 The ancient city of Corfu, known as Korkyra, took part in the Battle of Sybota which was a catalyst for the Peloponnesian War, and, according to Thucydides, the largest naval battle between Greek city states until that time.Thucydides also reports that Korkyra was one of the three great naval powers of fifth century BC Greece, along with Athens and Corinth.Medieval castles punctuating strategic locations across the city are a legacy of struggles in the Middle Ages against invasions by pirates and the Ottomans.