278th Armored Cavalry Regiment of 2004: The Last National Guard ACR

In 2004, the 278th Armored Cavalry Regiment was a unit wholly of the Tennessee Army National Guard. Its doctrinal mission was to conduct reconnaissance, security, and economy of force missions in support of V Corps, or act as an armored task force when reinforced. At the time, the active force had 3d ACR (III Corps), 2d ACR(L) (XVIII Airborne Corps) and 11th ACR (NTC OPFOR). This made the 278th one of only a handful true ACRs and the last ACR in the National Guard.

The ACR was one of the coolest unit types in U.S. Army history. Like other ACRs, the 278th was a tactically self-contained unit. Armored Cavalry Squadrons had their own self-propelled howitzer battery and the regiment had a whole Regimental Aviation Squadron with 6 troops (companies) of scout, attack, and utility helicopters. Because the premiere mission of the ACR was the Corps Cover (definitionally requiring the ACR to operate independently from the corps to engage and destroy enemy forces far ahead), it needed these assets to afford adequate independence and allow it to perform all manner of ground and aerial reconnaissance. It also had an organic support squadron (not yet a thing in the pre-Modular Force maneuver brigades), and air defense, CBRN, engineer, and military intelligence companies. Further, during a Corps cover mission, they'd expect to be reinforced with corps assets, such as MLRS.

The 278th ACR’s armories were predominantly spread throughout Middle and East Tennessee, with only a few detachments posted to Jackson in West Tennessee. The stations listed here are based on this website from 2004. By 2006 with GWOT well underway the 278th ACR was converted into a Heavy Brigade Combat Team (later renamed Armored Brigade Combat Teams), although they kept their ACR designation. Now, as of 2025-26, they are in the process of converting into a Mobile Brigade Combat Team (MBCT) equipped with Infantry Squad Vehicles.