

The smaller infantry divisions had some 15,000 men and were less heavily armed.

The German armored divisions in 1939 had about 11,790 men and 328 tanks. The division was organized into 2 brigades. The tank brigade had two regiments, each with 4 battalions, and the infantry brigade had one regiment of motorized infantry and a number of supporting units (e.g., reconnaissance, engineer, signal, artillery). In addition to its tanks, the division had 36 guns (ranging from 75mm to 170mm); 48 mortars; 48 anti-tanks guns; 46 heavy and 180 light machine guns; and 12 anti-aircraft guns.

When the Germans attacked in the west in May 1940, they attacked with 3 army groups. Army Group A (von Rundstedt's) had 3 armies comprising 13 corps and containing a total of 45 divisions. Of these 7 were armored, and their tank strength ranged from 218 to 324, with an average of 258 tanks per division.

By 1944, German infantry and armored divisions had changed significantly.

The armored (Panzer) division now numbered 14,750 men and had about 160 tanks. The division was organized into an armored regiment with two tank battalions and 2 regiments of infantry, each with 2 battalions, along with various supporting units (reconnaissance, engineer, signal, etc.). In addition to its tanks, the division was armed with 77 guns (ranging from 75mm to 150mm); 70 mortars; 33 anti-tank guns; and 700 machine guns; and some 100 anti-aircraft guns.

Waffen-SS armored divisions had 6 rather than 4 battalions of infantry, and some divisions totaled as many as 20,000 men.

German motorized infantry divisions (Panzer Grenadier), i.e., those not dependent on horses, also contained 14,750 men. These were organized into 2 regiments, each with two battalions of infantry. These divisions were equipped with supporting units and weapons comparable to those of an armored division except that the motorized division had no tanks. It did have 45 assault guns (these guns were on an armored tank chassis but not in a traversing turret)

Some 1944 German infantry divisions had 9 battalions and numbered about 15,000 men, but most infantry divisions were organized in 3 regiments with only 2 battalions per regiment.

The 6-battalion divisions numbered about 12,500 men. The division was armed with 24 infantry guns and howitzers (75mm and 150mm); 48 field and medium guns (105mm and 150mm); 76 mortars; and 650 light and heavy machine guns.

For transport, the division had 615 motor vehicles and 1,450 horse-drawn vehicles.

This page presents a comparative summary of the strengths of British, American, and German infantry and armored divisions in 1944.

Although some of the numbers in this summary differ from those presented in this memorandum, the summary is close enough for illustrative purposes. Bear in mind that these figures are authorized numbers. Actual strengths varied from unit to unit, and were always less after combat, especially in the case of German units.

These numbers do not, of course, take account of any qualitative differences in the weapons involved. German light MGs, for example, had a higher rate of fire than the British and American, and German tanks were better armed and armored than the Allied tanks but were mechanically less reliable.

It is important to remember that each of these divisions was supported by a much larger number of men assigned to various other units (corps, army, transport, supply, etc.). On average, a British division was backed up by about 25,000 such men, and an American division was backed up by about 30,000 men. In both armies, the resulting total, known as a "division slice," was about 42,000 men.

Soviet units in World War II are not readily compared with those in the German and Allied armies..

A Soviet "Tank Corps" numbered 10,500 men and contained 189 tanks. A Soviet "Mechanized Corps" numbered 16,000 men and had 186 tanks. (These "corps" are more comparable to Western divisions than to Western corps.) A Soviet "Rifle Division" totaled 9,375 men, and a "Guards Rifle Division" had 10,585 men.

Two or three of these units made up a Soviet "Rifle Corps," and about 3 of these made up a Soviet "Army," and a Soviet army group, called a "Front," contained from 3 to 9 Armies.

Military ranks also differed from country to country, and in the case of some countries even from war to war. To illustrate some of these differences, a page comparing American and German army and navy ranks is presented here.

Some Cold War Developments

Throughout most of the Cold War, the United States deployed one army in Europe, together with some independent brigades and regiments. Upon mobilization, this army was to be reinforced by divisions brought from the United States.

The Army planned to fly the personnel of some divisions to Europe, where they would join with their equipment pre-positioned there, but most of these reinforcing divisions would have to come, as had their predecessors in World War I and II, by sea.

The American army deployed in Europe had 2 corps and a total of 4 divisions. Two of these divisions were armored, and two were mechanized.

Mechanized divisions were developed after World War II. Near the end of that war, the United States formed additional tank battalions (beyond those assigned to armored divisions) and began to attach a tank battalion to each infantry division in order to increase its fighting power.

After the war, infantry divisions were given their own tank battalions, and the resulting formation was called a mechanized division.

Both the armored and the mechanized divisions were subdivided into 3 brigades, but unlike the case with the regiments of the World War II divisions, the brigades did not have a fixed number of battalions assigned to them. The division had the flexibility of assigning, for example, 3 or 4 battalions to a brigade.

Since the armored and the mechanized divisions were now both composed of tank and infantry battalions (now called mechanized battalions), the main difference between the two divisions was in the mix of these two kinds of battalions.

In 1979, for example, an armored division had 6 tank battalions and 5 mechanized battalions. The division had 16,850 men and contained, among other units, 324 tanks; 555 armored personnel carriers; 344 anti-tank missile launchers (including 90 long-range TOW launchers); 98 107mm mortars; and 2,880 small arms.

The mechanized division had 4 tank battalions and 6 mechanized battalions. The division had 17,800 men and contained, among other units, 216 tanks; 583 armored personnel carriers; 402 anti-tank missile launchers (including 108 TOW launchers); 103 107mm mortars; and 3,456 small arms.

Both divisions had the same units for artillery (54 155mm guns and 12 8" guns [203mm]); aviation (171 helicopters, including 51 attack helicopters); and air defense (24 20mm Gatling guns, and 24 Chaparral missile launchers).

By 1988 and the end of the Cold War, the armored and mechanized divisions were almost identical in their composition and equipment except in the mix of their tank and mechanized battalions. Each now contained 10 battalions. The only difference was that the armored division had 6 tank battalions and 4 mechanized battalions, whereas the mechanized division had 5 tank battalions and 5 mechanized battalions.

The armored division now had 16,530 men and contained, among other units, 348 tanks; 316 armored personnel carriers; and 788 anti-tank missile launchers (including 362 TOW launchers).

The mechanized division now had 17,300 men and contained, among other units, 216 tanks; 370 armored personnel carriers; and 856 anti-tank missile launchers (including 370 TOW launchers).

Artillery for each division was now 72 155mm guns and 9 MLRS (Multiple Launch Rocket System). (The 203mm guns had been assigned to the corps.)

The aviation unit now had 125 helicopters, including 42 attack helicopters. (The crops had a larger helicopter force: 435 helicopters, including 117 attack helicopters.)

The air defense unit now had 24 20mm guns; 24 Chaparral missile launchers; and 78 Stinger [hand-held] missiles. (The corps had a larger air defense unit: 36 20mm guns; 108 Chaparral launchers; 8 Hawk launchers; and 90 Stingers.)

*********************

Nothing, of course, remains the same, and in 1997, an armored division now had 17,756 men, and a mechanized division had 17,982 men.

For comparison, the total personnel in the Army's other divisions in 1997 numbered: Airborne, 13,242; Air Assault, 15,840; and Light Infantry, 11,036.

Those interested in current units and weapons should peruse <http://www.defenselink.mil>.