Through his marriage to Mary, who became queen of Hungary in 1382, Sigismund acceded to the Hungarian throne. However, dynastic conflicts there prevented his coronation until 1387. In the interim Mary was deposed, and Charles II (Charles III, king of Naples) became king (1385). Following Charles's death (1386) Mary was restored, and Sigismund came to power. During this period the Ottomans (Turks) were advancing in Europe, and in 1395 they invaded Hungary. Sigismund led a general European crusade against them but was crushingly defeated in 1396 by Sultan Beyazid I at Nikopol. Sigismund's absence and the death of Mary (1395) had weakened his hold on the Hungarian throne. In 1403 he put down a revolt in Hungary in support of Lancelot of Naples, the son of Charles II.