Your guide to the battle of Thermopylae

The battle for the pass

As you approach Thermopylae (about 200 kilometres from modern Athens) from the north, the mountains loom before you like a wall. At the time of the invasion the view was more daunting still. Changes in the sea level mean that these days, the hills at Thermopylae now skirt an alluvial plain [a mainly flat landform]. But in 480 BC, the sea washed up to the base of steep hills and the pass was narrow: five metres wide at most at each end, and no more than 15 metres even in the middle.

The opposing Greek force was small, not much more than 7,000, with 300 Spartans at its core. But it was stuck like a cork in a bottle. To advance south, Xerxes had to take the pass – and time was not on his side. It was late summer, and he needed to wrap up the whole invasion as far as possible before winter. His army was vast: ancient sources put its numbers in the millions, although modern historians incline to about 200,000. Even 50,000 would have been huge by ancient standards. Xerxes knew that if he delayed, he faced supply problems. He needed to feed and water not just the warriors but a host of camp followers, cavalry mounts and baggage animals – plus an immense and lavish royal retinue. So, he was under pressure.

• Read more: Were there really only 300 Spartans at the battle of Thermopylae?

The Greeks were heavily outnumbered. But the tight space meant that the Persians could not use their vast numbers to crush them. And they could not use the tactics that had made them masters of the world from the Aegean to the Indus: breaking the enemy with volley after volley of arrows from a distance, before moving in to annihilate them. Xerxes’s force instead had to resort to the brutal hacking clash of infantry lines at close quarters: the Greek way of fighting. Worse still, the sheer numbers of the Persian force counted against them, since in this confined space they were at constant risk of being crushed by their own side.

For two days, Xerxes threw division after division into the pass. All came back mauled – even his elite corps of 10,000 ‘Immortals’. But there were paths through the hills, and one in particular led along the mountain overlooking the pass to a point behind the Greek lines. Alerted to the path by a local Greek, at dusk on the second day Xerxes sent his Immortals to prepare to outflank the Greeks on the morning of day three.

This week is Ancient Greece Week on HistoryExtra!

Join us as we explore one of the world’s greatest civilisations – from the birth of democracy and the ancient Olympics to warfare, the rights of women and the whims of the gods.

Take me to today's highlights

Surrounded by the enemy

When Leonidas learned of the encirclement early on the third day, he called a meeting. They still had time to withdraw, but Leonidas and what was left of his 300 Spartans insisted on staying. So, too, did the contingent of 700 from the ancient Greek city of Thespiae. Since their city in the nearby region of Boeotia was in the path of any Persian advance, they had good reason to lay down their lives. Four hundred Thebans also stayed (only to desert at the end).

Leonidas needed a rear-guard to hold back the Persians – and die, if necessary...

The rest of the Greek force chose to leave. The historian Herodotus, keen to lionise Leonidas, tells us that the leader sent the allies away to spare their lives and win immortal glory. Although neither motive can be dismissed, it’s likely that the main reason was strategic. The Persians (unlike the Greeks) had cavalry, which could overtake and destroy the retreating forces. To buy time for the retreating troops, Leonidas needed a rear-guard to hold back the Persians – and die, if necessary.

• Read more: 9 of the most overrated battles in history (and one underrated one)

The rear-guard held their own, despite losing their commander Leonidas amidst brutal, drawn-out fighting . But then the Immortals arrived, and the Greeks had to retreat to a low hill. The vicious hand-to-hand fighting had broken their spears and swords, but they fought on with daggers, hands and teeth until the Persians tired of unnecessary losses and shot them down with arrow volleys. Arrowheads of Anatolian design have been found in large numbers on the hill by modern archaeologists.

Thermopylae was a Greek defeat. The rear-guard was annihilated and the Persians rolled on to occupy central Greece. But Thermopylae did – crucially – prove that the Persian war machine could be stopped. It also tested the Greek strategy of using confined space to neutralise Persian numbers, a strategy that later proved devastatingly effective when the Greeks destroyed the Persian fleet in the narrow strait of Salamis just a month or so later.

