TheTank Corps of the American Expeditionary Forces was themechanized unit that engaged intank warfare for theAmerican Expeditionary Forces (AEF) on theWestern Front duringWorld War I.

Tank Corps of the American Expeditionary Forces
Lieutenant ColonelGeorge S. Patton, pictured here in France, in the summer of 1918, standing in front of a FrenchRenault tank.
Active	22 December 1917[1] to 1920.
Country	United States
Branch	United States Army
Part of	theAmerican Expeditionary Forces
Commanders
Commander	Samuel Rockenbach[2]

Brigadier GeneralSamuel 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.^[3] An initial plan for 2,000 lightRenault FT tanks and 200 heavy BritishMark VI tanks was changed to 20 battalions of 77 light tanks each and 10 battalions of 45 heavy tanks each.^[4] A total of eight heavy battalions (the301st to 308th) and 21 light battalions (the 326th to 346th) were raised, but only four (the 301st, 331st, 344th and 345th) saw combat.^[5]

CaptainGeorge S. Patton, the first officer assigned to the unit, set up a light tank school atBourg, France, starting on 10 November 1917.^[1][6] 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 atCamp Meade,Maryland, USA and transported to the British Tank School atBovington Camp in southern England, for training.^[1]

The 326th (under the command ofSereno E. Brett) and 327th Tank Battalions (later renamed the 344th and 345th^[7] and organized into the 304th Tank Brigade, commanded by Patton), were the first into combat, beginning with theBattle of Saint-Mihiel as part of theUS IV Corps on 12 September 1918. The small FrenchRenault 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.^[8] The tanks then took part in theMeuse–Argonne offensive as part of theUS V Corps on 26 September.^[5][6][9] Major Brett assumed command of the 304th after Patton was injured on 26 September, the first day of the Meuse-Argonne Offensive near Cheppy, France.^[10]

During the war, two members of the Tank Corps (both from the 344th Battalion) were awarded theMedal of Honor;Donald M. Call andHarold W. Roberts.^[11][12]

When the fighting ended on November 11, 1918, the AEF Tank Corps and the units in the United States had about 20,000 men.^[13] The AEF Tank Corps was redeployed after the armistice, with the remaining tank corps personnel transferred back to theUnited States. TheTank Corps, which formed part of theNational Army, was formally disbanded in 1920, when the National Army was demobilized and consolidated into theRegular Army. After transfer toCamp Meade, Maryland, the 304th and 305th Tank Brigades were consolidated and redesignated several times, together eventually forming the 1st Tank Regiment on 1 September 1929. This unit was again reorganized and redesignated as the 66th Infantry Regiment (Light Tanks) on 25 October 1932, and remains in active service as of 2024. Now known as the66th Armor Regiment, it is the oldest armored unit in the modern US Army.

• AK-Interactive S.L. (2014).WWI: The First Mechanized War. AK-Interactive S.L.- Total pages: 172