And here is a very concise article about why the bombing was not (strategically) necessary:
http://www.doug-long.com/hiroshim.htm
Quote:
And so from November 1944 onward, Japan was the subject of numerous large-scale B-29 non-nuclear bombing raids (Robert Butow, Japan's Decision To Surrender, pg. 41). When Air Force chief General Hap Arnold asked in June 1945 when the war was going to end, the commander of the B-29 raids, General Curtis LeMay, told him September or October 1945, because by then they would have run out of industrial targets to bomb (Sherry, pg. 300 & 410(143n)).
While Japan was being bombarded from the sky, a Naval blockade was strangling Japan's ability to import oil and other vital materials and its ability to produce war materials (Barton Bernstein, ed., The Atomic Bomb, pg. 54). Admiral William Leahy, the Chief of Staff to President Roosevelt and then to President Truman, wrote, "By the beginning of September [1944], Japan was almost completely defeated through a practically complete sea and air blockade." (William Leahy, I Was There,