Thermopylae & Salamis: The Real 480 BCE Campaign

Military History: The Greeks

Chapter 5 · Thermopylae & Salamis: The Real 480 BCE Campaign

Chapter 4 covered the first Persian invasion's own defeat at Marathon in 490 BCE. Ten years later, Xerxes I returned with a far larger force, and this chapter covers the campaign's two defining engagements — a land battle remembered mostly as legend, and a naval battle that actually decided the war.

Thermopylae: A Real Force Much Larger Than "300"

In August 480 BCE, a Greek force blocked the narrow coastal pass at Thermopylae against Xerxes's advancing army. Popular memory reduces this force to "the 300 Spartans" — but the real, documented Greek army was considerably larger.

The Real Composition of the Greek Force Leonidas commanded roughly 7,000 hoplites in total: 300 Spartiates plus their helot attendants (who likely fought as light infantry), alongside 500 from Tegea, 500 from Mantinea, 1,000 from the rest of Arcadia, 400 from Corinth, 700 from Thespiae, 400 from Thebes, and contingents from Phocis and Opuntian Locris, among others. The "300 Spartans" framing badly understates the real, genuinely multi-city Greek defense.

Persian numbers remain genuinely disputed — ancient sources claim figures as high as 300,000, while modern estimates place Xerxes's real force somewhere between 80,000 and 200,000. Whatever the true number, it vastly outnumbered the Greek defenders.

The Narrow Pass

Thermopylae's own narrow terrain — mountains on one side, sea on the other — neutralised the Persian numerical advantage, forcing combat onto a front only a small force needed to hold.

Ephialtes's Betrayal

On the third day, a local Greek named Ephialtes revealed a mountain path allowing Persian forces to outflank the defenders — the real, decisive turning point of the battle.

The Last Stand

Once outflanked, Leonidas dismissed most of the army but held his ground with the Spartans, Thespians, and Thebans, fighting to the death to cover the retreat of the rest.

Salamis: The Real Decisive Battle

Thermopylae bought time, not victory — Athens itself was evacuated and burned. The war's real outcome was decided weeks later, at sea, in the narrow strait between the island of Salamis and the Greek mainland.

Themistocles's Real Tactical Deception Themistocles sent a secret message to Xerxes claiming the Greek fleet intended to retreat, deliberately luring the far larger Persian navy into the narrow Salamis strait rather than letting it fight in open water, where Persian numbers would have told decisively.

Real ship numbers again vary by source: the Greek fleet is generally put around 300–370 triremes against a Persian force of roughly 800 (some ancient sources claim up to 1,000). In the confined strait, the Persian numerical advantage became a genuine liability — larger ships had no room to maneuver and collided with one another, while the more agile Greek triremes exploited the chaos. The Greeks sank roughly 300 Persian vessels while losing only around 40 of their own, a real, decisive naval victory that broke Xerxes's own ability to supply his invasion and forced much of his army to withdraw.

Looking Ahead

Chapter 6 covers the Athenian navy in greater technical depth — the trireme itself, and Themistocles's own real role building the fleet that made Salamis possible.

Reflect

Question 1 The real Greek force at Thermopylae numbered roughly 7,000, not 300. Why might popular memory compress a genuinely multi-city defense down to a single, smaller, more dramatic number?
Question 2 Thermopylae ended in a real Greek defeat, yet it's remembered as a heroic triumph, while Salamis actually won the war but receives comparatively less popular attention. What might explain this gap between military significance and cultural memory?
Question 3 Themistocles won at Salamis partly through deliberate deception rather than raw force. What does this suggest about the role of psychological and strategic tactics alongside pure combat strength in ancient naval warfare?

Chapter 5 Quick Reference

  • August 480 BCE: Thermopylae — a real ~7,000-strong multi-city Greek force, not "300 Spartans" alone
  • Ephialtes: The Greek traitor whose real betrayal via a mountain path decided the battle
  • Leonidas's last stand: Spartans, Thespians, and Thebans held the rear guard after the main army withdrew
  • September 480 BCE: Salamis — Themistocles lures the larger Persian fleet into a narrow strait
  • Real outcome: ~300 Persian ships sunk against ~40 Greek losses — the war's own real decisive battle