Thebes contributed 400 hoplites to the Greek force at Thermopylae. The contingent was commanded by Leontiades and formed part of the coalition resisting Xerxes’ invasion of Greece in 480 BC.
The Theban contingent had an unusual political background. Thebes and much of Boeotia had already shown signs of submission to Persia, so Leonidas was suspicious of their loyalty. According to the traditional account, the 400 Thebans were kept with the Greek rearguard after other allied troops withdrew, effectively ensuring that they could not simply leave the battlefield.
The figure is easy to confuse with other Thermopylae numbers: 300 Spartan citizens, 700 Thespians, and approximately 1,000 Phocians are among the better-known contingents. The 400 Thebans were present during the final stand, but Herodotus says that most eventually surrendered to the Persians, unlike the Spartans and Thespians who fought to the death.