October 1, 1945, the Office of Strategic Services (OSS) closed its doors. Fortunately, Assistant Secretary of War John J. McCloy ordered OSS’s Deputy Director for Intelligence, Brig. Gen. John Magruder, to preserve the SI and X-2 branches “as a going operation” in a new office that McCloy dubbed the “Strategic Services Unit” (SSU).
Within two years the President and the Congress found a new home for the personnel and assets saved in SSU under Col. William W. Quinn. They went to a new organization called the Central Intelligence Group (CIG) until the National Security Act of 1947 turned CIG into the Central Intelligence Agency, to perform many of the missions that General Donovan had advocated for his proposed peacetime intelligence service.
Although CIA differed from OSS in important ways (which is why Truman endorsed it and not OSS), Donovan and his office deserve credit as forefathers of the Agency.