 Sparta suffered several defeats during these wars, including, for the first time, the surrender of an entire Spartan unit at Sphacteria in 425 BC, but ultimately emerged victorious, primarily through the aid it received from the Persians.Under its admiral Lysander, the Persian-funded Peloponnesian fleet captured the cities of the Athenian alliance, and a decisive naval victory at Aegospotami forced Athens to capitulate.The Athenian defeat left Sparta and its military forces in a dominant position in Greece.