Though the Allies' economic and population advantages were largely mitigated during the initial rapid blitzkrieg attacks of Germany and Japan, they became the decisive factor by 1942, after the United States and Soviet Union joined the Allies, as the war largely settled into one of attrition.
Meski keunggulan ekonomi dan populasi Sekutu dimanfaatkan besar-besaran selama serangan blitzkrieg awal Jerman dan Jepang, mereka menjadi faktor penentu pada tahun 1942, setelah Amerika Serikat dan Uni Soviet bergabung dengan Sekutu, setelah sebagian besar perang ini menjadi perang atrisi.