In the century after the death of Osman I, Ottoman rule began to extend over Anatolia and the Balkans. The earliest conflicts began during the Byzantine–Ottoman wars, waged in Anatolia in the late 13th century before entering Europe in the mid-14th century, followed by the Bulgarian–Ottoman wars and the Serbian–Ottoman wars waged beginning in the mid 14th century. Much of this period was characterised by Ottoman expansion into the Balkans. Osman's son, Orhan, captured the northwestern Anatolian city of Bursa in 1326, making it the new capital of the Ottoman state and supplanting Byzantine control in the region. The important port city of Thessaloniki was captured from the Venetians in 1387 and sacked. The Ottoman victory in Kosovo in 1389 effectively marked the end of Serbian power in the region, paving the way for Ottoman expansion into Europe. The Battle of Nicopolis for the Bulgarian Tsardom of Vidin in 1396, widely regarded as the last large-scale crusade of the Middle Ages, failed to stop the advance of the victorious Ottoman Turks.