By 1937, he was comfortable enough to put his master plan, as outlined in Mein Kampf, into effect. Calling his top military aides together at the conference in November 1937, he outlined his plans for world domination. Those who objected to the plan were dismissed. Hitler's army invaded Poland on September 1, 1939, sparking France and England to declare war on Germany. A Blitzkrieg of German tanks and infantry swept through most of Western Europe as nation after nation fell to the German war machine. In 1941, Hitler ignored a non-aggression pact he had signed with the Soviet Union in August 1939. Several early victories after the invasion of the Soviet Union in June 1941, were reversed with crushing defeats at Moscow and Stalingrad. The United States entered the war in December 1941. By 1944, the Allies invaded occupied Europe at Normandy Beach on the French coast, German cities were being destroyed by bombing, and Italy, Germany's major ally under the leadership of Fascist dictator Benito Mussolini, had fallen. Several attempts were made on Hitler's life during the war, but none was successful. As the war appeared to be inevitably lost, Adolf Hitler killed himself on April 30, 1945.