After taking Belgrade, the road to Hungary and Austria lay open, but Suleiman turned his attention instead to the Eastern Mediterranean island of Rhodes, the home base of the Knights Hospitaller. Suleiman built a large fortification, Marmaris Castle, that served as a base for the Ottoman Navy. Following the five-month Siege of Rhodes (1522), Rhodes capitulated and Suleiman allowed the Knights of Rhodes to depart. The conquest of the island cost the Ottomans 50,000 to 60,000 dead from battle and sickness (Christian claims went as high as 64,000 Ottoman battle deaths and 50,000 disease deaths).