The tyranny at Megara was a brief one, but we know that Theagenes built an aqueduct for his city and made it a serious commercial rival to Athens. At Athens Peisistratus stood forth as champion of the poor shepherds of the Hill against the wealthier parties of the Coast and the Plain. He succeeded where Cylon had failed in gaining command of the Acropolis with his bodyguard. Twice the Athenians managed to expel him, but each time he got back, the first time by dressing up a tall and handsome woman as the goddess Athena and driving into the city with her, and the second time by hiring a contingent of horsemen from Eretria, with money which he had obtained by prudent operations in the goldfields of Thrace. From first to last he and his sons were in power from 560 to 510. It is difficult to estimate his services to Athens, for later generations did their utmost to deny and conceal them, giving some of his achievements to Solon and some to Theseus, and some even to Erechtheus. He founded an early Athenian empire. He won the island of Salamis from Megara, and until she possessed Salamis Athens had no open road to the sea. Later Athenians ascribed this feat to Solon. He regained Sigeum, on the Troad, after a war with Mitylene. He established the elder Miltiades as tyrant of the Thracian Chersonese. In these movements his policy was obviously to open up trade with the Black Sea, the granary of Greece. He extended olive-culture in Attica. He probably began to work the silver-mines at Laurium, which were thenceforth the principal source of Athenian revenue. He made the unfree tillers of the soil into peasant proprietors by confiscating the estates of his noble opponents. He was allied with Sparta and Argos, Thebes and Thessaly and Naxos. He introduced a police armed with bows into the city of Athens.