• Read more: The ancient Greeks at war: hoplites, the phalanx and the greatest battles

Where does the myth of 300 Spartans come from?

Win or lose, the battle achieved mythic status almost at once, like the British retreat at Dunkirk in 1940, or the massacre of the defenders at the Alamo mission in Texas in 1836. And it became Sparta’s myth. The 300 Spartans were a minority of the defending force – not just in the army but even in the last stand – but the clash became the battle of the Spartan 300, not the Greek 7,000, in popular imagination.

It was Thermopylae that created the myth that Spartans always win or die...

It also served to polish Sparta’s already formidable reputation for invincibility. In the fifth century BC, Herodotus recounts how Xerxes (before Thermopylae) asked the exiled Spartan king Damaratus how free Greeks could stand against him without being forced to fight under the lash. Damaratus replied that the Spartans, though free, have a master whom they fear more than the Persians: their king and the law, which tells them not to retreat, but to stand and die. This wasn’t strictly true; the Spartans knew how to retreat. It was Thermopylae that created the myth that Spartans always win or die.

Equally useful for Sparta’s image were stories of Spartans who made the mistake of surviving. One such story is that of Aristodemus, who was one of two Spartans invalided out of the battle due to an eye infection. His comrade, Eurytus, was blinded –but he returned to the battle to fight and die. Aristodemus, meanwhile, went home. He was ostracised and his life was made so unbearable that he preferred to die as a berserker fighting against the Persians a year later. The Spartans still refused to forgive him, even then. The message was clear: no second chances in Sparta.

Later sources present the whole campaign as a suicide expedition...

Most strikingly, later sources present the whole campaign as a suicide expedition, having Leonidas tell the authorities at Sparta before the battle that his real goal is to die for Greece. But 7,000 seems a large force to send out just to die for no strategic goal. And the story works only for the 300 Spartans, not the 6,000+ allies. Certainly, those who left on the third day did not think they had joined a suicide squad. The story reflects the tendency we all have to ‘read history backwards’ and see the outcome as both inevitable and predictable. It usually isn’t.

Thermopylae also generated proliferating stories of Spartan courage under fire, always tied to the Spartan reputation as ‘men of deeds’ not words. The Spartan soldier Dieneces, when told that the Persian arrows would blot out the sun, is said to have replied calmly: “Good news; we’ll be fighting in the shade.” A later story adds to this reputation: when the Persians demanded that the Spartans hand over their weapons, Leonidas answered “Come and get them” (words now inscribed on his statues in Sparta and at Thermopylae).

• Read more: A brief history of sex and sexuality in Ancient Greece

Thermopylae became the archetype for the courageous last stand. In modern times, it has been used and abused as the yardstick for courageous sacrifice against the odds. It has been used to glorify genuine tales of courage – such as the stand of the Indian and British forces at Kohima, in north-east India, against the Japanese invasion in the Second World War, or the courageous action of the passengers of United Airlines Flight 93 on 9/11 against the terrorists who hijacked the plane (the aircraft crashed in a field, prevented from reaching its intended target).

Also, ironically, Thermopylae has been used to glorify imperialist failures – such as the defeat at Dien Bien Phu in Vietnam in 1954 during the closing years of French control in Indo-China, or the British defeat by the Zulus at Isandlwana in KwaZulu-Natal in 1879. It was invoked, too, at the catastrophic German failure at Stalingrad during the German invasion of Russia in the Second World War.

There’s no doubt that the events of Thermopylae in 480 BC live on, in our history, our popular culture and beyond.

• Read more: Famous Greeks – 14 influential figures from the ancient Greek world

Chris Carey is Emeritus Professor of Greek at University College London. He is the author of Thermopylae, part of the Great Battles series, published by Oxford University Press in August 2019