Part I: England
Part II: Germany
Part III: Soviet Russia

In 1918 the U.S. Army's division structure contained 12 infantry battalions and 9 Artillery battalions which made it the largest and most powerful infantry division in the war (at 28,000+ men), and very different from that of all other combatants, whose priority was to spread their diminishing manpower pool as far as they could. In spite of this considerable difference in structure, the U.S. Army was heavily under the influence of French staff and tactical doctrine. This is logical since the Americans had to learn to do business in a manner compatible with the French units they fought alongside on a daily basis. As a result of this, immediate postwar doctrine in the U.S. Army paralleled that of the French Army. Tank forces were subordinated to the infantry branch.

Initial postwar regulations reflected the French view of combined arms so faithfully that the 1923 "Provisional Manual of Tactics for Large Units" didn't even bother to mention that it was a direct translation of the 1921 French "Provisional Instructions". The same year the U.S. revised its "Field Service Regulations," which insisted that "no one arm wins battles. The combined employment of all arms is essential to success." In the next paragraph, however, it stated that the mission of the entire force "is that of the infantry." You have to admit this is a pretty rigid view of "Combined Arms" doctrine!

It didn't effect all American military men, nor did it last for any appreciable length of time. As early as 1920, staff officers such as Brig. Gen. Fox Conner decided that trench warfare was inappropriate for operations in North America, which was the expected arena of future American warsl Conner asked Gen. John J. Pershing, the U.S. wartime commander in France, to discard the "square" division structure above as too immobile and unwieldy for future requirements. Pershing's answer was to reorganize the U.S. infantry division along the lines of the European "triangular" divisions. Specialized units which would only be required from time to time would be pooled at the level of Corps and Field Army. When the army attempted to apply the principles of this reorganization, it was found that a comprehensive review of the most fundamental relationships between the various combat arms and services was required.

A number of boards were organized to review the American experience in WWI. These recommended slight changes in the "square" division's organization during the 1920's. By 1925, U.S. Officer education focused on mobile warfare, with trench warfare relegated to the status of a 1. special operation." But financial restrictions and general governmental neglect prevented major reforms in organization or improvements in equipment until the mid 1930's.

At this time the "New Deal" released public works funds to the army to jumpstart the depression-gutted U.S. economy. These funds were used to purchase vehicles for the partial motorization of active duty and National Guard divisions, and the production of improved carriages with pneumatic tires for existing artillery weapons. This was important because, without pneumatic tires, guns could not be towed at the high speed of which motor transport was capable.

In 1935, Gen. Malin Craig became Army Chief of Staff. Craig had listened to Conner and the other reformers and instigated a review of all combat organization and tactics. He specifically suggested that the old "square" division be replaced with a smaller, more mobile one using mechanical power to replace muscle power wherever possible.

The proposed new division totaled only 13,552 men and much more closely resembled European "triangular" divisions existent at the time. From 1936-1939 it was the 2nd Infantry Division which had the honor of conducting extensive tests of the new concepts involved including such things as:

1. Firepower and frontage allocated per man and per unit.
2. The proportion of artillery and transport allocated for support.
3. At what level should which weapons be pooled? (Plt, Co, etc.)

The driving force behind the tests was Brig. Gen. Lesley J. McNair, the same man who later designed and trained the Army Ground Forces of World War II.

McNair's organization was quite similar to the theoretical organization proposed by Pershing and Conner in 1920. Machineguns and other specialized heavy weapons were integrated into the infantry rifle organization at every level, and the system was to be triangular! Each commander had a headquarters and "three" subordinate rifle (maneuver) units, plus a weapons unit. Three rifle platoons + weapons platoon per company, three companies + weapons company per battalion etc. There was tactical flexibility in that commanders might shift companies between battalions or battalions between regiments, but, by doctrine, all units operated with three subordinate maneuver units.

Each echelon also had a combination of flat-trajectory and high-angle weapons. There was a flaw in this new organization, however. The emphasis was on "mobility" over firepower. The U.S. platoon had nothing heavier than the BAR (a poor substitute for a true machinegun), which was only slightly mitigated by the rapid fire ability of the M1 Garand, and the company had nothing heavier than the 60mm mortar. Since U. S. tactics were based on the establishment of a base of fire and the maneuvering of a light force in conjunction with that base, this organization left U.S. infantry at a disadvantage.

The "pooling" principle continued throughout the division. Light AT guns, 81mm mortars, and machineguns went to the heavy weapons company of the battalion. Specialized arms such as tanks, AA guns, and most AT guns were 'not' authorized within the division, because McNair believed these weapons should be held in a central mass to be deployed decisively and not dispersed. Also the division got only one 'recon' troop. Long range recon was to be provided by higher echelons.

The result was a unit that was more mobile and heavily armed than before, yet seriously deficient compared to most foreign armies! Its principle weakness, in addition to insufficient automatic weapons, was its limited capacity for AA and AT defense. The effects of "Blitzkrieg" forced the army to realize that it had better strengthen both these arms.

