The Nazi dream began to crumble in 1941-1945 as the tide of the war turned against Germany. The invasion of the Soviet Union in Operation Barbarossa proved to be a costly mistake, as the German army became bogged down in a protracted and bloody conflict. The declaration of war by the United States in December 1941 further stretched German resources and opened a second front in the Atlantic. As the Allies gained momentum, the German military suffered a series of crushing defeats, including the Battle of Stalingrad in 1943 and the D-Day landings in Normandy in 1944. By 1945, Germany was on the verge of collapse, and the Nazi regime was finally overthrown with the surrender of the German army in May.
