Alcibiades (c. 450 BC-404 BC), an Athenian general and politician, was born at Athens. He was the son of Cleinias and Deinomache, who belonged to the family of the Alcmaeonidae. He was a near relative of Pericles, who, after the death of Cleinias at the Battle of Coronea (447 BC), became his guardian. Thus early deprived of his father's control, possessed of great personal beauty and the heir to great wealth, which was increased by his marriage, he showed himself self-willed, capricious and passionate, and indulged in the most insolent behaviour. Nor did the instructors of his early manhood supply the corrective which his boyhood lacked. From Protagoras, Prodicus, and others he learnt to laugh at the common ideas of justice, temperance, holiness and patriotism. The laborious thought, the ascetic life of his master Socrates, he was able to admire, but not to imitate or practise. On the contrary, his ostentatious vanity, his amours, his debaucheries and his impious revels became notorious. But great as were his vices, his abilities were even greater.
He took part in the Battle of Potidaea (432 BC), where his life was saved by Socrates, a service which he repaid at the Battle of Delium (424 BC). Alcibiades had great admiration of Socrates, and once said: "His nature is so beautiful, golden, divine, and wonderful within that everything he commands surely must be obeyed, even like the voice of good." As the reward for his bravery, the wealthy Hipponicus bestowed upon him the hand of his daughter. From this time he took a prominent part in Athenian politics during the Peloponnesian War. Originally friendly to Sparta, he subsequently became the leader of the war party in opposition to Nicias, and after the peace of 421 BC he succeeded by an unscrupulous trick in duping the Spartan ambassadors, and persuading the Athenians to conclude an alliance (420 BC) with Argos, Elis, and Mantineia. On the failure of Nicias in Thrace (418 BC-417 BC) he became the chief advocate of the Sicilian expedition, seeing an opportunity for the realization of his ambitious projects, which included the conquest of Sicily, to be followed by that of Peloponnesus and possibly of Carthage (though this seems to have been an afterthought). The expedition was decided upon with great enthusiasm, and Alcibiades, Nicias, and Lamachus were appointed joint commanders. But, on the day before the expedition sailed, there occurred the mysterious mutilation of the hermai, and Alcibiades was accused not only of being the originator of the crime, but also of having profaned the Eleusinian Mysteries. His request for an immediate investigation being refused, he was obliged to set sail with the charge still hanging over him.
Almost as soon as he reached Sicily he was recalled to stand his trial, but he escaped on the journey home and made his way to Sparta. Learning that he had been condemned to death in his absence and his property confiscated, he openly joined the Spartans, and persuaded them to send Gylippus to assist the Syracusans and to fortify Decelea in Attica. He then passed over to Asia Minor, prevailed upon many of the Ionic allies of Athens to revolt, and concluded an alliance with the Persian satrap Tissaphernes. But in a few months he had lost the confidence of the Spartans, and at the instigation of Agis II, whose personal hostility he had excited, an order was sent for his execution. Receiving timely information of this order he crossed over to Tissaphernes (412 BC), and persuaded him to adopt the negative policy of leaving Athens and Sparta to wear themselves out by their mutual struggles. Alcibiades was now bent on returning to Athens, and he used his supposed influence with Tissaphernes to effect his purpose. He entered into negotiations with the oligarch Peisander, but when these led to no result he attached himself to the fleet at Samos which remained loyal to the democracy, and was subsequently recalled by Thrasybulus, although he did not at once return to Athens. Being appointed commander in the neighbourhood of the Hellespont, he defeated the Spartan fleet at Abydos (411 BC) and Cyzicus (410 BC), and recovered Chalcedon and Byzantium.
On his return to Athens after these successes he was welcomed with unexpected enthusiasm (407 BC); all the proceedings against him were cancelled, and he was appointed general with full powers. His ill success, however, at Andros, and the defeat at Notium (407 BC) of his lieutenant Antiochus, led the Athenians to dismiss him from his command. He thereupon retired to the Thracian Chersonesus.
After the Battle of Aegospotami, and the final defeat of Athens, he crossed the Hellespont and took refuge with Pharnabazus in Phrygia, with the object of securing the aid of Artaxerxes against Sparta. But the Spartans induced Pharnabazus to put him out of the way; as he was about to set out for the Persian court his residence was set on fire, and on rushing out on his assassins, dagger in hand, he was killed by a shower of arrows (404 BC).
There can be no doubt that his advice to Sparta in connexion with Syracuse and the fortification of Decelea was the real cause of his country's downfall, though it is only fair to him to add that had he been allowed to continue in command of the Sicilian expedition he would undoubtedly have overruled the fatal policy of Nicias and prevented the catastrophe of 413 BC. His belated attempt to repair his fatal treachery only exposed the essential selfishness of his character. Though he must have known that his influence over the Persian satraps was slender in the extreme, he used it with the most flagrant dishonesty as a bait first to Sparta, then to the Athenian oligarchs, and finally to the democracy. Superficial and opportunist to the last, he owed the successes of his meteoric career purely to personal magnetism and an almost incredible capacity for deception.