Alcibiades was born in Athens, in the deme of Skambonidai, to Kleinias and Deinomache of the Alkmaionidai family. He was a near relative of Pericles who after the death of Kleinias became his guardian.

He was a great admirer of Sokrates, although he was unable to follow his mentor’s teachings, as his ostentatious vanity, his amours and his impious revels indicate.

Alcibiades was involved with politics after the Peace of Nikias in 421 BCE. During the Peloponnesian War, he was responsible for persuading Athens to join an alliance against Sparta. When Sparta attacked Argos, Alcibiades led an Athenian force to help the Argives, but Athens and the allies were beaten at Mantinea (418 BCE).

Alcibiades was the chief promoter of the Sicilian campaign and was one of the three commanders, along with Nikias and Lamachos, of the Athenian forces (415 BCE). When they arrived at Sicily, he proposed an attempt to win allies rather than attacking the hostile cities of Selinus and Syracuse at once. In the meantime, Alcibiades had been summoned home to stand trial for the mutilation of the statues of Hermes, a crime of which he was almost certainly innocent. Instead of that, he fled to Sparta, where he persuaded King Agis I to send general Gylippos to assist the Syracusans, and at the same time to fortify Dekeleia outside Athens. His advice to the Spartans sealed the fate of the Athenian forces at Sicily, resulting to one of the worst defeats in Athens’ history.

Alcibiades later fell into trouble with the Spartans, and in 413 BCE he fled to the protection of the Persian satrap Tissaphernes. After the oligarchy of the Four Hundred fell in Athens (411 BCE), he was recalled at the request of Thrasyboulos. The people of Athens welcomed Alcibiades home, fully restored his rights, returned his property, and revoked the curse that had been placed upon him. Athens had a short era of greatness as Alcibiades commanded brilliantly the Athenian fleet in the Aegean and in 410 BCE won a victory over the Peloponnesian fleet off Cyzicus, and later recovered Chalkedon and Byzantium. However, Lysander, the new Spartan commander, defeated the Athenian fleet at Notium in c.406 BCE, so Alcibiades was exiled. He went to a house he owned on the Thracian Chersonesos. There, in 405 BCE, he attempted to warn the Athenian fleet at Aigospotami against a surprise attack by the Spartans, but his advice was ignored. In 404 BCE at the request of Lysander, the Persian satrap Pharnabazus had Alcibiades murdered.

References
Plutarch, Alcibiades (translated by John Dryden)
Available at: http://www.acs.ucalgary.ca/~vandersp/Courses/texts/plutarch/plutalci.html

Alcibiades entry at Wikipedia
Available at: http://en.wikipedia.org/wiki/Alcibiades