Was it necessary to drop the atom bombs to defeat Japan?

On the night of 9-10 March 1945, 279 giant US B-29 Superfortress bombers launched a new type of raid on the Japanese capital Tokyo. They dropped 496,000 small six-pound M-69 incendiaries which, unlike those used in Europe, each contained a small amount of a highly flammable jelly known as ‘napalm’ that had been developed earlier in the war by a Harvard scientist, Louis Fieser. Tokyo’s Air Raid Precautions were very poor. There were few shelters and limited anti-aircraft batteries. Thousands of fires were started in some of the most densely populated areas of the city. The small wooden houses were soon engulfed in a major firestorm that spread rapidly from roof to roof and building t