Fort Myer, VA is currently home to the First Battle Group, Third Infantry.
The Third Cavalry (HQ, 2nd, 3rd Squads) was at Fort Sam Houston, San Antonio, with 1st Squad at Brownsville, Texas, according to the "Army List and Directory" of June 1915, and May 1917. In the July 1920 "Army List and Directory", the Third Squadron, Third Calvary was at Fort Myer, and the First and Second Squadrons were at Fort Ethan Allen, VT.
Hope this helps.
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