THE UNITED STATES ARMY IN WORLD WAR II
by Rich Anderson
 
Doctrine and Training

U.S. Army doctrine, as developed during the prewar and early-war Army expansion, emphasized mobility and combined-arms in both attack and defense. Mobility was achieved by developing reliable, robust armored and soft-skin vehicles. Unfortunately, in the case of tanks and tank destroyers, thickness of armor was sacrificed in the interest of mobility to the detriment of U.S. Army armored vehicles in tank-versus-tank-combat. This flaw was exacerbated by one of General McNair's fundamental beliefs (later proved to have been fundamentally unsound) that the armored division would not be required to engage and destroy enemy armored formations since that would be the task of the tank destroyers. Rather he visualized the armor divisions as a cavalry force to exploit gaps opened in the enemy lines by the tank-supported infantry divisions. The major flaw in this concept was that the lightly armored tank destroyers proved regularly that they were unable to engage and destroy enemy armor when it attacked in mass, even when the tank destroyers were deployed in concealed defensive positions. While the tank destroyers on defense were often able to delay or blunt an armored attack, they could rarely defeat them. Thus, instead of operating in an independent antiarmor role, the tank destroyers were semi-permanently attached to infantry and armored divisions, while armored divisions were forced to take up defensive as well as offensive missions, a role for which they were not well designed (since they lacked sufficient infantry). 

Another fundamental doctrinal belief espoused by General McNair was that pooling and standardization in the organization of the combat arms would facilitate the cross-attachment of units into combined-arms teams. Here too the realities of wartime experience proved to be somewhat different. It was discovered that the close cooperation required of combined-arms teams required extensive training and combat experience to be effective. Unfortunately, the infantry division training program involved extensive practice in infantry-artillery coordination, but no training in armor-infantry-artillery coordination. In most cases the first armor-infantry-artillery combined arms operation for an infantry division was conducted in combat and not in training. Furthermore, pooling meant that most of the infantry divisions did not have tank or tank destroyer battalions attached until after they had entered combat. The result was predictable; the introduction of "green" infantry divisions into combat often resulted in disaster rather than success. Eventually combat experience and unnecessary casualties forced changes in the emphasis in the training regimen, but problems continued to persist until the end of the war.

Finally, the basic tenant of U.S. Army Infantry doctrine was based on fire and maneuver at the squad level. The M1 Garand semi-automatic rifle and the BAR provided firepower at the squad level. However, in the ETO it was found that these were unequal to the job of suppressing the firepower of the German squad, which was equipped with the formidable MG42 light machine gun. Over and over the advance of American infantry faltered when encountering this German weapon which was capable of firing up to 1,100 round-per-minute (the distinctive sustained roar of this machine gun gave rise to common GI epithet applied to it, "burp gun"). Worse, German small arms utilized ammunition which gave off little flash or smoke. American ammunition had a pronounced signature, giving off a distinctive puff of blue smoke and an intense flash. The result was that German infantry could fire with a good chance of not revealing their position, American infantry could not. All American ammunition had this characteristic to a degree; tank and artillery rounds also gave off a prominent flash.