The 21st Cavalry Division was a division of the United States Army National Guard located in the north eastern United States. The division was composed of personnel from the New York, New Jersey, Pennsylvania and Rhode Island Army National Guards.
The division was created from the perceived need for additional cavalry units after the First World War. It numbered in succession of the Regular Army Divisions, which were not all active at its creation.
The Division was constituted in 1921 and assigned to the First Army. Not all authorized units were active during the Division's lifetime. The Division did not participate in the First Army maneuvers in 1935, 1939, and 1940. The 21st was inactivated on 1 October 1940 and disbanded on 1 November 1940.
Headquarters, New York City, New YorkHeadquarters Troop, West New Brighton, New York51st Cavalry Brigade, New York[1]Headquarters Troop, Staten Island, New York101st Cavalry Regiment (New York National Guard), Brooklyn, New York[2]121st Cavalry Regiment (New York National Guard), Rochester, New York[3]59th Cavalry Brigade, Newark, New JerseyHeadquarters Troop, Newark, New Jersey102d Cavalry Regiment (New Jersey National Guard), Newark, New Jersey[4]110th Cavalry Regiment (Massachusetts National Guard), Boston, Massachusetts[5]112th Field Artillery Regiment, Trenton, New Jersey[6]Headquarters Special Troops, West New Brighton, New York21st Signal Troop, West New Brighton, New York125th Ordnance Company, (Medium), Connecticut21st Tank Company (Light), New York21st Reconnaissance Squadron, Boston, Massachusetts125th Engineer Squadron, New York121st Medical Squadron, New York121st Quartermaster Squadron, Boston, Massachusetts
