Empire. The capture of Gallipoli by the Ottomans in 1354 kicked off a rapid Turkish expansion in the southern Balkans, conducted both by the Ottomans themselves and by semi-independent Turkish ghazi warrior-bands. By 1369, the Ottomans were able to conquer Adrianople (modern Edirne), which became their new capital until 1453. Thessalonica, ruled by Manuel II Palaiologos (r. 1391–1425) itself surrendered after a lengthy siege in 1383–1387, along with most of eastern and central Macedonia, to the forces of Sultan Murad I. Initially, the surrendered cities were allowed complete autonomy in exchange for payment of the kharaj poll-tax. Following the death of Emperor John V Palaiologos in 1391, however, Manuel II escaped Ottoman custody and went to Constantinople, where he was crowned emperor, succeeding his father. This angered Sultan Bayezid I, who laid waste to the remaining Byzantine territories, and then turned on Chrysopolis, which was captured by storm and largely destroyed. Thessalonica too submitted again to Ottoman rule at this time, possibly after brief resistance, but was treated more leniently: although the city was brought under full Ottoman control, the Christian population and the Church retained most of their possessions, and the city retained its institutions. Thessalonica remained in Ottoman hands until 1403, when Emperor Manuel II sided with Bayezid's eldest son Süleyman in the Ottoman succession struggle that broke out following the crushing defeat and capture of Bayezid at the Battle of Ankara against Tamerlane in 1402. In exchange for his support, in the Treaty of Gallipoli the Byzantine emperor secured the return of Thessalonica, part of its hinterland, the Chalcidice peninsula, and the coastal region between the rivers Strymon and Pineios. Thessalonica and the surrounding region were given as an autonomous appanage to John VII Palaiologos. After his death in 1408, he was succeeded by Manuel's third son, the Despot Andronikos Palaiologos, who was supervised by Demetrios Leontares until 1415. Thessalonica enjoyed a period of relative peace and prosperity after 1403, as the Turks were preoccupied with their own civil war, but was attacked by the rival Ottoman pretenders in 1412 (by Musa Çelebi) and 1416 (during the uprising of Mustafa Çelebi against Mehmed I). Once the Ottoman civil war ended, the Turkish pressure on the city began to increase again. Just as during the 1383–1387 siege, this led to a sharp division of opinion within the city between factions supporting resistance, if necessary with Western help, or