The Atomic Bomb: the Only Order to Actually Use Nuclear Weapons, 25 July 1945

JF Ptak Science Books LLC 

Here are the two basic documents which prepared the actual use of atomic weapons against Japanese targets (written 22 July and 25 July, respectively).    The first was prepared by Colonel John Stone for his superior General of the Army Air Forces Henry H. Hap Arnold, initiated by General George Marshall through General Thomas Handy—updating Arnold on the progress at the Potsdam Conference from which he (Stone)  had just returned.  The next is the only actual signed-off document authorizing the use of nuclear weapons, and comes under the direction of George Marshall’s directive to General Handy:  basically relating that the P{resident had authorized Secretary Stimson who had authorized Marshall to authorize Handy to authorize General Carl Spaatz (Commanding General, U.S. Army Strategic Air Force) to use the weapon. Spaatz is also directed to deliver a copy of the order (“personally”, that is, by hand)  to General MacArthur and Admiral Nimitz.
Source: The National Security Archive