You are encouraged to read deeper about the end of WWII. If anyone sacrificed the people of Hiroshima, it was the Japanese Imperialist Government that refused to surrender despite the obvious obliteration of their conventional forces.
To make it brief, every single landmass occupied by Japanese forces and civilians offered fierce resistance/guerilla warfare to invading/liberating forces. Additionally, as another commenter has noted, the Japanese military had significantly increased their numbers to a staggering 6 million troops towards the end. The death toll projections, based on the above, for a mass land invasion of Japan were many factors greater than the life cost of both Hiroshima and Nagasaki combined - many, many factors greater.
The Japanese government did not just refuse to surrender, but continued to wage war. This meant either a land invasion, or some alternative were necessary to compel the government into surrender.
Dropping the second nuclear bomb accomplished this goal - particularly when accompanied by the (empty) threat of dropping many more until surrender.
It also should be noted both Hiroshima and Nagasaki were central to the Japanese war economy/machine and were not simply civilian population centers. Regardless, the loss of life directly from the bombings and indirectly from the aftermath is still calculated to have been significantly less than the loss of life had a ground invasion been waged.
To make it brief, every single landmass occupied by Japanese forces and civilians offered fierce resistance/guerilla warfare to invading/liberating forces. Additionally, as another commenter has noted, the Japanese military had significantly increased their numbers to a staggering 6 million troops towards the end. The death toll projections, based on the above, for a mass land invasion of Japan were many factors greater than the life cost of both Hiroshima and Nagasaki combined - many, many factors greater.
The Japanese government did not just refuse to surrender, but continued to wage war. This meant either a land invasion, or some alternative were necessary to compel the government into surrender.
Dropping the second nuclear bomb accomplished this goal - particularly when accompanied by the (empty) threat of dropping many more until surrender.
It also should be noted both Hiroshima and Nagasaki were central to the Japanese war economy/machine and were not simply civilian population centers. Regardless, the loss of life directly from the bombings and indirectly from the aftermath is still calculated to have been significantly less than the loss of life had a ground invasion been waged.