Detachment 404 was formed to help coordinate intelligence collection and operations of covert organizations like the OSS and British Special Operations Executive (SOE) in the Far East. Detachment 404 also recruited indigenous personnel from enemy-controlled areas to be reinserted as trained agents via submarines. In addition, it established coast watchers to gather meteorological and topographical shoreline data, record tide tables, report on Japanese shipping, and arrange for the rescue of downed Allied pilots. Located in what is now Sri Lanka, Detachment 404 worked with Admiral Lord Louis Mountbatten’s predominately-British Southeast Asia Command (SEAC).
Detachment 404’s area of responsibility was huge—the Andaman Islands, India, Indonesia, Malaya, Sumatra, Thailand, and parts of Burma and French Indo-China (Vietnam). Thailand, an occupied and unwilling Japanese ally, offered the most potential for OSS operations. High-ranking Thai politicians enabled Special Operations (SO) and Secret Intelligence (SI) teams to infiltrate in late 1944. These teams collected volumes of intelligence and trained a guerrilla force, but the war ended before they could be employed The OSS support generated such positive feelings towards the U.S. that President Dwight D. Eisenhower appointed William J. Donovan to be his Ambassador to Thailand in 1953.
The Arakan Field Unit (AFU) of Detachment 404 was a 175-man element that contained SI personnel, Operational Groups (OG) and the Maritime Unit (MU). It was employed along the Burma Coast to assist the XV Indian Corps of the British XIV Army. In February 1945, Detachment 101 assumed operational control of the AFU. OG and MU personnel jointly conducted reconnaissance missions along the Arakan coast and up its numerous inlets and rivers. While helping liberate Rangoon, AFU elements collected considerable intelligence. These accomplishments in a highly political environment demonstrated how the OSS persevered and adapted to accomplish all missions.