Two and a half millennia ago this summer, history was made. In August 480BC, a small Spartan army faced the might of Persia at Thermopylae; weeks later Athens burned; days after that, the Greek fleet smashed the Persians at Salamis; and the next year the last barbarian invaders were driven from Greece’s soil.

The Persian Wars hold legendary status: a clash of cultures, a struggle for freedom and civilization. From epitaphs written in their immediate aftermath, to the blurbs of modern histories (‘the first world empire and the battle for the West’), to the film 300, to last year’s e-festival production of Aeschylus’ Persians, the wars have been presented as an almost mythical confrontation between ‘good’ (united, civilized Greece) and ‘bad’ (an eastern tyrant).

Yet this beguiling image conceals more complex and disturbing truths. Greek unity was non-existent; the final victory on Greece’s soil was not the end of the long war; and that Cimon, who did eventually end hostilities, is largely forgotten (and the date of his victory at Eurymedon unknown), is due in no small part to democratic Athens rewriting her own past. What, then, do we really know of the Persian Wars, and how do they fit into wider Greek history?

Literary sources are unreliable. Both near-contemporary historians, Herodotus and Thucydides, had their own agendas and, since tall stories rapidly morphed into accepted orthodoxy and alternative facts became official dogma, subsequent accounts contain more dross than nuggets. Nonetheless, if we stand back to view the bigger picture, we can strip away the jingoism of romantic anecdote and reconstruct a plausible reality.

By the end of the 6th century BC, politics in the eastern Mediterranean was in a state of flux. Within 50 years, once-mighty kingdoms and empires – Media, Babylonia, Lydia and Egypt – had been subsumed by energetic Persians, whose advance seemed unstoppable. Meanwhile, traditionally agonistic Greeks, inhabitants of many hundreds of city states clustered on mainland Greece and the Aegean islands or spread out from Sicily to the Black Sea, were far from unified.

While Sparta attempted to retain recognition as the mainland’s hegemon (not least by breaking international religious laws and massacring the army of rival Argos in 494 BC), in Athens aristocrats returned from exile had seized control, strengthening their base by granting rights to the previously marginalized poor and introducing a new constitution whose name (depending on one’s point of view) can translate as either ‘People Power’ or ‘Mob Rule’: Democracy.

For reactionary Spartans this was a worrying move, a dangerous social experiment, and they tried to nip it in the bud. They failed and, when it seemed that they would try again, Athenians looked for powerful allies. They chose the Persians. But in return for military aid, the Persians made Athens’ envoys swear that it would join their empire. Many modern historians interpret the envoys’ acquiescence as an inexplicable blunder. Yet they cannot have been foolish ingenues. They must have known the consequences. Were they so hostile to the Spartans that they preferred fealty to Persia? Or were they closet oligarchs, terrified by the prospect of democracy, desperate to return to a safe status quo, where they and their rich friends, patrons of orientalizing art, could enjoy the benefits of life as Persian vassals basking in the glow of Persian peace?

Cimon at Eurymedon

Whatever the truth, the Athenian democracy tore up the treaty (to the chagrin of Persia’s Great King, Darius, for whom a man’s word was sacred). Moreover, they repelled attacks from not just their ill-willed neighbours, the Boeotians, but the militarily skilled Spartans, before sending troops to aid Greek cities on the coast of Asia Minor in an ill-conceived rebellion against Persia in 498 BC. Other than accidentally setting fire to a temple of the Mother Goddess, Cybele, in Sardis, the taskforce achieved little – but even that was enough to fan the flames of Persian ire, and with the rebellion stamped out, Darius turned his sights on treacherous, sacrilegious Athens.

It is evidence enough of Greek disunity that in 490 BC, when Persian troops disembarked at Marathon, only tiny Plataea came to Athens’ aid. Only when (against all expectation) the Persians were defeated, did the Spartan army materialize, citing as a convenient excuse for tardiness their need to celebrate a religious festival. It is just as likely that they waited for the battle’s outcome, many hoping that their pesky rival would be crushed.

Thanks to Marathon, Athens’ star shone brighter, and when (a decade later) Darius’ successor, Xerxes, was preparing a new invasion, Sparta could not afford to be slow off the mark. When Xerxes sent envoys demanding fealty, the soi-disant pious Spartans again broke international religious law and killed them, before, with the Persian army marching into Greece, they dispatched 300 soldiers (and countless helot serfs) north to Thermopylae. A suicide mission it undoubtedly would be, but it would wrest back from Athens the glory of defending Greece.

Yet still Greece could not unite. Whether through self-interest or hatred of neighbours, some such as the Boeotians, sided with the Persians, while others, such as Argos, remained dangerously neutral. Even among those few who did cooperate, there were near-fatal tensions. Although relying on Athenian ships, Sparta and her Peloponnesian allies looked on while Xerxes captured Athens and burned her temples (in retribution for the burning of the temple in Sardis); on the eve of Salamis their squabbling came close to throwing away all hope of victory; and after crushing Persia’s fleet they had to be cajoled north of the Isthmus of Corinth to face the rump of Persia’s troops at Plataea, where thanks either to a breakdown in communications or to insubordination, Spartans, Athenians and their allies fought (or did not fight) essentially discrete battles which somehow ended in Greek victory.

Even then they showed their usual propensity for seeing the smaller picture. After venting their testosterone, the collaborating (Greek) Boeotian, Athenian and Spartan armies nearly fought a pitched battle over which deserved the prize traditionally given to the bravest. In the end, they reached a compromise and gave it to inconsequential Plataea.

