The peace with Germany was tense, as both sides were preparing for the military conflict, and abruptly ended when the Axis forces led by Germany swept across the Soviet border on 22 June 1941. By the autumn the German army had seized Ukraine, laid a siege of Leningrad, and threatened to capture the capital, Moscow, itself. Despite the fact that in December 1941 the Red Army threw off the German forces from Moscow in a successful counterattack, the Germans retained the strategic initiative for approximately another year and held a deep offensive in the south-eastern direction, reaching the Volga and the Caucasus. However, two major German defeats in Stalingrad and Kursk proved decisive and reversed the course of the entire World War as the Germans never regained the strength to sustain their offensive operations and the Soviet Union recaptured the initiative for the rest of the conflict. By the end of 1943, the Red Army had broken through the German siege of Leningrad and liberated much of Ukraine, much of Western Russia and moved into Belarus. During the 1944 campaign, the Red Army defeated German forces in a series of offensive campaigns known as Stalin's ten blows. By the end of 1944, the front had moved beyond the 1939 Soviet frontiers into eastern Europe. Soviet forces drove into eastern Germany, capturing Berlin in May 1945. The war with Germany thus ended triumphantly for the Soviet Union.