The Battle of Salamis (Ancient Greek: Ναυμαχία τῆς Σαλαμῖνος, Naumachia tēs Salaminos) was fought between an Alliance of Greek city-states and the Persian Empire in September 480 BCE, in the straits between the mainland and Salamis, an island in the Saronic Gulf near Athens. It marked the high-point of the second Persian invasion of Greece which had begun in 480 BCE.

To block the Persian advance, a small force of Greeks blocked the pass of Thermopylae, while an Athenian-dominated Allied navy engaged the Persian fleet in the nearby straits of Artemisium. In the resulting Battle of Thermopylae, the rearguard of the Greek force was annihilated, whilst in the Battle of Artemisium the Greeks had heavy losses and retreated after the loss at Thermopylae. This allowed the Persians to conquer Boeotia and Attica. The Allies prepared to defend the Isthmus of Corinth whilst the fleet was withdrawn to nearby Salamis Island.

Although heavily outnumbered, the Greek Allies were persuaded by the Athenian general Themistocles to bring the Persian fleet to battle again, in the hope that a victory would prevent naval operations against the Peloponessus. The Persian king Xerxes was also anxious for a decisive battle. As a result of subterfuge on the part of Themistocles, the Persian navy sailed into the Straits of Salamis and tried to block both entrances. In the cramped conditions of the Straits the great Persian numbers were an active hindrance, as ships struggled to maneuver and became disorganised. Seizing the opportunity, the Greek fleet formed in line and scored a decisive victory, sinking or capturing at least 300 Persian ships.