In 480 BCE, Xerxes I launched a major invasion of mainland Greece. The campaign was intended to extend Persian authority into the Aegean and punish the Greek states that had resisted the empire during the reign of his father, Darius I.
Origins of the Conflict
Persia already controlled the Greek cities of western Anatolia. Between 499 and 494 BCE, several of these cities rebelled against Achaemenid rule during the Ionian Revolt. Athens and Eretria provided limited assistance to the rebels.
Darius responded by sending forces across the Aegean. Eretria was captured in 490 BCE, but the Persian army was defeated by the Athenians at Marathon. Darius began preparing another expedition but died before it could take place.
Xerxes Prepares the Invasion
After becoming king in 486 BCE, Xerxes secured his authority and continued preparations for a new Greek campaign. Soldiers, ships, supplies and labourers were gathered from numerous regions of the empire.
Ancient Greek writers described an army of extraordinary size, sometimes numbering in the millions. Modern historians consider these figures exaggerated, although the expedition was undoubtedly one of the largest military operations attempted in the ancient world.
Persian engineers constructed pontoon bridges across the Hellespont, allowing the army to march from Asia into Europe. A canal was also cut across the Athos peninsula to protect the fleet from the dangerous waters where an earlier Persian expedition had suffered heavy losses.
The Advance into Greece
Xerxes’s forces travelled through Thrace and Macedonia before entering central Greece. Many communities submitted to the Persian king, while a coalition led by Athens and Sparta prepared to resist.
Greek forces attempted to block the Persian advance at the narrow pass of Thermopylae. King Leonidas of Sparta and his remaining troops were killed after the Persians discovered a route around the Greek position.
At approximately the same time, Persian and Greek fleets fought near Artemisium. The engagement was indecisive, but the fall of Thermopylae forced the Greek fleet to withdraw southward.
The Capture of Athens
Following the Persian victory at Thermopylae, much of central Greece became vulnerable. The Athenians evacuated most of their population to nearby islands and the Peloponnese.
Persian forces entered Athens and burned buildings on the Acropolis. This destruction was presented as retaliation for the burning of Sardis during the Ionian Revolt.
The Battle of Salamis
The Greek fleet took position in the narrow waters near the island of Salamis. The Athenian commander Themistocles encouraged the Persians to enter the confined straits, where their numerical advantage became less useful.
During the battle, the Greek ships defeated a substantial part of the Persian fleet. Xerxes observed the fighting from the mainland but was unable to prevent the disorder among his naval forces.
The defeat threatened Persian supply lines and made continued operations increasingly dangerous. Xerxes returned to Asia with part of the army, leaving Mardonius to continue the campaign in Greece.
Plataea and Mycale
In 479 BCE, Mardonius renewed Persian operations and briefly occupied Athens again. A large Greek coalition confronted his army near Plataea, where Mardonius was killed and the Persian forces were defeated.
Greek forces also won a victory at Mycale on the Anatolian coast. These defeats ended the immediate Persian attempt to conquer mainland Greece and encouraged further revolts among Greek communities under Achaemenid control.
The Meaning of the Campaign
Xerxes’s invasion failed to bring all of mainland Greece into the empire, but it did not cause the collapse of Achaemenid power. Persia remained wealthy and influential, continuing to control extensive territories and intervene in Greek politics for more than a century.
Most surviving narratives of the invasion were written from Greek perspectives. They often celebrated Greek unity and freedom while presenting Xerxes as an arrogant or defeated ruler. A fuller interpretation places the campaign within the wider history of Achaemenid strategy, imperial expansion and control of the eastern Mediterranean.