December 1944, Germany made a last attempt on the Western Front by using most of its remaining reserves to launch a massive counter-offensive in the Ardennes and along the French-German border to split the Western Allies, encircle large portions of Western Allied troops and capture their primary supply port at Antwerp to prompt a political settlement. By 16 January 1945, the offensive had been repulsed with no strategic objectives fulfilled. In Italy, the Western Allies remained stalemated at the German defensive line. In mid-January 1945, the Red Army attacked in Poland, pushing from the Vistula to the Oder river in Germany, and overran East Prussia. On 4 February Soviet, British, and U.S. leaders met for the Yalta Conference. They agreed on the occupation of post-war Germany, and on when the Soviet Union would join the war against Japan. In February, the Soviets entered Silesia and Pomerania, while the Western Allies entered western Germany and closed to the Rhine river. By March, the Western Allies crossed the Rhine north and south of the Ruhr, encircling the German Army Group B. In early March, in an attempt to protect its last oil reserves in Hungary and to retake Budapest, Germany launched its last major offensive against Soviet troops near Lake Balaton. In two weeks, the offensive had been repulsed, the Soviets advanced to Vienna, and captured the city. In early April, Soviet troops captured Königsberg, while the Western Allies finally pushed forward in Italy and swept across western Germany capturing Hamburg and Nuremberg. American and Soviet forces met at the Elbe river on 25 April, leaving several unoccupied pockets in southern Germany and around Berlin. Soviet troops stormed and captured Berlin in late April. In Italy, German forces surrendered on 29 April. On 30 April, the Reichstag was captured, signalling the military defeat of Nazi Germany, and the Berlin garrison surrendered on 2 May. Major changes in leadership occurred on both sides during this period. On 12 April, President Roosevelt died and was succeeded by his vice president, Harry S. Truman. Benito Mussolini was killed by Italian partisans on 28 April. On 30 April, Hitler committed suicide in his headquarters, and he was succeeded by Grand Admiral Karl Dönitz and Joseph Goebbels. Total and unconditional surrender in Europe was signed on 7and 8May, to be effective by the end of 8 May. German Army Group Centre resisted in Prague until 11 May.