The 4th Cavalry Brigade is an AC/RC unit based at Fort Knox, Kentucky. The unit is responsible for training selected United States Army Reserve & National Guard units that are based East of the Mississippi River. The brigade was originally formed as an element of the 2nd Cavalry Division but was inactivated after the division was broken up. The unit was formerly designated as 4th Brigade, 85th Division. The brigade is a subordinate unit of the 1st Army.
The 4th Cavalry Brigade is a Multi-Functional Training Brigade (MFTB) assigned to the 85th Support Command. Like all formations of the 85th Support Command, the brigade is not a combat formation, but instead trains Army Reserve and Army National Guard units preparing for deployment. As of January 2026, the brigade consists of a Headquarters and Headquarters Company, five active duty battalions, and five reserve battalions.
The brigade's four training support battalions and logistical support battalion are Army Reserve formations.
Constituted 25 August 1942 in the Army of the United States as Headquarters, 4th Tank Destroyer Group
Activated 1 September 1942 at Camp Hood, Texas
Inactivated 26 October 1945 at Fort Jackson, South Carolina
Disbanded 5 August 1952
Reconstituted 24 October 1997 in the Regular Army as Headquarters, 4th Cavalry Brigade, and activated at Fort Knox, Kentucky
Inactivated 16 October 1999 at Fort Knox, Kentucky
Activated 1 December 2006 at Fort Knox, Kentucky