After a successful invasion by the in the early 16th century, Charles V entrusted its defense to the Knights of St. John in Malta. Lured by the piracy that spread through the Maghreb coastline, adventurers such as Barbarossa and his successors consolidated Ottoman control in the central Maghreb. The Ottoman Turks conquered Tripoli in 1551 under the command of Sinan Pasha. In the next year his successor Turgut Reis was named the Bey of Tripoli and later Pasha of Tripoli in 1556. As Pasha, he adorned and built up Tripoli, making it one of the most impressive cities along the North African coast. By 1565, administrative authority as regent in Tripoli was vested in a "pasha" appointed directly by the "sultan" in Constantinople. In the 1580s, the rulers of Fezzan gave their allegiance to the sultan, and although Ottoman authority was absent in Cyrenaica, a "bey" was stationed in Benghazi late in the next century to act as agent of the government in Tripoli.