The World War II started in 1939 when Germany invaded Poland . A vast majority of population thought that it was a necessary war. From September 1939 to June 1940 Germany had many successes: Poland, Belgium, Holland, Norway and France. The German defeat was due to several reasons. One important factor was that Germany did not manage to get control of the air over the English Channel. Hitler's greatest misstep, was his decision to invade the USSR. The German army was destroyed by the long Russian winter in Leningrad, Moscow and Stalingrad. After the Russians marched through Eastern Europe to liberate the countries invaded by the Germans. In 1941 there was a American intervention, which proved disastrous for the German and Italian troops, marked turning point which paved the way to the final victory. In 1944, the Allies liberated the France. In 1945 Germany finally surrendered, after Hitler's suicide Japan remained at war, but in August was dropped the atomic bomb on Hiroshima and Nagasaki, with this act the war ended. After the war, the French, the Dutch and the British decided to abandon some of their colonies. The US also adopted the Marshall Plan to help European countries and for prevent their falling under Russian influence. The US also signed and agreement defense with western Europe, the NATO. The country which counterbalance America's powerful was he Soviet Union. Competition between these two powerful was know as the 'Cold War'. The nuclear arms race was central to the Cold War. The US and the Soviet Union built up many nuclear weapons.