I travelled to Hiroshima this year, and after the trip, it perked my interest and I read abit more about it when I came back, I came across the points that Wind30 pointed out. The main one was that Japan was ready to surrender, but what the allies wanted was an unconditional surrender. Even with the surrender, one of the condition the Japanese asked for was for the Emperor to remain in power as before, but the allies was not willing to compromise with that or any conditions. If you are going to Japan/Tokyo, I suggest you visit to the Yasukuni shrine, there is a WAR museum there. They give their reasons for the war and their version of it. They claimed that they were forced to attack America due to some policies/situation of that time. Many people would balk at the reasons/stories that you can read there, but rememeber history is written by the victor, the truth is probably in the middle.