In particular, the corsair Dragut was proving to be a major threat to the Christian nations of the central Mediterranean. Dragut and the Knights were continually at loggerheads. In 1551, Dragut and the Ottoman admiral Sinan decided to take Malta and invaded the island with a force of about 10,000 men. After only a few days, however, Dragut broke off the siege and moved to the neighbouring island of Gozo, where he bombarded the Cittadella for several days. The Knights' governor on Gozo, Gelatian de Sessa, having decided that resistance was futile, threw open the doors to the Cittadella. The corsairs sacked the town and took virtually the entire population of Gozo (approximately 5,000 people) into captivity. Dragut and Sinan then sailed south to Tripoli, where they soon seized the Knights' garrison there. They initially installed a local leader, Aga Morat, as governor, but subsequently Dragut himself took control of the area.