He sent one army to Novo Brdo, and with the other, the main one, which numbered about 130,000 men (probably 30,000 men), in late April or early May 1439 began the siege of Smederevo. After three months of siege, in early August 1439 Smederevo was fall. In Fact, defenders led by despot's son Grgur Brankovic and Thomas Kantakouzenos are remaining without food after which they dicide to open the town's gates to Muslims and on thet way prevent robbery and massacre. Meanwhile, the despot George went to exile on the camp of the Hungarian king Albert II. On the news of the fall of Serbia under Islam a fear was spread in Hungary. In the swampy part of the Danube frontier near Belgrade, King Albert fell ill of dysentery in September 1439. He died next month on the way to Vienna. Albert's death initiated a Hungarian Civil War, which lasted for twenty years (1439-1458) and ended only with the arrival of Matthias Corvinus on the Hungarian throne. In December 1439, as Hungarian magnate despot George was nominated his son Lazar for marriage to Elizabeth, who wanted to preserve the throne but was rejected because he was "schismatic". The more serious candidate was King of Poland Władysław III of the Lithuanian Dynasty of the Jegiellonian. At the beginning of 1440, Elizabeth gave her consent to the marriage with the young Władysław. Marriage with him would bring an alliance with Poland and an end to the conflict against Hungary (because it was known that Murad's deputies were in Poland who offered an alliance against Hungary). Meanwhile, in February 1440, Elizabeth gave birth to a son Ladislaus the Posthumous and then changed her mind about marrying with Władysław. On May 1440, the newborn baby is crowned with a stolen crown for the king. Then Elizabeth and her son took refuge to the German King Frederick III in Vienna. In the party that supported Ladislaus for the king, as the grandson of King Sigismund, they were George Brankovic, Nicholas of Ilok, Ladislaus Garai, Frederick II and Ulrich II of Celje. On the eve of the arrival of Władysław, despot George decided to leave Hungary. Despot George was offended that he, and especially his son Lazar, had missed the royal crown.