When the Greek cities of Ionia rose up against Persian rule, Darius vowed to make an example not just of them, but of the Greek poleis that had aided them, including Athens. This led to the Persian War, one of the most famous conflicts in ancient history. It is remembered in part because it pitted an underdog, Greece, against a massive empire, Persia. It is remembered because the underdog won, at least initially. It is also remembered, unfortunately, for how the conflict was appropriated by proto-racist beliefs in the superiority of “The West.” Because the Greeks saw the conflict in terms of the triumph of true, Greek, civilization over barbaric tyranny, and the surviving historical sources are told exclusively from the Greek perspective, this bias has managed to last down until the present – consider the recent movie adaptations of the most famous battles of the Persian War, 300 and 300: Rise of an Empire, in which the Persians are depicted as being literally monstrous, ruled over by a comically evil, eight-foot-tall king. The fact that both Sparta and Athens were slave-based societies is not part of those movies' narratives.
The war began in 490 BCE, when the Persians, with about 25,000 men, landed at Marathon, a town 26 miles from Athens. The Athenians sent a renowned runner, Pheidippides, to Sparta (about 140 miles from Athens) to ask for help. The Spartans agreed, but said that they could only send reinforcements when their religious ceremonies were complete in a few days. Pheidippides ran back to Athens with the bad news, but by then the Athenians were already engaged with the Persians.
There were about 25,000 Persian troops – this was an “expeditionary force,” not a large army, against which the Athenians fielded 10,000 hoplites. The Athenians marched out to confront the Persians. The two armies camped out and watched each other for a few days, then the Persians dispatched about 10,000 of their troops in naval transports to attack Athens directly; this prompted a gamble on the part of the leading Athenian general (named Miltiades) to attack the remaining Persians, rather than running back to Athens to defend it. The ensuing battle was a decisive show of force for the Greeks: the citizen-soldier hoplites proved far more effective than the conscript infantry of the Persian forces. The core of the Persian army, its Median and Persian cavalry, fought effectively against the Athenians, but once the Athenian wings closed in and forced back the infantry, the Persians were routed.
The Greeks were especially good at inflicting casualties without taking very many – the Persians supposedly lost 33 men to every Athenian lost in the battle (6,400 Persian dead to 192 Athenians). There is also a questionable statistic from Greek sources that it was more than that – as many as 60 Persians per Athenian. Whatever the real number, is was a crushing victory for the Athenians. A later (almost certainly fabricated) account of the aftermath of the battle claimed that Pheidippides was then sent back to Athens, still running, to report the victory. He dropped dead of exhaustion, but in the process he ran the first “marathon.”
It is entirely possible that, despite this victory, the Greeks would have still been overwhelmed by the Persians if not for setbacks in Persia and its empire. A major revolt broke out in Egypt against Persian rule, drawing attention away from Greece until the revolt was put down. Likewise, it took years to fully “activate” the Persian military machine; preparation for a full-scale invasion took a full decade to reach completion. Darius died in 486 BCE, in the middle of the preparations, which disrupted them further while his son Xerxes consolidated his power.
In the meantime, the Greeks were well aware that the Persians would eventually return. A new Athenian general, Themistocles, convinced his countrymen to spend the proceeds of a silver mine they had discovered on a navy. Athens went into a naval-building frenzy, ending up with hundreds of warships called triremes, rowed by those free Athenians too poor to afford armor and weapons and serve as hoplites, but who now had an opportunity to directly aid in battle as sailors. This was perhaps the first time in world history that a fairly minor power transformed itself into a major power simply by having the foresight to build an effective navy.
The Persians had finally regrouped by 480 BCE, ten years after their first attempt to invade. Xerxes I, the new king, dispatched a huge army (as many as 200,000 soldiers and 1,200 ships) against Greece, supported by a navy over twice as large as that of the Athenians. The Greek poleis were, for the most part, terrified into submission, with only about 6% of the Greek cities joining into the defensive coalition created by Athens and Sparta (that being said, within that 6% were some of the most powerful poleis in Greece). The Spartans took leadership of the land army that would block the Persians in the north while the Athenians attacked the Persian navy in the south.
The Spartan-led force was very small compared to the Persian army, but for several days they held the Persians back at the Battle of Thermopylae, a narrow pass in which the Persians were unable to deploy the full might of their (much larger) army against the Greeks. The Spartan king, Leonidas, and his troops held the Persian forces in place until the Spartans were betrayed by a Greek hired by the Persians into revealing a path that allowed the Persians to surround the Greeks and, finally, overwhelm them. Despite the ultimate defeat of the Spartan force, this delay gave the Athenians enough time to get their navy into position, and they crushed the Persian navy in a single day.
Despite the Persian naval loss, Xerxes’ army was easily able to march across Greece and ransack various poleis and farmlands; it even sacked Athens itself, which had been evacuated earlier. Xerxes then personally withdrew along with a significant portion of his army, while claiming victory over the Greeks. Here, simple logistics were the issue: the Greek naval victory made supply of the whole Persian army impractical.
The next year, in 479 BCE, a decisive battle was fought in central Greece by a Greek coalition led by the Spartans, followed by a Greek naval battle led by the Athenians. The latter then led an invasion of Ionia that defeated the Persian army. Each time the Greeks were victorious, and the Persians finally decided to abandon the attempt to conquer Greece as being too costly. The remaining Greek colonies in Anatolia rose up against the Persians, and sporadic fighting continued for almost 20 years.
While there is obviously a pro-Greek bias to the Greek sources that describe the Persian War, they do identify an essential reason for Greek victories: thanks to the viability of the phalanx, each Greek soldier (from any polis, not just Sparta) was a real, viable soldier. The immense majority of the Persian forces were relatively ineffective peasant conscripts, unwillingly recruited from their homes and forced to fight for a king for whom they had little personal loyalty. The core of the Persian army were excellent cavalry from the Iranian plateau and Bactria (present-day Afghanistan), but those were always a small minority of the total force.
479 BCE was the end of the Persian war and the beginning of the “classical age” of Greece, the period during which the Greeks exhibited the most remarkable flowering of their ideas and accomplishments, as well as perhaps their most selfish and misguided political blunders in the form of a costly and ultimately pointless war between Sparta and Athens: the Peloponnesian War.