Why did American generals fear invading the Japanese mainland?

Answer 1

Japanese military leaders were interviewed after their surrender in 1945 about this and the general reply was that the US is the most armed and aggressive society in the world. It would have been foolish for them to even try.

Answer 2

According to my Father and Uncle, who were in the War in the Pacific, Truman didn't want to invade Japan because of the awful loss of life that would result. The Japanese at that time regarded their Emperor as a Divinity (direct descendent of the marriage of the Sun Goddess with a human), and they would fight to the last person to protect him. Also, Japan had been very insular before the War, and did Not want outsiders in their country. Frankly, Truman believed that every last Japanese man, woman, and child would die before surrendering. Truman thought that, even though the A-bomb would kill millions, it would shock the Japanese into realizing that continued fighting would mean the end of the Japanese people. Even with that, MacArthur had to agree not to try the Emperor, or take away his throne, before Japan would surrender. That's why the Emperor of Japan was the only Axis leader to not only survive WWII, but who kept his crown, was never tried for War Crimes, and lived long after the War ended. And that's why the Allies never invaded the Japanese homeland. Fear of the Loss of Allied lives, surely, but also fear of the loss of a People and a great Nation. That's why my relatives said. - and they were pretty high up in the chain of command. Of course they couldn't read either Truman or MacArthur's minds, but it sounds reasonable. I don't suppose we'll ever know All of it.

Answer 3

Because while it was highly unlikely, the possibility did exist that an attempt might be made in an effort to wreak havoc and prolong the War.