First Army Division East is a division of the First United States Army. With its new role, the First Army developed two subordinate multi-component headquarters – one division to support the eastern United States and the other to support the western United States. First Army Division West was activated at Fort Carson, Colorado, and later moved to Fort Hood, Texas. First Army Division East was activated on 7 March 2007 at Fort George G. Meade, Maryland, and later moved to Fort Knox, Kentucky.

First Army is the oldest and longest-established field army of the United States Army. It served as a theater army, having seen service in both World War I and World War II, and supplied the US army with soldiers and equipment during the Korean War and the Vietnam War under some of the most famous and distinguished officers of the U.S. Army. It now serves as a mobilization, readiness and training command.