The controversies over the triangular division included how much artillery support would be needed (originally three mixed 75mm gun/81mm mortar bns and one 105mm howitzer bn!) and how many engineers (if any!).

The June, 1941 organization represented the final phase prior to the American entry into the war:

1 x Division HQ & MP Company
1 x Armored Cavalry Troop (Company)
1 x Engineer Battalion
3 x Infantry Regts @ 3x Infantry Bns,
1xATG Co(37mm),
1 xHQ&SVC Co
1 x Artillery Regt @ 1 xHHB,
3xArty Bn @ 3x105mm Btty,
1x37mm ATG Co
1 x Heavy Arty Bn @ 3x 155mm Btty,
1xMxd ATG Co (37mm/75mm)
1 xHHB

for a total of 9 infantry bns, 60 37mm ATG, 8 75mm ATG, 36 105mm howitzer, and 12 155mm howitzer.

The most important factor in the increase of real combat power in the new division came from developments at the Army Field Artillery School. There the problem of massing fires on targets of opportunity was being revolutionized by a series of dedicated and brilliant veteran/ instructors.

During WWI, massed fires were normally set up in carefully planned concentrations, where previously established targets were pinpointed on maps and overlays. If some new target presented itself, it was difficult to bring more than one battery to bear on it. The reasons are a bit complex, so bear with me. A battery forward observer had to both be able to see the target and communicate with his battery. This meant he had to keep in telephone contact through vulnerable land lines. You can imagine how tough it would be to keep this line open and advance with the infantry being supported.

Some forward observers did mange it from time to time, (for which they were probably decorated!) but even if they did, there was no way they could guide other batteries to any new target, unless its map location had previously been 'precisely' established. However, by 1941 a means of concentrating any amount of artillery fire on a given target of opportunity had been developed.

Step one was to provide new and more reliable radios to largely replace field telephones in fluid situations. The second step was procedural. The impact of artillery shells and adjustments to them had always been recorded on firing charts oriented from the point of view of the battery location. All these calculations would now be recorded from the F.0's point of view!

Firing tables compensated for differences in location for various batteries, and one artillery weapon (known to us gun-grapes as the 'base piece') in each battalion was surveyed in relation to a common reference point for all guns in that divisional area. (You'll excuse me if I get excited about this. I cut my Marine Corps teeth in 11th Marines as a gun- gorilla on O-Fives and FiveFives!)

The result of this was that FDC's (Fire Direction Centers) could now provide one infantry unit with a whole battalion, or a whole regiment, or even more, of supporting artillery which could be controlled by only one observerl By contrast, throughout WWII, German artillerymen had to use well-known terrain features to adjust on a target of opportunity; massing fires remained extremely difficult. The new FDC's gave the U. S. a previously impossible degree of infantry-artillery integration. It also encouraged the U.S. to maintain large amounts of non-divisional artillery to be parceled out as needed.

When it came to the development of armored and mechanized forces, the U.S. wasn't so advanced. We were saddled with a tank inventory of left over WW I tanks models and a doctrine of subordination of the tank arm to direct infantry support. Luckily, the British experiments of the late 1920s, combined with the efforts of a certain persistent cavalry officer named Adna Chaffee Jr., led to a series of limited steps in the mechanization of U.S. Forces.

The Tank School at Fort Meade Maryland formed the (EAF) Experimental Tank Force in 1928 - 1929. It consisted of two battalions of obsolescent tanks, one of truck-borne infantry, an armored car troop, and small elements of engineers, signals, medical, ammunition, chemical warfare, and maintenance troops.

The force suffered frequent breakdowns, but the experiments aroused enough interest for a more permanent force to be established at Fort Eustis in 1930. The unit was disbanded after only one year due to lack of funds ('The Great Depression', remember?). It was absorbed by the Fort Benning Infantry School as "The Tank School" along with the remaining tank units.

During his tenure as Army Chief of Staff from 1930-1935, Douglas MacArthur was an advocate of motorization and mechanization throughout the army. The budget in those days made this impossible, but Chaffee persuaded him to conduct limited experiments with cavalry units. This was in their own best interest since the mounted arm's whole existence was at stake during the inter-war period. In the U.S., tanks were part of the infantry branch 'by law' so the cavalry simply called their tanks 'combat cars' (virtually the same models as the infantry's tanks). In 1932 a one-squadron cavalry regiment moved to Camp Knox, Kentucky, followed by another in 1936. These became the 7th Cavalry Brigade (Mechanized).

This force had the same weaknesses as European mechanized cavalry. It was too lightly armed and armored and considered useful only for raiding and pursuit. No matter how hard Chaffee tried he could only get the other arms to train with his brigade periodically. It wasn't until January, 1940 that the brigade was authorized an engineer troop, and at about the same time received an infantry regiment (the 6th). Also a "Provisional Tank Brigade" was formed out of various units at Fort Benning. Then everything hit the fan in May 1940!

The U.S. Army was now hot to make real progress in the development of mechanization. To avoid branch prejudice, Chaffee convinced the War Department to create an independent "Armored Force" as an arm in its own right. In July 1940 the 7th Cavalry Brigade and the Provisional Tank brigade became the nuclei of the first two U.S. armored divisions.

