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This is a partial list of agencies under the United States Department of Defense (DoD) which was formerly and shortly known as the National Military Establishment. Its main responsibilities are to control the Armed Forces of the United States. It is headed by the Secretary of Defense.
The department was established in 1947 and is divided into three major Departments—the Department of the Army, Navy and Air Force, as well as a number of other component organizations.
Field activities are DoD agencies which "perform a supply or service activity common to more than one military department".[1]
Army Commands (MACOMs)
Major Commands (MAJCOMs)
Field Commands
The United States has eleven Combatant Commands (COCOM); seven Geographical Combatant Commands (GCC) & four Functional Combatant Commands (FCC).
GCCs:
FCCs:
Most information on this list was taken from Government Information. Some was taken from USA.gov.