After the defeat of the Persians in 480/479 Athens was  united as never before.  There was little division in the social classes, and leaders of the Alcmeonid party like Aristides cooperated with rivals like Themistocles and even with Cimon, of the enemy Philaid clan, in the continuing war against Persia.  The lowest class, the day-laboring thetes , was doing better than ever as rowers in the fleet.  Ostracism (votes to expell prominent leaders) continued to play a part in ensuring harmony.  Normally, all magistrates had to undergo a scrutiny at the end of their year of office, but the process of ostracism was more rigorous.  Every year the Assembly voted on whether or not to hold an ostrakophoria, and if it decided to go ahead, 6000 votes against a citizen was enough to exile him for ten years, though he did not lose his property, as he would have in the case of a real exile.  On the other hand, an ostracized Athenian was forbidden to leave the region, lest he intrigue with enemies.

During the war years, the Areopagus and the board of 10 strategoi had become the most important political forces in the state. The Areopagus had gained great credit for the wise and orderly way in which it arranged the evacuation of Athens during the Persian invasion.  Themistocles, a strong democrat, was the dominant politician until he was implicated in the plots of the Spartan general Pausanias and ostracized. He threw himself on the Great King’s mercy and reminded him that he had warned the king at Salamis that the Greeks were ready to desert–true.  Historical judgments have been harsh on Themistocles, but no man, honest or corrupt, ever served his country better.

Themistocles was succeeded by a more stable character and greater military leader, Cimon, son of Miltiades, who represented the more conservative part of the population. Cimon had come to prominence in 480, during the debate over how to face the Persians.  Those who wished to stay and fight must have pointed to the example of Miltiades’ victory at Marathon.  Miltiades’ handsome son thought differently, and he led a procession of his noble young friends up to the Acropolis and there he dedicated the bridle her carried–the symbol of the old aristocratic cavalry–to the goddess, he took up a hoplite spear and went to join the fleet.

Cimon, though viewed as something of a simpleton and a womanizer in his early youth, was also an astute politician: He paid his father’s fine, arranged for his sister to marry the wealthy Callias, and himself married an Alcmeonid, whom Plutarach says he adored.  He was the most generous man alive and allowed the poor to go into his fields for food and served a simple dinner to any of his fellow demesmen who needed it.  And yet, rather than cultivating a popular party, he was leader of the conservatives. [Plutarch, Cimon ]

His policies were clear: war with Persia, peace with Sparta, and a maintenance of the successful status quo established by Cleisthenes: a balanced constitution in which both the people and the aristocrats were able to carry out their proper functions, freed from the dictatorship of the mob and the oppression of an oligarchy.  Under Cimon’s leadership, Athens became mistress of the Aegean, and was at peace both with her allies and with the Spartan alliance.  His very success antagonized the democrats led by Ephialtes and Pericles, and Pericles prosecuted him for bribery, during the scrutiny after his return from his victorious campaign on the Eurymedon.  Cimon was acquitted and might have stayed in power had he not made the mistake of going to the aid of the Spartan allies during the Messenian Revolt.  The revolt had started about 469 and the Spartans, partly because of the great earthquake, were having a rough time.  The rebels had established a fortified base of operations at Ithome and it was not until the end of the decade that the Spartans were able to suppress the rebellion.

The democrats in Athens by now regarded Sparta as a rival and enemy and did not wish to send help.  There were suspicions on both sides.  Athens had been attempting to subdue Thasos, which Miltiades had failed to take after Marathon, and the Thasians appealed to Sparta for help.  The Spartans considered the proposal,
but they were embroiled in their trouble closer to home.  Despite the democrats’ opposition, however, Cimon (in 462), who admired the Spartans and wanted peace with them, secured authorization to lead Athenian reinforcements in person and all might have gone well if the Spartans had not begun to suspect that Athenian democrats, some of whom sided with the Messenian rebels, might cause a revolution in Laconia.  The ever-suspicious Spartans asked the Athenians to leave, which was an affront to be resented.
Upon returning to Athens, Cimon lost face and influence.  The radicals could now complain that he was a conservative, a Spartan-sympathizer, and–worst of all–a failure.  He was finished in politics, and the radical democrats, led by Ephialtes, waged a campaign to strip Athens of all constitutional impediments to mob rule.  Ephialtes and his junior colleague Pericles resorted to a trick common on the left: first discredit the institutions you want to destroy.  They prosecuted member after member of the Council, and during Cimon’s absence, the Council of the Areopagus had already been stripped of most of its powers (except the power to try homicide).  Most of the other powers were transferred to the Heliaea, which was basically a court constituted by the Assembly, thus any citizen was eligible and paid for jury duty  Justice itself was no longer the primary object of the courts, but the will of the people.

The democrats’ greatest political triumph was the ostracism of Cimon himself in 461.  He spent most of the rest of his life in exile, though he was allowed to return (perhaps before the ten year period had fully elapsed and in the late 450’s, he was entrusted to negotiate a peace with Sparta, with whom Athens was by now at war, and he went at the head of Athenian troops to Cyprus, where he died fighting.
Within two years of Cimon’s expulsion, Athens was not only continuing her democratic revolution, but she was at war on several fronts: not only across the sea in Egypt, Cyprus, and Phoenicia, but closer to home in the Saronic Gulf, at Aegina and Megara.  By 456, the probable year of the poet Aeschylus’ death, she was at war, though not openly, with her former ally, Sparta.

This then is the political context in which Aeschylus composed his masterpiece.