The Ottoman Turks first entered the Balkans as mercenaries of Byzantium in the 1340s, and they returned as invaders in their own right during the following decade. Between 1359 and 1362 Sultan Murad I wrested much of Thrace from Byzantine control and captured Adrianople (modern Edirne, Turkey), commanding the route up the Maritsa valley into the heart of the Bulgarian lands. In 1364 the Turks defeated a Crusade sent by Pope Urban V to regain Adrianople, but not before the Crusaders had committed so many atrocities against Orthodox Christians that many Bulgarians came to regard Turkish rule as preferable to alliance with the Roman Catholic West.
Although Ivan Shishman, Bulgaria’s last medieval tsar, declared himself a vassal of Murad in 1371, the Ottomans continued to seek complete domination. Sofia, in the west, was seized in 1382, and Shumen, in the east, fell in 1388. A year later the defeat of the Serbs at the Battle of Kosovo sealed the fate of the entire Balkan Peninsula. In 1393, after a three-month siege, TÅrnovo was taken and burned. Ivan Shishman allegedly died in Turkish captivity three years later. With the capture of a rump Bulgarian kingdom centred at Bdin (Vidin) in 1396, the last remnant of Bulgarian independence disappeared.