The Sicilian Expedition was an Athenian military expedition to Sicily, which took place during the period from 415 BC to 413 BC (during the Peloponnesian War). The expedition was hampered from the outset by uncertainty in its purpose and command structure—political maneuvering in Athens swelled a lightweight force of twenty ships into a massive armada, and the expedition's primary proponent, Alcibiades, was recalled from command to stand trial before the fleet even reached Sicily—but still achieved early successes. Syracuse, the most powerful state on Sicily, responded exceptionally slowly to the Athenian threat and, as a result, was almost completely invested before the arrival of a Spartan general, Gylippus, galvanized its inhabitants into action. From that point forward, however, as the