The 12th Army Group was the largest and most powerful American formation ever to take to the field. It controlled the majority of American forces on the western front in 1944 and 1945. It was commanded by General Omar Bradley.

12th Army Group occupied the right flank of the Allied lines in Normandy, and the centre of the Allied line after 6th Army Group came into the line. At its peak it controlled four field armies, US First Army, US Third Army, US Ninth Army and US Fifteenth Army.