Like everyone else's early armored divisions, these were very tankheavy. Each possessed 6 light and 2 medium battalions of about 400 tanks in all, with only two battalions of armored infantry and three of artillery. There weren't enough infantry to support the tanks and the majority of the tanks were too light to stand up to the heavier German models. Obviously, more development and mass production were required.

Lastly, close air support was lacking in the U.S. combat team. In spite of the efforts of a few aviators such as Frank Lackland, the U.S. was preoccupied with strategic bombing to the neglect of close air support. This view overlooked certain vital aspects of ground combat: the psychological impact of close air attack, the principle of "Mass' which states that all resources must be concentrated to overcome the inherent advantages of the defense in modern war, and the need to achieve this concentration rapidly enough to prevent the defender from reorganizing and concentrating his own forces and therefore sustain mobility.

All three of these aspects argue for close air support at the critical point, but in 1939 only the Luftwaffe had made even limited preparations to provide it.

Prior to the Japanese attack on Pearl Harbor in December of 1941, the U. S. was an interested observer of WW II. Most of the U.S. Army didn't become involved in the war until the end of 1942 or later. During the 'Neutral Period', however, the U.S. drew certain conclusions about weapons, organization, and tactics, and continued the evolution of its triangular infantry division and the 1940 armored division. Maneuvers held in the U.S. and initial combat experiences overseas forced certain changes in American doctrine. The resulting system was to dominate our military well into the 1950's.

In March 1942, Lt. Gen. Lesley McNair, (remember him?) one of the designers of the triangular division in the 1930's, became head of Army Ground Forces. His duties included training and organization. His vision of the 'standard' organization was based on the idea that each unit should have only the minimum essential forces needed to conduct offensive operations in a fluid environment against relatively limited resistance.

For the infantry, this meant the three infantry regiments of the division, the four artillery battalions, the reconnaissance troop, and the engineer battalion developed between 1937-1941.

McNair's real contribution was in streamlining the division structure. Special purpose units, particularly those whose mission was primarily defensive (e.g., AA and AT units) were 'Pooled' in non-divisional companies or battalions that higher headquarters could parcel out on an 'as needed' basis, specifically for employment in mass at critical points. The actual combat potential of a division, therefore, could change from day-to-day or mission-to-mission.

McNair went even further by encouraging the formation of ad hoc task forces for flexibility and the abolition of all non-divisional regiments. When not part of a division for a specific mission, armor, anti-aircraft, field artillery, mechanized cavalry, and combat engineer battalions reported to 'group' headquarters. The number of battalions in a group was irrelevant.

McNair also shrank the staff and support elements to reduce paperwork and organizational obstacles to deci. sion making and demanded that specialized units be equipped with the necessary weapons to perform as infantry or rear area security forces when needed.

His final contribution, and probably his most important, was to restrict the amount of motor transport in each unit as much as he could to facilitate ' strategic' movement. Shipping space was at a premium and McNair wanted to get as much 'Bang' to Europe and the Pacific as possible for each shipping tonnage 'Buck'. He sought to authorize only those trucks necessary to shuttle supplies to each regiment during a twenty-four hour lift rather than all at once.

Rifle units were not motorized! Each division, instead, contained six truck companies for leapfrogging them forward. He also encouraged infantry to ride supporting tanks or borrowed artillery trucks for short hops.

These concepts were only partially successful in combat. The divisions clambered for additional tank, AA, TD, and engineer support virtually all the time. Switching units between divisions often caused confusion and inefficiency. There were procedural and personality clashes between officers not used to each other's way of doing things.

Once a good working relationship was established, prying effective support units away from a satisfied division commander was 'difficult'. Higher headquarters tended to 'let things be' whenever possible to allow for mutual trust to develop.

A typical U.S. division in France in 1944 had attached tanks, TD's, automatic AA weapons, corps engineer units, 4.2" mortars, transportation, and logistical support units from corps and army levels. In the end, the triangular division was larger, more rigid, and more motorized than McNair envisioned.

These augmented divisions ended up with the mobility of a motorized division and often the firepower of an under strength armored division. Compare this to the German forces they faced and there is little doubt they presented a formidable opponent.

During the same period, the armored divisions underwent many more changes than the infantry divisions. When Jacob Devers; became chief of the Armored Force in August 1941 he broke up the rigid U.S. armored division organization in favor of two 'Combat Commands'. The CCA and CCB headquarters could control any mixture of forces aimed at a particular mission. In this way the Americans institutionalized the Kampfgruppe concept the Germans achieved through improvisation.

This was the last section of my "Tactical Notebook" series on the development of mechanized warfare. Anyone who wishes to study this further should consult the U.S. Army Command and General Staff College publications available through Fort Leavenworth, Kansas 66027, a used bookstore near you, or by pestering a retiree like me!

More Combined Arms

Part I: England
Part II: Germany
Part III: Soviet Russia
Part IV: USA