may have been triggered by Miltiades's prosecution, and used by the Athenians to try to stop such power-games among the noble families. Certainly, in the years (487 BC) following, the heads of the prominent families, including the Alcmaeonids, were exiled. The career of a politician in Athens thus became fraught with more difficulty, since displeasing the population was likely to result in exile. Themistocles, with his power-base firmly established among the poor, moved naturally to fill the vacuum left by Miltiades's death, and in that decade became the most influential politician in Athens. However, the support of the nobility began to coalesce around the man who would become Themistocles's great rival—Aristides. Aristides cast himself as Themistocles's opposite—virtuous, honest and incorruptible—and his followers called him "the just". Plutarch suggests that the rivalry between the two had begun when they competed over the love of a boy: "... they were rivals for the affection of the beautiful Stesilaus of Ceos, and were passionate beyond all moderation." During the decade, Themistocles continued to advocate the expansion of Athenian naval power. The Athenians were certainly aware throughout this period that the Persian interest in Greece had not ended; Darius's son and successor, Xerxes I, had continued the preparations for the invasion of Greece. Themistocles seems to have realised that for the Greeks to survive the coming onslaught required a Greek navy that could hope to face up to the Persian navy, and he therefore attempted to persuade the Athenians to build such a fleet. Aristides, as champion of the zeugites (the upper, 'hoplite-class') vigorously opposed such a policy. In 483 BC, a massive new seam of silver was found in the Athenian mines at Laurium. Themistocles proposed that the silver should be used to build a new fleet of 200 triremes, while Aristides suggested it should instead be distributed among the Athenian citizens. Themistocles avoided mentioning Persia, deeming that it was too distant a threat for the Athenians to act on, and instead focused their attention on Aegina. At the time, Athens was embroiled in a long-running war with the Aeginetans, and building a fleet would allow the Athenians to finally defeat them at sea. As a result, Themistocles's motion was carried easily, although only 100 warships of the trireme type were to be built. Aristides refused to countenance this; conversely Themistocles was not pleased that only 100 ships would be built. Tension between