The Office of Strategic Services was formed on June 13th, 1942. Prior to this, intelligence had been gathered by disparate groups such as the US Army or the US Navy for specific military purposes, and was largely uncoordinated between agencies. At the suggestion of British/Canadian spy William Stephenson, President Franklin D Roosevelt established the OSS to provide intelligence information to the Joint Chiefs of Staff.
During the war, the OSS provided facts to policy makers in America, but still had no control over a great deal of foreign intelligence gathering, which was controlled by the FBI; the Army and the Navy also retained control over their own intelligence-gathering operations. Beginning in 1943 and continuing to the end of the war, members of the OSS were involved in recruiting and training various indigenous forces in Axis-occupied areas, such as the Kuomintang in China and Burma, Mao Zedong's Red Army in China and the Viet Minh in French Indochina. They were also involved in propaganda and espionage, as well as post-war planning.
In 1943 they began operating out of Istanbul, Turkey, establishing chains of intelligence throughout Europe, allowing them to make contact with anti-fascist groups throughout the Axis-controlled territories. They conducted espionage against Nazi Germany, recruiting and handling one of the most important spies of the war, the diplomat Fritz Kolbe. The largest chain, the so-called Dogwood-chain, was based on a Czechoslovakian engineer and businessman who became known as Dogwood, was established in 1943. In 1944 the Dogwood-chain was shut down after it was determined to be passing on incorrect information.
On October 1st, 1945 the operations of the OSS were split between the Department of State and the Department of War. This marked the end of the OSS, which was eventually reformed as the CIA.
A great deal of OSS operations were kept secret. They operated training camps at Prince William Forest Park in Virginia; Catoctin Mountain Park in Maryland; Toyon Bay, in California; Congressional County Club, the main training camp, also in Maryland; and Camp X, in Ontario. The number and identities of OSS personnel was kept secret until 2008, when documents were released revealing that it had 24,000 employees at the height of its power, including several famous people such as celebrity chef Julia Child, baseball player Moe Berg and director John Ford, among others.