The Battle of Thermopylae, which took place in 480 BCE during the second Persian invasion of Greece, is one of the most famous battles in ancient history. While the precise dates are uncertain, sources suggest that the three-day battle took place either from 21 to 23 July or from 8 to 10 September in the year 480 BC. The primary source for our knowledge of this battle is the account given by the ancient Greek historian Herodotus in his work The Histories, written about 40 years after the battle.

Herodotus records that Persian King Xerxes I commanded an enormous army, believed to number between 100,000 and 250,000 soldiers, in his campaign against Greece. In response, the Greeks, anticipating the invasion, dispatched a contingent of around 7,000 warriors, under the leadership of Spartan King Leonidas I, to guard the strategic pass of Thermopylae, the principal gateway to central Greece.

The terrain of Thermopylae was crucial to the Greeks' strategy. The narrow pass, flanked by mountains on one side and the sea on the other, allowed a small force to hold off a much larger army. This gave the Greeks an advantage as they chose to fight defensively, utilizing their superior training and equipment to defend against the Persian onslaught. The battle itself lasted for three days. On the first day, Xerxes sent his Median and Kissian troops to attack the Greeks, but they were repulsed with heavy losses. On the second day, Xerxes sent his elite Persian Immortals to attack, but they too were unable to break through the Greek defenses.

On the third day, a local named Ephialtes betrayed the Greeks by revealing to the Persians a path that led behind the Greek lines. Leonidas, understanding that his position had become indefensible, sent away the majority of the Greek army and stayed with 300 Spartans, 700 Thespians, and 400 Thebans, choosing to fight to the death to hinder the Persian advance. In terms of military strategy, the Greeks used the narrow pass of Thermopylae to their advantage. By positioning themselves at the narrowest point of the pass, they were able to negate the numerical superiority of the Persian army and force them into a frontal assault. The Greeks also used their superior armor and training to great effect, with the Spartans in particular being renowned for their martial prowess.

The Persians, on the other hand, relied on their numerical superiority and the diversity of their troops, which included contingents from many different nations within the Persian Empire. They also used cavalry and archers to try to weaken the Greek defenses, although these tactics were largely ineffective due to the terrain. Despite the ultimate Greek defeat, the Battle of Thermopylae had a significant impact on the course of the war. The bravery and sacrifice of the Greeks, particularly the Spartans, inspired the other Greek city-states to unite against the Persian threat. The battle also bought valuable time for the Greeks to prepare their defenses and ultimately defeat the Persians at the battles of Salamis and Plataea.

Bibliography:

Bauer, Susan W. The History of the Ancient World: From the Earliest Accounts to the Fall of Rome. New York: W. W. Norton & Company, 2007.

Strassler, Robert B., editor. The Landmark Herodotus: The Histories. New York: Anchor Books, 2009.