The Battle of Thermopylae: How 300 Spartans stood against the massive Persian army

In the early fifth century BC, the Persian Empire was at the height of its power. The Persians had conquered most of Asia Minor and were now eyeing expansion into Europe.

In order to do this, they needed to first deal with the Greek city-states who had supported the Ionian cities in Asia Minor in a revolt against Persia.

The Persians began by targeting Athens, one of the most important Greek city-states.

The Athenians managed to defeat an initial Persian invasion at Marathon in 490 BC.

Following the defeat at Marathon, the Persian king Darius died in 486 BC and was succeeded by his son, Xerxes.

Xerxes was determined to complete his father's work and crush the Greeks once and for all.

In 481 BC, he assembled the largest army that had ever been seen and set out to conquer Greece.

The Persian army, which was led by King Xerxes himself, arrived in 480 BC and invaded Greece by crossing the Bosphorus Strait and marching south towards Athens.

When news of the Persian invasion spread, the various city-states quickly banded together in an alliance led by Sparta.

The Spartan king Leonidas was chosen to lead the Greek army against the Persians. 

When word of the oncoming army reached Greece, the first move was for around 8,000 hoplites to take up position at the Vale of Tempē near Mt Olympus, where they hoped to engage with the invaders.

However, when it became apparent that the approaching Persian force was significantly larger than the combined Greek forces, they retreated southward to find a better location for the battle.

Eventually, Leonidas chose to make his stand at a place called Thermopylae. It was a strategically beneficial location, because the Persians had to travel along a road through this region in order to get to Athens.

In particular, at Thermopylae, the road became a narrow pass that was bordered by steep mountains on one side and the sea on the other.

So, for 1.5 kilometres, the Persian army would become vulnerable, as they had to march in a narrow line, sometimes no wider than a wagon.

This limited space would allow the Greeks to nullify the Persian numerical advantage and especially their cavalry.

Also, the Greeks repaired an old wall halfway along the pass that would further obstruct the Persian army's ability to advance along the road.

Even at this planning stage, Leonidas appears to have not expected a Greek victory against the Persians but may have simply hoped to slow their advance in order to give the Greek cities in the south time to evacuate to safety.

Since they expected to eventually lose, the Greek force at Thermopylae was reduced to around 6000 men, including 300 Spartans, 1,120 Arcadians, 1,000 Lokrians, 1,000 Phocians, 700 Thespians, 400 Corinthians, and 400 Thebans, plus others. The rest of the Greek soldiers were allowed to return home.

The Spartans had the fewest troops of all the different contingence, with only 300 hoplites.

This may be due to the fact that they already knew the fight would be end in defeat and only wanted soldiers who had living sons who could replace them after their deaths.

The Greek cities also sent a fleet of ships to the coast of Artemesium on Euboea's northern coast, 40 nautical miles from Thermopylae.

Their main goal was to prevent the Persian navy from sailing down the coast towards Athens.

The Persian army was a truly massive force. The exact number of Persian soldiers is a matter of historical debate, with the ancient Greek historian Herodotus claiming that it was 2 million strong.

However, modern estimates are much lower, generally around 100,000 to 150,000.

Regardless, the core of the army was made up of Immortals, which was an elite group of soldiers who were hand-picked by the king and given special training.

Aside from them, the regular Persian infantry was armed with short spears and wicker shields, while the cavalry was armed with bows and lances.

However, Persian war tactics usually relied upon an initial volley of arrows to do as much damage to enemies as possible before sending a huge number of infantry in waves to overwhelm the remaining defenders.

What the Persians didn't know is that the heavy hoplon shields used by the Greeks were large and thick enough to negate the effectiveness of the arrows, while the restricted space created by the narrow path reduced any benefit of larger numbers of soldiers.

In the summer of 480 BC, the Persian army arrived at Thermopylae and demanded that the Greeks surrendered.

Leonidas refused, and the battle began. On the first day, the Persians advanced against the Greeks as normal, but they were quickly pushed back by Leonidas and his men. 

The Persian army was frustrated that it was unable to break through the Greek defenses, especially when they suffered heavy casualties.

This was primarily due to the differences between the infantry types on both sides.

The Greek hoplites were heavy infantry, armed with long spears and heavy shields, while the Persians were light infantry, armed with short spears and wicker shields.

On the second day of battle, Xerxes became impatient and ordered his troops to attack again. The Persians were again unable to break through the Greek defenses. 

So, Xerxes consulted with his generals and decided to send in his elite Immortals instead. They were considered to be some of the best warriors in all of Persia. 

However, the Immortals were no more effective than the previous Persian troops.

