The Delian League and the Age of Pericles
Leading the Delian League against a renewed Persian threat, Athens reached its height; under Pericles its direct democracy, in which all citizens decided affairs in the assembly, took its full form.
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Around 478 BC Athens formed the Delian League with the Aegean poleis, based on the island of Delos, to guard against a new Persian attack. Members contributed ships or money, but in 454 BC Athens moved the league treasury to Athens and forced back states that tried to leave, turning the league into an Athenian empire in all but name.
Under Pericles, who led Athens from about 461 BC, the democracy reached its full form. All adult male citizens decided laws, war and peace in the assembly; most officials and jurors were chosen by lot, and pay for public service let poor citizens take part (direct democracy). Women, foreigners and slaves, however, had no political rights.
League money rebuilt the Acropolis with the Parthenon, and tragedy, comedy and sculpture flourished. But Athenian expansion alarmed Sparta and led to the Peloponnesian War.