Germany broke the Molotov–Ribbentrop Pact and invaded the Soviet Union on 22 June 1941 starting what was known in the USSR as the Great Patriotic War. The Red Army stopped the seemingly invincible German Army at the Battle of Moscow. The Battle of Stalingrad, which lasted from late 1942 to early 1943, dealt a severe blow to Germany from which they never fully recovered and became a turning point in the war. After Stalingrad, Soviet forces drove through Eastern Europe to Berlin before Germany surrendered in 1945. The German Army suffered 80% of its military deaths in the Eastern Front. Harry Hopkins, a close foreign policy advisor to Franklin D. Roosevelt, spoke on 10 August 1943 of the USSR's decisive role in the war.