The 10,000 soldiers who could never truly die

Wars & Conflicts · Published 9 October 2026 Swipe more like this →

In short: To the Greeks, the Achaemenid Empire possessed a terrifying, invincible force known as the Immortals. Their secret wasn't magic, but a relentless system of immediate replacement. By ensuring their elite corps always maintained a constant strength of 10,000 men, the Persians projected an image of invulnerability on the battlefield.

The Immortals were an elite heavy infantry unit serving the Achaemenid kings, acting as both an imperial guard and a professional standing army. While the name 'Immortals' comes from the Greek historian Herodotus, it is unclear if this was their actual Persian designation. Some scholars suggest Herodotus may have confused the word for 'companion' with the word for 'immortal', though this theory is contested by linguists.

In combat, these soldiers were highly versatile. They utilized a combination of ranged weaponry, such as bows and arrows, and close-quarter tools, including short spears and the Acinaces sword. Their defensive gear included scale armor and large wicker shields covered in leather, which could be planted in the ground for cover. To denote rank, common soldiers carried silver spear butt-spikes, while officers carried gold ones.

The unit's presence was a psychological weapon as much as a military one. By immediately replacing any soldier who died, fell ill, or was wounded, the corps maintained a fixed strength of exactly 10,000 men. This consistency helped the Achaemenids in major historical milestones, including the conquest of Babylon in 539 BCE, the conquest of Egypt in 525 BCE, and the famous Battle of Thermopylae in 480 BCE.

The legacy of this unit is so potent that the term 'Immortal' has been used by various empires throughout history, from the Sasanian and Byzantine Empires to Napoleon's Imperial Guard. Even in modern times, the last Shah of Iran established the Javidan Guard, or 'Immortal Guard', to honor this ancient Persian military tradition.

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