The Ottomans captured Constantinople with ease in 1453 and advanced southwards into the Balkan peninsula capturing Athens in 1458. The Greeks held out in the Peloponnese until 1460, and the Venetians and Genoese clung to some of the islands, but by 1500 most of the plains and islands of Greece were in Ottoman hands. The mountains of Greece were largely untouched, and were a refuge for Greeks to flee foreign rule and engage in guerrilla warfare.