United States Tank Corps

Tank Corps of the American Expeditionary Forces
Lieutenant Colonel George Patton, pictured here in France, in the summer of 1918, standing in front of a French Renault tank.
Active	either 22 December 1917 or 26 January 1918 to 11 November 1918
Country	United States
Branch	United States Army
Part of	the American Expeditionary Force
Commanders
Commander	Samuel Rockenbach

The Tank Corps of the American Expeditionary Forces was the mechanized unit that engaged in tank warfare for the American Expeditionary Force (AEF) on the Western Front during World War I.

Brigadier General Samuel D. Rockenbach, as the Chief of Tank Corps for the American Expeditionary Forces under Pershing, organized, trained, equipped and then deployed the first American tank units to the Western Front of 1918 Europe. An initial plan for 2,000 light Renault FT tanks and 200 heavy British Mark VI tanks was changed to 20 battalions of 77 light tanks each and 10 battalions of 45 heavy tanks each. A total of eight heavy battalions (the 301st to 308th) and 21 light battalions (the 326th to 346th) were raised, but only four (the 301st, 331st, 344th and 345th) saw combat.

Captain George S. Patton, the first officer assigned to the unit, set up a light tank school at Bourg, France, starting on November 10, 1917. In the first half of 1918, the 326th and 327th Tank Battalions were organized at Patton's school, while the 301st Heavy Tank Battalion was raised at Camp Meade, Maryland, USA and transported to the British Tank Schools at Bovington Camp in southern England, for training.

The 326th (under the command of Sereno E. Brett) and 327th Tank Battalions (later renamed the 344th and 345th and organized into the 304th Tank Brigade, commanded by Patton), were the first into combat, beginning with the Battle of St. Mihiel (as part of the US IV Corps) on 12 September 1918, followed by the Meuse-Argonne Offensive (as part of the US V Corps) on 26 September. Major Brett assumed command of the 304th after Patton was injured during the St. Mihiel Offensive. The small French Renault FT tanks they were equipped with found the going hard and many were lost or ran out of fuel crossing the battlefield – the Germans, forewarned, had largely retreated from the salient.