Nor did they show unity in the battle’s aftermath. A league intended to rid Persians from Greek lands threatened to fracture almost immediately, thanks to self-aggrandising Spartan leadership. It was the moment rival Athens had been waiting for. Magnanimously accepting the requests of disgruntled fellow members that she, not Sparta, lead them, she stage-managed an impressive yet deceptive ceremony in which each state swore allegiance not to one another, but to Athens. Within only a few decades, Athens had strengthened her grip so tightly that her notional allies found that a confederacy formed supposedly to guarantee Greek freedom had become a graspingly self-interested tyranny.

Even within Athens, factions threatened stability. Democracy was built on shifting sands, and a new breed of aristocratic politician became increasingly adept at manipulating the people’s will. Themistocles, Athens’ admiral at Salamis, architect of her powerful fleet, was vilified, ostracised, and sentenced in absentia to death – in part thanks to evidence concocted by the Spartans. Meanwhile, a charismatic leader took his place – Cimon, the son of Miltiades, victor of Marathon.

Born when his father ruled the Thracian Chersonese in the days before democracy, Cimon, who had come to Athens in his late teens, held his own views of international politics. Patrician in outlook, yet intensely public-spirited, he urged Athens to embrace cooperation with Sparta, describing the cities as two equally paired horses pulling the chariot of Greece. More important for him than rivalry with Sparta was ensuring Athenian interests and eliminating the Persian threat, since he was convinced the Persian Wars were far from over, and who knew when the next attack might come?

So, he worked tirelessly to bolster Athens’ security, economy and identity, taking the fight to Persian enclaves, ensuring safe trade routes and projecting an image of the city as a civilizing influence, utilising sculptures and paintings to link the myth of monster-slaying King Theseus with more recent events in Athens’ democratic history such as the Battle of Marathon.

Then, probably in 468 BC, tensions threatened to erupt. ‘Allied’ Naxos rebelled from Athens, and, if that were not enough, reports of Persian troops and ships assembling near the mouth of the River Eurymedon in Asia Minor set alarm bells ringing. It seemed the Persian Great King was simultaneously planning an invasion and fomenting rebellion within Athens’ empire. Cimon knew he must destroy the Persians before they could set sail. Timing his attack with precision, he led his ships to victory before, leaping from beached vessels, his soldiers routed the enemy army and sent them fleeing for the hills. As the historian Diodorus Siculus observed, ‘history knows no other such unique and crucial actions achieved on the same day on both sea and land.’ Such was the impact of the victory, and such the wealth of booty won, that Athenians named sons ‘Eurymedon’, and at least one vase painter used the opportunity to crow crudely over the humiliated Persians.

Yet, ever keen to score points and strut on the domestic stage, a new generation of Athenian politicians sought to ruin conservative Cimon. When he helped Sparta, reeling from a devastating earthquake, they undermined him at home and abroad. Soon he was ostracised, exiled for ten years – time that his opponents used to start a war with Sparta and send an expedition against the Persians in Egypt. Both ended in disaster, and by the time Cimon came home, he was needed more than ever.

There was nothing he could do about the Egyptian debacle, but he could cement peace with Sparta. With this done he channelled Athenian aggression into more campaigning against Persia, this time on Cyprus, where another invasion force appeared to be assembling. Thanks to his generalship, he dealt the Persians such a crushing blow that (although he died in theatre) the next year the two sides agreed terms for peace. Only now were the Persian Wars really over.

So, why is Cimon not a household name? The answer once more lies in Greek rivalry. Among those who ousted Cimon was Pericles. A wealthy aristocrat who courted a populist powerbase, he was determined to shape Athens in his own, not Cimon’s, image. To put Athens first and make her greater (again), he imposed trade embargoes on economic rivals and deliberately stoked international crises, not least with Sparta. Meanwhile, in speeches honouring the war dead (one of the few public occasions when Athenians were presented with an outline of their history), he honed a vision of the past where Cimon’s policies were disparaged and his achievements ignored, while those of Periclean Athens, embodied in a grandiose building programme centred on the Parthenon, were amplified beyond compare. As Thucydides (Cimon’s relative but Pericles’ admirer) predicted, such was the impact of the Periclean vision that later generations believed Athens to be greater than she really was, and Sparta lesser.

Yet Pericles’ divisive nationalism led Athens to disaster. Provoked beyond endurance, proud Sparta, determined not to lose face with her allies, rallied them under the slogan of ‘freedom for all Greeks’ and embarked on a lengthy war, whose effect was not just to exhaust Greek resources and morale, but to bring the Persians back into the fray, sacrifice Greek cities to the age-old enemy, and in the end allow a Persian king to dictate peace terms to Greeks.

Early in that war, self-interested Athens betrayed Plataea, her one ally at Marathon to whom she had promised her support, standing cynically by while Plataean citizens were tried by a Spartan kangaroo court and executed in cold blood. In comparison, the betrayal of Cimon’s memory by Athens’ self-promoting politicians might seem inconsequential. Yet the two are linked. Both reveal attempts to airbrush history to suit the present moment, and both ignore inconvenient truths. Of course, in drawing on the myth of Theseus, Cimon manipulated the past too. But today’s historian must not. Rather, we must try to look behind the legends to the raw unvarnished truth – even if it shatters our illusions.

David Stuttard is an author, translator, classicist and theatre director. He is currently a Fellow of Goodenough College, London. His latest book, Phoenix: A Father, a Son, and the Rise of Athens, on the Persian Wars and the Athenian Empire, is out now.

Aspects of History Issue 8 is out now.