US Army Ranks and Unit Structure,
1917–1918

During World War I, US Army ranks and units were organized as follows:

SOLDIER

SQUAD: 9 to 17 soldiers, usually led by a corporal or sergeant

PLATOON: 4 to 5 squads, 60 soldiers, usually led by a lieutenant

COMPANY: 4 platoons, 250 soldiers, usually commanded by a captain

BATTALION: 4 companies, 1,030 soldiers, usually commanded by a major or lieutenant colonel

REGIMENT: 3 battalions, plus a machine-gun company, approximately 3,700 soldiers, commanded by a colonel

BRIGADE: 2 infantry regiments, plus a machine-gun battalion, approximately 8,400 soldiers, commanded by a brigadier general

DIVISION: 2 brigades, plus a field artillery brigade, an engineers regiment, a machine-gun battalion, and a signal corps company, totaling approximately 28,000 soldiers, commanded by a major general

CORPS: 2 to 6 divisions

ARMY: 3 to 5 corps