1) Forcing unconditional surrender on Germany and Japan, whereby virtually every citizen of those countries was convinced that they had lost the war and that resorting to armed struggle for their goals was a complete failure for Germany and Japan, and,
2) A lengthy occupation in those countries that accomplished many things, including the "de-nazification" of educational system.
The prospects Palestinians are faced with, as proven by the West Bank, are very bleak, making any peace very very unstable.