Did the US have to use nuclear weapons to achieve Japan's unconditional surrender?
In 1945, at the height of the Second World War, two nuclear weapons were launched from the United States into Japan. Shortly after the bombings, Japan surrendered, initiating a sequence of events that led to the end of the war. Despite the strong causal relationship that has been drawn between the dropping of Fat Man and Little Boy on Hiroshima and Nagasaki respectively, historians still argue as to whether or not the use of nuclear weapons was absolutely necessary.
Proponents of the use of nukes make the case that the show of brute force and unmatched military power of the USA pushed Japan to surrender out of fear. They also argue that the previous attempts at conventional warfare had not worked. They also make the case that using nuclear weapons allowed Japan to surrender more easily because it allowed them to save face while doing so.
Opponents of the bombings are of the view that the use of nuclear weapons, while correlated to the surrender, was not absolutely essential. Japan had already planned to surrender and was open to negotiations. Additionally, the fact that the Soviet Union joined the war made Japan's surrender inevitable. For these reasons, they make the case that the use of nuclear weapons was unnecessary.
If we could turn back time, would it be better to not use nuclear weapons in World War II? Can we say with absolute certainty that the war would have ended without them? Most importantly, if the use of nukes shortened the war, could that ever justify the horrors it caused?