They were the dogfaces.

Dogfaces is the definitive roleplaying sourcebook for U.S. ground forces in World War II. Whether it's storming the beaches of Normandy, outdueling German tanks in the Ardennes, or retaking the Pacific island by island, the infantry, armor, and artillerymen of the U.S. Army and Marines were the backbone of the Allied war effort. With the attention to detail and historical accuracy that GURPS is known for, Dogfaces gives you all the information you need for roleplaying this vital part of mankind's greatest conflict.