The History Division is supported by two reserve organizations, together which form the Field History Branch of the History Division (HD). While their missions are similar, each is composed of a different category of reservists: first, the IMA Detachment, is composed of members of the Selected Marine Corps Reserve (SMCR), who attend drill once a month, or in back-to-back “stacked” drills, and Annual Training Duty for two weeks each year. Members of the IMA Det are at a higher level of training and readiness for mobilization and deployment. The second reserve organization, MTU DC-7, is composed of members of the Individual Ready Reserve (IRR) who do not meet regularly for drill, but who may complete up to 27 days of Reserve Counterpart Training (RCT) orders per year; additionally, MTU members can earn points without pay throughout the year assisting HD with various tasks. Members of both organizations are also available for mobilization to complete the History Division's wartime task, overseas as well as at HD’s Quantico location. The administration of both organizations is the responsibility of the History Division Director, the IMA OIC, and the MTU OIC--assisted by the Quantico Reserve Support Unit (RSU).
The mission of the Field History Branch is to assist the Director of Marine Corps History Division in his responsibilities to "record, preserve, and disseminate the cumulative, operational, and institutional experience of the Marine Corps." The detachment accomplishes this task through a variety of activities: (1) collection of oral history, documentary, visual (photography and combat art), and artifactual history of the Marine Corps, accomplished by deployed field historians and combat artists with Marine Corps operational forces and joint service commands; (2) performing research and writing on historical subjects as assigned by the director; (3) creating artworks reflective of Marine Corps operations and historical subjects as assigned by the Director; and, (4) cataloging documents and other materials into the History Division archives.