World War II was settled by the Allies completely defeating the Axis Powers. By the middle of the war, the Allies had all agreed that they would not allow Germany or Japan to push for any sort of negotiated peace. Instead, they announced that they would accept nothing less than unconditional surrender from both countries. This is what they got in 1945. The Allies forced both Germany and Japan to surrender, after which the Allies (just the US, in the case of Japan) occupied the countries and ruled them for a number of years. WWII, then, was settled by the Allies forcing the Axis to surrender and to give the Allies complete control over their countries.