The narrow pass of Thermopylae was held for three days against a vast Persian army by just 300 Spartans, 299 of which perished.
Although there were 300 Spartans present at the defense of Thermopylae, there were at least 4000 allies involved on the first two days and 1500 men involved in the fatal last stand. Still a tiny figure compared to the forces against them, but more than the legend which forgets some contributors.
Having raised a vast army operating on the limits of supply and command – perhaps 100,000 strong – the Persian King Xerxes invaded Greece in 480 BCE intent on adding the city states to an Empire which already spanned three continents. The Greeks responded by putting aside traditionally enmity, allying and identifying a place to check the Persian advance: the land pass of Thermopylae, already fortified, was just forty miles away from a narrow sea strait between Euboea and the mainland. Here smaller Greek forces could block the armies and fleet of the Persians at the same time and hopefully protect Greece itself.
The Spartans, a brutal people with arguably the most militaristic culture in history (Spartans could only reach manhood once they’d killed a slave) agreed to defend Thermopylae. However, this agreement was given in the first half of 480 and, as the Persians advanced proceeded inorexibly but leisurely, months passed. By the time Xerxes had reached Mount Olympus it was August.
This was a bad time for the Spartans, for they were to hold both their Olympics and Carneia. To miss either was to offend the Gods, something the Spartans cared passionately about. A compromise was needed between sending a full army and keeping their divine favor: an advance guard of 300 Spartans, led by King Leonidas would go. Instead of taking the Hippeis, his 300 strong bodyguard of the best young men, Leonidas departed with 300 veterans.
There was a little more to the compromise. The Spartan 300 weren’t supposed to be holding the pass by themselves; instead their absent army would be replaced by troops from other states. 700 came from Thespiae, 400 from Thebes. The Spartans themselves brought 300 Helots, basically slaves, to assist. At least 4300 men occupied the pass of Thermopylae to fight.
The Persian army did indeed arrive at Thermopylae and, after their offer of free passage to the Greek defenders was refused, they attacked on the fifth day. For forty-eight hours the defenders of Thermopylae held out, defeating not just the poorly trained levies sent to dull them, but the Immortals, the Persian elite. Unfortunately for the Greeks, Thermopylae held a secret: a small pass by which the main defences could be outflanked. On the sixth night, the second of the battle, the Immortals followed this path, brushed aside the small guard and prepared to catch the Greeks in a pincer.
King Leonidas, undisputed head of the Greek defenders, was made aware of this pincer by a runner. Unwilling to sacrifice the entire army, but determined to keep the Spartan promise to defend Thermopylae, or perhaps just act as a rearguard, he ordered everyone bar his Spartans and their Helots to retreat. Many did, but the Thebans and Thespians stayed (the former possibly because Leonidas insisted they stay as hostages). When battle commenced the next day there were 1500 Greeks left, including 298 Spartans (two having been sent on missions). Caught between the main Persian army and 10,000 men to their rear, all were involved in fighting and wiped out. Only Thebans who surrendered remained.
It is entirely possible the above account contains other myths. Historians have suggested the full force of Greeks may have been as high as 8000 to begin with or that the 1500 only stayed put on the third day after being trapped by the Immortals. The Spartans may have only sent 300, not because of the Olympics or Carneia, but because they didn’t wish to defend so far north, although it does seem unusual they would have sent a King if so.
Persian Fire by Tom Holland (Little Brown, 2005)
The Battle of Thermopylae: A Campaign in Context by Robert Oliver Matthews (Spellmount 2006)
The Defence of Greece by J. F. Lazenby. (Aris & Phillips 1993)