2nd Brigade, 78th Division (Training Support)

The 2nd Brigade, 78th Division (Training Support) was inactivated in 2009 as part of the reorganization of the 78th Division (Training Support) to the 78th Training Brigade.

2nd Brigade, 78th Division (Training Support) provided training assistance, support, and evaluation to priority Reserve Component units and all other units within capabilities. It synchronized training support within its area of responsibility in order to enhance individual and unit readiness to meet directed mobilization and/or wartime requirements. On order, it would activate or augment Mobilization Assistance Teams to assist installation commanders in post-mobilization training and validation of mobilized units for deployment. It would also, on order, deploy a Defense Coordinating Officer and/or a Defense Coordinating Element to coordinate military support to civilian authorities during federal disaster response operations.

The 2nd Brigade, 78th Division (Training Support) was first constituted on 5 August 1917 in the National Army as the 303rd Ammunition Train and assigned to the 78th Division. It was organized in December 1917 at Camp Dix, New Jersey. The unit participated in 3 campaigns during the Great War as part of the 78th Division: St. Mihiel, Meuse-Argonne, and Lorraine 1918. After the end of the war, the unit was demobilized on 23 May 1919 at Camp Dix, New Jersey.

The unit was reconstituted on 23 October 1936 in the Organized Reserves. It was concurrently consolidated with the 303rd Ammunition Train (first organized in November 1921 in the Organized Reserves with Headquarters at Jersey City, New Jersey) and the consolidated unit was designated as the 303rd Ammunition Train, an element of the 78th Division.

The unit was converted and redesignated on 20 February 1942 as the 903rd Field Artillery Battalion, and remained assigned to the 78th Division (later redesignated as the 78th Infantry Division). The Battalion was ordered into active military service on 15 August 1942 and reorganized at Camp Butner, North Carolina. Deployed to the European Theater of Operations during World War II, the Battalion participated in 3 campaigns: Rhineland, Ardennes-Alsace, and Central Europe. After the end of the war, the Battalion was inactivated between 22 and 25 April 1946 at Camp Kilmer, New Jersey.

The unit was reactivated on 21 February 1947 at Elizabeth, New Jersey. The location of the Battalion's Headquarters changed on 18 October 1950 to New Brunswick, New Jersey. During this period, the Organized Reserves was redesignated on 25 March 1948 as the Organized Reserve Corps, which in turn was redesignated on 9 July 1952 as the Army Reserve. The unit remained a part of this organization throughout the redesignations. On 23 April 1957, the location of the Battalion's Headquarters changed to Nixon, New Jersey. The Battalion was disbanded entirely on 1 May 1959 at Nixon, New Jersey.

Headquarters, 903rd Field Artillery Battalion was reconstituted 24 November 1967 in the Army Reserve as Headquarters, 2nd Brigade, 78th Division (Training) and activated on 31 January 1968 at Lodi, New Jersey.

The unit was ordered on 25 January 1991 into active military service at Lodi, New Jersey. It was released on 31 March 1991 from active military service and reverted to reserve status. The Brigade's location changed on 1 February 1993 to Fort Dix, New Jersey and it was reorganized and redesignated on 1 October 1993 as Headquarters, 2d Brigade, 78th Division (Exercise).

The unit was reorganized and redesignated again on 17 October 1999 as Headquarters, 2nd Brigade, 78th Division (Training Support) and allotted to the Regular Army at Fort Drum, New York. At that time, the 174th Infantry Brigade (Training Support) was inactivated and reflagged as the 2nd Brigade, 78th Division (Training Support). The change, part of the Training Support XXI program, restructured active component support to reserve component units, reflecting the Army's increased reliance on reserve forces, transitioning to a fully integrated multi-component organization.