In 1453, Ottomans conquered Constantinople, the capital city of the Byzantine Empire. In 1460, they conquered the Despotate of the Morea, in 1461 the Empire of Trebizond, in 1475 the Principality of Theodoro and by 1500 most of the plains and islands were in Ottoman hands. Holdouts included Rhodes, conquered in 1522, Cyprus in 1571, Crete, retained by the Venetians until 1669, and the Ionian islands which remained primarily under the rule of the Republic of Venice.