The Battle of Salamis was a naval battle fought in 480 BC, between an alliance of Greek city-states under Themistocles, and the Achaemenid Empire under King Xerxes. It resulted in a victory for the outnumbered Greeks.
Background
The Greek city-states of Athens and Eretria had supported the unsuccessful Ionian Revolt against the Persian Empire of Darius I in 499-494 BC, led by the satrap of Miletus, Aristagoras. The Persian Empire was still relatively young, and prone to revolts amongst its subject peoples. Moreover, Darius was a usurper, and had spent considerable time extinguishing revolts against his rule. The Ionian revolt threatened the integrity of his empire, and Darius thus vowed to punish those involved (especially those not already part of the empire). Darius also saw the opportunity to expand his empire into the fractious world of Ancient Greece. A preliminary expedition under Mardonius, in 492 BC, to secure the land approaches to Greece ended with the conquest of Thrace and forced Macedon to become a client kingdom of Persia.
In 491 BC, Darius sent emissaries to all the Greek city-states, asking for a gift of 'earth and water' in token of their submission to him. Having had a demonstration of his power the previous year, the majority of the Greek cities duly obliged. In Athens, however, the ambassadors were put on trial and then executed; in Sparta, they were simply thrown down a well. This meant that Sparta was also now effectively at war with Persia.
Prelude
The Allied fleet now rowed from Artemisium to Salamis to assist with the final evacuation of Athens. En route Themistocles left inscriptions addressed to the Ionian Greek crews of the Persian fleet on all springs of water that they might stop at, asking them to defect to the Allied cause. Following Thermopylae, the Persian army proceeded to burn and sack the Boeotian cities that had not surrendered - Plataea and Thespiae -before marching on the now evacuated city of Athens. The Allies (mostly Peloponnesian) prepared to defend the Isthmus of Corinth, demolishing the single road that led through it, and building a wall across it.
This strategy was flawed, however, unless the Allied fleet was able to prevent the Persian fleet from transporting troops across the Saronic Gulf. In a council-of-war called once the evacuation of Athens was complete, the Corinthian naval commander Adeimantus argued that the fleet should assemble off the coast of the Isthmus in order to achieve such a blockade. However, Themistocles argued in favour of an offensive strategy, aimed at decisively destroying the Persians' naval superiority. He drew on the lessons of Artemisium, pointing out that "battle in close conditions works to our advantage". He eventually won through, and the Allied navy remained off the coast of Salamis.
Main battle
The details of the rest of the battle are generally sketchy, and no one involved would have had a view of the entire battlefield. Triremes were generally armed with a large ram at the front, with which it was possible to sink an enemy ship, or at least disable it by shearing off the banks of oars on one side. If the initial ramming was not successful, marines boarded the enemy ship and something similar to a land battle ensued. Both sides had marines on their ships for this eventuality; the Greeks with fully armed hoplites; the Persians probably with more lightly armed infantry.
Across the battlefield, as the first line of Persian ships was pushed back by the Greeks, they became fouled in the advancing second and third lines of their own ships. On the Greek left, the Persian admiral Ariabignes (a brother of Xerxes) was killed early in the battle; left disorganised and leaderless, the Phoenician squadrons appear to have been pushed back against the coast, many vessels running aground. In the centre, a wedge of Greek ships pushed through the Persians' lines, splitting the fleet in two.