Page "Peloponnesian War" Paragraph 23

The Athenians did not act solely from altruism: rallied on by Alcibiades, the leader of the expedition, they held visions of conquering all of Sicily.

Syracuse, the principal city of Sicily, was not much smaller than Athens, and conquering all of Sicily would have brought Athens an immense amount of resources.

In the final stages of the preparations for departure, the hermai ( religious statues ) of Athens were mutilated by unknown persons, and Alcibiades was charged with religious crimes.

Alcibiades demanded that he be put on trial at once, so that he might defend himself before the expedition.

The Athenians however allowed Alcibiades to go on the expedition without being tried ( many believed in order to better plot against him ).

After arriving in Sicily, Alcibiades was recalled back to Athens for trial.

Fearing that he would be unjustly condemned, Alcibiades defected to Sparta and Nicias was placed in charge of the mission.

After his defection, Alcibiades claimed to the Spartans that the Athenians planned to use Sicily as a springboard for the conquest of all of Italy and Carthage, and to use the resources and soldiers from these new conquests to conquer the Peloponnese.