In 1938 , at the outbreak of World War II , which had a larger population , the Western Allies ( United Kingdom , France , Poland and British Dominions ) or the European Axis ( Germany and Italy )
In 1943 , with a series of German defeats on the Eastern Front , the Allied invasion of Italy which brought about that nation 's surrender , and American victories in the Pacific , the Axis lost the initiative and undertook strategic retreat on all fronts .