Despite their better training, they were armed with the same weapons and armour as regular troops, so were unable to cause significant numbers of Greek casualties.

As a result, the second day of battle ended with little progress being made by the Persians and increasing numbers of deaths among their troops.

On the evening of the second day, a local Greek man named Ephialtes came to the Persian camp and offered to show Xerxes' soldiers a way around the narrow pass.

The Persian king was understandably hesitant, but he eventually agreed. That night, Ephialtes led a group of Persian soldiers through a secret path that went around the narrow pass. 

It must be stated that Leonidas had been aware of this mountain path, and he had sent the 1000 Phocians to keep watch over it.

However, even though the Phocians put up a fight against the Persian soldiers, they were quickly outflanked and forced to retreat. 

Finally, by daybreak, the Persian force arrived behind the Greek line and prepared to attack them from the rear.

When Leonidas was made aware of this development, he ordered the majority of the Greek soldiers to leave if they wanted to, which many did.

However, he stayed behind with 300 Spartans to hold off the Persian army and buy the retreating Greeks as much time as possible.

The Thespians, Thebans, and probably the 2000 helots also chose to stand and fight to the end with the Spartans.

By dawn on the third day of battle, the small force of Persians that had been able to flank the Greeks were ready to attack.

As a consequent, the Spartans were then assaulted from the front and from behind by the Persian army.

Nevertheless, the remaining Greeks were determined to fight to the death and cause as many casualties as possible.

So, the Greeks charged out of the pass and met the Persian forces head-on, which they thought was the best way to maximise the number of enemies they could kill. 

According to Herodotus, they fought with their spears until they were all shattered, and then continued to fight with their short swords. 

In these early stages, Leonidas himself was killed in action and the Greeks attempted to recover his body.

However, when the Persian Immortals advanced, the remaining Greeks had to retreat to a nearby hill where they prepared to make their last stand.

It was at this time that the remaining Thebans chose to surrender to the Persians, but the other Greeks did not.

Seeing his remaining enemies trapped on a hill with nowhere to flee, Xerxes decided to avoid the huge death tolls from the previous days.

He ordered his Persian archers to fire successive volleys of arrows until the last of the Greeks were killed. 

While Xerxes finally achieved his victory, it cost him a great deal. Historians estimate that the Greeks suffered around 2,000 casualties at Thermopylae, while Persian casualties ranged from 20,000 to 30,000.

With the death of the last Greek defender, Xerxes ordered that the defensive wall at Thermopylae to be torn down, and he continued his march towards Athens.

While the Battle of Thermopylae was a resounding Persian victory, it was not the only one occurring at that time.

In fact, a key naval battle was also taking place between the Persians and the Greeks.

The Greeks had already sent their navy to block the narrow straits at Artemisium in order to prevent Xerxes' huge fleet of around 700 ships supplying the land army with food and water. 

In comparison, the Greeks had a fleet of around 270 triremes under the command of the Spartan admiral, Eurybiades, and the Athenian commander, Themistocles. 

Prior to the battle, in a stroke of luck for the Greeks, the Persians had lost around 400 ships in two successive storms along the coast of Euboea.

Luckily. the Greeks were protected from these storms, as they were sheltered in harbours.

When the two fleets finally fought each other over three days, neither side was able to gain an advantage.

By dusk on the third day, both sides had suffered roughly the same number of losses.

As a result, a council of war was held among the Greeks to decide what to do. At the meeting, news was received about Leonidas' death and the defeat at Thermopylae. 

So, the Greek commanders decided that there was nothing more to be gained at Artemisium and they retreat back to Athens that night.

The Battle of Thermopylae was a significant military victory for Persia. However, it was not the crushing victory that Xerxes had hoped for.

The Persian army was delayed just long enough for the Greeks to prepare their defenses at the narrow pass at Corinth and to evacuate the people from the city of Athens. 

Kleombrotos, Leonidas' brother, took over command of the Spartan army and prepared to defend the isthmus of Corinth from an expected Persian attack. But, this never eventuated.

For his part, Themistocles, had prepared Athens for war by using his fleet to ship the Athenians to the island of Salamis, across the bay from the city.

Xerxes' army reached Athens shortly after the retreating Greek navy departed.

He found that the city was defended by a small number of remaining men and, as was to be expected, was quickly captured by the Persians.

As a way of punishing the Greeks, Xerxes ordered that the city of Athens was to be promptly burnt to the ground.

Although they had been defeated at Thermopylae, the Greeks went on to defeat Xerxes' army at Salamis later that year.

This victory was a turning point in the war, and ultimately led to the Greeks defeating the Persians at the Battle of Plataea in 479 BC.