This Army Techniques Publication (ATP) manual provides basic doctrinal discussion on the organization and operations of the Army Field Support Brigade. The primary target audience for this field manual includes: Headquarters Department of the Army, Army commands, theater armies, direct reporting units, and supported units at all levels. ATP 4-91 applies to the Active Army, Army National Guard (ARNG)/Army National Guard of the United States (ARNGUS) and the US Army Reserve (USAR) unless otherwise stated.