Actually on the 6th and 9th, but...
According to Admiral William D. Leahy, Chair of the Joint Chiefs of Staff and President Truman's Chief of Staff: "The Japanese were already defeated and ready to surrender because of the effective sea blockade and the successful bombing with conventional weapons... In being the first to use it [the atomic bomb], we had adopted an ethical standard common to the barbarians of the Dark Ages."
"Japan was at that very moment seeking some way to surrender with a minimum loss of 'face'... It wasn't necessary to hit them with that awful thing." (General Dwight David Eisenhower Commander in Chief of Allied Forces in Europe).
"It would be a mistake to suppose that the fate of Japan was settled by the atomic bomb. Her defeat was certain before the first bomb fell." (UK Prime Minister Winston Churchill.)
"Certainly prior to 31 December 1945... Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war and even if no invasion had been planned or contemplated." (US Strategic Bombing Survey, 1946.)
"General Curtis LeMay: 'The war would have been over in two weeks without the Russians entering and without the atomic bomb.'
Field Marshal Montgomery ( Commander of all UK Forces in Europe) wrote in his History of Warfare: It was unnecessary to drop the two atom bombs on Japan in August 1945, and I cannot think it was right to do so .... the dropping of the bombs was a major political blunder and is a prime example of the declining standards of the conduct of modern war.
Truman's Chief of Staff, Admiral Leahy, wrote: It is my opinion that the use of this barbarous weapon at Hiroshima and Nagasaki was of no material assistance in our war against Japan. The Japanese were already defeated and ready to surrender because of the effective blockade and the successful bombing with conventional weapons ... In being the first to use it, we adopted an ethical standard common to the Dark Ages. I was not taught to make war in this fashion, and wars cannot be won by destroying women and children.
"The dropping of the first atomic bomb was also an act of pure terrorism. It fulfilled no military purpose of any kind. Belatedly it has been disclosed that seven months before it was dropped, in January 1945, President Roosevelt received via General MacArthur's headquarters an offer by the Japanese Government to surrender on terms virtually identical to those accepted by the United States after the dropping of the bomb: in July 1945, as we now know, Roosevelt's successor, President Truman, discussed with Stalin at Bebelsberg the Japanese offer to surrender....The Japanese people were to be enlisted as human guinea-pigs for a scientific experiment."
- F.J.P Veale, Advance To Barbarism: The Development Of Total Warfare From Serajevo To Hiroshima (California: Institute for Historical Review, 1979), pp.352-53.