Greek politics were highly personalized. The very existence of the institution of ostracism, for example, whereby individuals were sent into exile by means of a popular vote, attests to the fact. Pericles owed his dominance of Athenian political life in large part to the fact that he had successfully rallied opposition to Thucydides (son of Milesias, to distinguish him from the historian) in the 440s bce. Thucydides had been the first to create anything like a political party in Athens, encouraging his partisans to sit together in the assembly. Thucydides' power came to an abrupt end when he was ostracized in 443 bce, and Pericles was pre-eminent for the next decade or more. On Pericles' death in 429 there was a struggle for the succession, at the level of succeeding to the grip on Athenian politics that Pericles had enjoyed, rather than any formal position beyond an annual election to a generalship. There were ten generals each year, and any pre-eminence was due to the Athenian public's view as to who appeared to carry the most influence. Cleon (who was not at first a general) succeeded for a time in laying claim to Pericles' mantle, and after his death Nicias came to the fore. Both were challenged, either overtly or in the most underhand fashion, by Pericles' ward Alcibiades (c.452–404 bce), an individual who regarded himself from a very early age as his guardian's true successor.

Alcibiades' conduct attracted innumerable anecdotes, many of which have come down to us. These go far beyond the story of his generalships, his joint command on the ill-fated Sicilian campaign (an expedition he had done much to foster), his desertion to Athens’ Spartan enemies, and his triumphant return to Athens towards the end of his life. They tell of his irrationality, his selfishness, his greed, his flamboyance and above all his ambition. It was this aspect of his personality that polarized Athenian opinion. Some were for tolerating the extraordinary individual whose persuasiveness camouflaged many of his failings, while others were scandalized by his excesses and saw in the person of Alcibiades the emergence of a new tyrant, of a kind that their ancestors had successfully sent into exile decades earlier.