A group of infantrymen from within the Persian Empire which, in 401 BCE, included Egypt, Georgia, Pakistan, and the Dardanelles (part of modern-day Turkey). The Immortals got their name from the fact that their number was never supposed to be lower than 10,000 standing soldiers. Those who died became too injured to fight, or were too old and were replaced by younger and healthier recruits. The Immortals also guarded the royal palace at Persepolis. Caputo mentions them in the context of military historians’ comparison of the Chosin campaign in the Korean War with the “march of Xenophon’s Immortals.” Any Marine, such as William Campbell, who claimed to have been at Chosin was regarded with as much respect as one of Xenophon’s Immortals might have been.