After an initial devastating advance, the Wehrmacht suffered its first defeat in war at Moscow. The Germans and their allies tried in 1942 to advance southward, to the Caucasus. After six months of fighting, at Stalingrad they suffered a pivotal defeat. In late 1943, in the wake of Battle of Kursk, the Soviet Red Army gained the initiative with a series of major victories, culminating in the ultimate advance of Soviet forces into Eastern Europe during 1944 and over Germany in 1945, concluded by the Battle of Berlin. The war against the USSR inflicted loss of lives (both civilian and military), on a scale greater than any countries in the war. Following the end of the war in Europe and the American atomic bombing of Hiroshima, the USSR joined the war against Japan. The Soviet Union, as one of the main victors, gained one of the permanent seats in the United Nations Security Council. After the war, the Soviet sphere of influence was widened to cover most of Eastern Europe, formalized in the Warsaw Pact. The Soviet Union came to be considered one of the two superpowers of the Cold War.