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 June 1941 , the European Axis powers launched an invasion of the Soviet Union , giving a start to the largest land theatre of war in history , which tied down the major part of the Axis ' military forces for the rest of the war .