 Complete the following phrase:  The author writes that by Poland not opposing Adolf Hitler in September 1939, the Second World War starts on April 9, 1940 by a German attack on Western Europe. After capturing Paris and defeating Belgium, the Netherlands, Norway, Denmark and France, on June 21, 1941, the Wehrmacht, together with the Polish Army, invades the Soviet Union. By the winter of 1941-1942, the Soviet Union ceases to exist. Poland and Germany divide its territory, but soon, mutual relationships deteriorate. Meanwhile, Germany keeps fighting the United Kingdom and the United States. The war is costly, and by 1944, all of the main units of the Wehrmacht are in Western Europe fighting the Allies, who 