Operational Group Command
Operational Group Command, was a branch of the Office of Strategic Services during World War II that specialized in clandestine and covert operations, combat search and rescue POWs and allies spies captured in areas occupied by the Axis powers, commando style raids on key targets, frontline military intelligence gathering, guerrilla warfare, independent operations against designated Axis powers targets, maneuver warfare, providing military assistance to resistance movement groups in areas occupied by the Axis powers, special reconnaissance, and support military strategy and tactical operational plans.
The original A Teams of United States Army Special Forces, Operational Detachment Alpha, are modeled after the successes of Operational Group Command and its groups.
William Donovan and Millard Preston Goodfellow were concerned with creating guerrilla commando units within SA/G as early as December 1941.
Operational Group Command was made up of Operational Groups, which were originally created on 23 December 1942 as a division within the OSS Special Operations Branch, before achieving Branch status.
One key distinction between SO units and the OGs might be the fact that OGs were always dressed in military uniform, and were deployed within the military command structure, whereas SO units were civilian units, often assuming cover identities.