The emperor Justinian I fortified Gallipoli and established important military warehouses for corn and wine there, of which some Byzantine ruins can still be seen. After the capture of Constantinople by the Latins in 1204, Gallipoli passed into the power of the Republic of Venice. In 1294 the Genoese defeated a Venetian force in the neighbourhood. The Catalan Company, a body of Almogavars, under Roger de Flor, established themselves here in 1306, and after the death of their leader massacred almost all the citizens; they were vainly besieged by the allied troops of Venice and the Byzantine Empire, and withdrew in 1307, after dismantling the fortifications. After the city's defenses were damaged in an earthquake, it was conquered by Turks in 1354 and became the first stronghold of the Ottoman Empire in Europe. Sultan Bayezid I (1389–1403) built a castle and tower there which can still be seen. In 1416 the Venetians under Pietro Loredan defeated the Turks here. Gallipoli is the site of "tombs of the Thracian kings", which refers to the graves of the Islamic writers Ahmed Bican (died 1466) and his brother Mehmed Bican (died 1451).