In 416, the Sicilian city of Egesta requested Athens’s help. Athens had been looking for an excuse to establish a presence in Sicily. Egesta promised—falsely, as the Athenians would learn too late—that it had the resources to support an Athenian expedition. The city’s assembly convened to debate whether to launch an expedition to Sicily and expand their empire, which most supported. Nicias argued against the expedition, urging Athens to secure her current empire before pursuing a larger one and noting that the Sicilians had historically preferred to ally with Sparta. If Athens failed, their enemies would be emboldened to act against them. Alcibiades countered in favor of launching the expedition, insisting the Athenians had nothing to lose as they were militarily strong and had built their empire by responding enthusiastically to requests for support. In a second speech, Nicias intended to discourage the Athenians by pointing out the tremendous resources, financial and human, that the expedition would require. However, instead of discouraging them, it made them even more eager.

Before the expedition launched, religious statues (hermae) around the city were vandalized, which citizens viewed as a bad omen. Alcibiades was accused but permitted to join the expedition, which launched with much pomp and enthusiasm.