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Factional Politics: The Ostracism of Themistokles A group of ostraka found together in a pit on the North Slope of the Acropolis is of special interest. There were 190 ostraka, mostly the round feet of ... These ships proved crucial in the decisive victory of the Greek fleet over the Persians at Salamis in 480 B.C., as did Themistokles' own guile in tricking the Persians into fighting in the narrow straits.