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On the plain of Marathon in 490 BCE, an Athenian-led army faced an expedition sent by Darius I, king of the Achaemenid Persian Empire. The battle is one of antiquity’s most famous confrontations—and one of the most often assigned to a modern calendar date. September 12 appears in reference works, commemorations and timelines. Yet no participant recorded “September 12” in the calendar we use today.
The event is secure; the conversion is not. Ancient evidence places the battle in the Athenian year and connects it with Spartan religious observance. Later scholars reconstructed the date by matching Greek lunar calendars to astronomical cycles. September 12, 490 BCE is a widely used traditional answer, but other reconstructions have proposed dates in August or later in September. For a site organized by calendar date, that uncertainty is part of the history—not a reason to hide it.
Why Persia came to Marathon
The conflict grew from the Ionian Revolt, in which Greek cities on the western coast of Anatolia rebelled against Persian rule. Athens and Eretria provided limited support to the rebels and took part in the attack on Sardis. Persia suppressed the revolt. Darius then moved to punish Athens and Eretria and to extend Persian control across the Aegean.
In 490 BCE, a Persian expedition commanded by Datis and Artaphernes crossed the Aegean. Eretria fell after a siege. The fleet then sailed to the bay of Marathon in north-eastern Attica. The broad coastal plain offered space for disembarkation and access toward Athens. Hippias, the exiled former tyrant of Athens, accompanied the expedition and could advise the Persians on local terrain and politics.
Athens mobilized its citizen hoplites and appealed to Sparta. According to Herodotus, the runner Pheidippides covered the route to Sparta, where officials said religious law prevented them from marching before the full moon. The small city of Plataea sent troops to support Athens. The Athenians and Plataeans took position near the plain while the Persian force remained close to its ships.
What the sources can—and cannot—show
Herodotus, writing several decades later, is the principal surviving narrative source. He describes the strategic setting, the Athenian debate over whether to fight and the course of the battle. His account is indispensable, but it is not a modern after-action report. Speeches in ancient histories often express an author’s interpretation, and reported numbers can be schematic or exaggerated.
Archaeology adds physical anchors. The burial mound of the Athenians, objects associated with the battlefield and the shape of the Marathon plain help scholars test literary accounts. They cannot recreate every movement. Even the location of the Persian camp, the role of cavalry and the precise reason the Athenians attacked when they did remain debated.
That gap matters for narrative. It is reasonable to describe the plain, the bay, the armies’ equipment and the decisions reported by Herodotus. It is not responsible to invent a minute-by-minute sequence, exact weather, shouted dialogue or the thoughts of Miltiades and the ordinary hoplites.
The Athenian advance
The Athenian commanders accepted battle. Herodotus gives a central role to Miltiades, one of the ten generals, and says the polemarch Callimachus supported the decision. The line was arranged with stronger wings and a comparatively thinner center, extending the front to reduce the danger of being outflanked.
Herodotus says the Greeks advanced at a run over the distance separating the armies. Modern historians debate how far and how continuously they ran, especially under the weight of a hoplite’s shield and equipment. The underlying tactical purpose is easier to understand: the Athenians needed to close with Persian archers and bring heavily armed infantry into close combat.
The Persian center pushed back the thinner Greek center. On the wings, however, Athenians and Plataeans prevailed, then turned inward against the Persian troops who had advanced in the middle. The formation was not a magical device; it was a risky deployment that became effective as the two wings maintained cohesion and exploited their success.
The fight at the ships
The defeated Persian force withdrew toward the shore and its vessels. Fighting continued around the ships. Herodotus records that the Athenians captured seven vessels and names prominent losses, including Callimachus. His casualty totals—192 Athenians and 6,400 Persians—have shaped memory of the battle, but the Persian figure cannot be independently verified and should not be treated as a precise modern count.
The surviving fleet did not simply disappear. It sailed around Cape Sounion, apparently threatening Athens from another direction. The Athenian army returned rapidly to the city. When the Persian fleet approached, it found an organized defense and withdrew. Marathon was therefore more than the clash on the plain; it included the race to prevent the expedition from exploiting the army’s absence.
The famous story of a messenger running from Marathon to Athens, announcing victory and dying, is not in Herodotus’s account. Later authors preserve versions involving different runners and routes. The modern marathon race drew on that later tradition, while Herodotus’s documented long-distance runner traveled from Athens to Sparta before the battle.
A victory with limits
Marathon blocked the Persian expedition’s immediate objective and gave Athens an extraordinary political and cultural memory. The victory demonstrated that a Persian force could be defeated in a set battle. It did not end the Persian threat. Ten years later, Xerxes led a much larger invasion of Greece, producing the battles of Thermopylae, Salamis and Plataea.
Later Athenians made Marathon central to their civic identity. The dead were buried on the battlefield, an exceptional honor. Painted and sculpted commemorations presented the victory as a defense of the city and its political order. In the centuries that followed, Marathon became a symbol onto which writers projected arguments about liberty, empire, East and West. Those claims often say more about later societies than about 490 BCE.
So did the battle happen on September 12?
September 12 is best described as a traditional reconstructed date, commonly equated with the sixth day of the Athenian month Boedromion. The conversion depends on assumptions about local lunar calendars and on how the Spartan festival mentioned by Herodotus was dated. Because Greek city-states did not all use an identical calendar, a one-month difference in the reconstruction can move the battle into August. Other scholarship has proposed still different dates.
The honest conclusion is precise about the limits of precision: the Battle of Marathon occurred in 490 BCE and ancient evidence establishes its historical context, but its exact equivalent in the modern calendar remains disputed. September 12 deserves a place in “Today in History” because it is the traditional commemoration—not because a surviving ancient document supplies that date.
Explore the September 12 edition: return to Today in History – September 12, browse the Ancient History archive, read how the Persian Wars entered drama in Aeschylus’s Persians, or compare Marathon with the first battle described in extensive written records.
Sources and method
The account uses Herodotus, Book 6, available through the Perseus Digital Library, together with material evidence such as the lead sling bullet from Marathon in the British Museum. The date discussion follows modern calendar-reconstruction scholarship, including Jan P. Stronk’s review in Talanta. Where ancient testimony and modern reconstruction diverge, the article identifies the uncertainty rather than choosing a false certainty. No dialogue or private thoughts have been invented.
