Battle of Thermopylae - King Leonidas I vs Xerxes I. Persian invasion of Greece Sparta.

The Battle of Thermopylae (/θərˈmɒpɪliː/ thər-MOP-i-lee; Greek: Μάχη τῶν Θερμοπυλῶν Máchē tōn Thermopylōn; Persian: نبرد ترموپیل Nâbārd-e Ṭermopīl) took place during the second Persian invasion of Greece. Occurring in July, August, or September 480 BC, it was one of the most prominent military engagements of the Greco-Persian Wars. Seeking to halt the Persian army's offensive into Greece, an alliance of Greek city-states was led by Sparta to block off Thermopylae. After three days of fighting, the Spartan king Leonidas I was killed and the rest of the Greeks were outflanked and annihilated, enabling the Achaemenid Empire to take control of Phocis, Boeotia, and Attica.