Simultaneous with the land battle at Thermopylae, a sea battle took place near Artemisium at the Northwest corner of Euboea. The Greek allies were attempting to block the Persian Fleet using the same tactic as Leonidas’ attempt to block Xerxes’ Army at Thermopylae. The Greeks saw their army and navy as coordinated elements that would communicate to each other about the success of each mission, so they designated a fast ship to carry messages between them. Greek fleet was commanded by the Spartan Eurybiades and the future Athenian hero Thermistocles.
After losing 400 ships in storms, the Persians struggled to keep their fleet together but were finally able to anchor at Aphetae at the Southeast point of Thessaly. The Greeks located themselves across the Straight of Artemisium so they could block Persian path to Phocis and Boetia. In an initial skirmish on the first day, the Greeks were able to capture 30 Persian ships. Stung by the defeat at the hands of such a small force, the Persians put a larger battle fleet together and fought the Greeks to a draw on the third day. The Greeks could not afford a draw because they had fewer ships, so they were considering a withdrawal when they heard about the military defeat at Thermopylae. They retreated back to Salamis, leaving the door open to a Persian invasion of Attica.
Xerxes invited his sailors and commanders to visit Thermopylae to witness the victory of his army, but not before he had twenty thousand dead Persians buried to make the losses look more even.
Later the Spartans sent an envoy to Xerxes asking for payment as compensation for the way Leonidas body was desecrated after his death. Xerxes laughed, stating that his general Mardonius would deliver the Persian reply to the request when he destroyed Greece during the next year’s campaign. Of course, the next year Mardonius was killed at the Battle of Platea, which ended Persian attempts to conquer Greece.