There are many factors that led to victory for the Allies on both theatres of the war. In Europe, the nation of Germany was up against the leading industrial from the battlefront(United States of America), the largest army in the world at the time with a dictator with an all or nothing blood thirsty resolve that was unmatched by any leader(USSR), and the strongest navy in the world isolated on
an island with a people with a steel hard determination in never surrendering to the Nazis(England) these 3 forces enough spelled trouble for the Germans, and their inability to tame their Japanese allies from provoking US entry into the war meant the end for the Third Reich.
