Battle of Thermopylae (279 BC)

Battle of Thermopylae
Part of Gallic invasion of the Balkans
Route of the Gallic invasion of the Balkans
Date 279 BC Location Thermopylae Result Gallic victory
Belligerents
Gauls	Aetolians Boeotians Athenians Phocians
Commanders and leaders
Brennus

The Battle of Thermopylae was fought in 279 BC between invading Gallic armies and a combined army of Greek Aetolians, Boeotians, Athenians, Phocians at Thermopylae. The Gauls under Brennus were victorious, and advanced further into the Greek peninsula where they sacked Delphi.

Gallic groups, originating from the various La Tène chiefdoms, began a south-eastern movement into the Balkan peninsula from the 4th century BC. Although Gallic settlements were concentrated in the western half of the Carpathian basin, there were notable incursions, and settlements, within the Balkan peninsula itself.

From their new bases in northern Illyria and Pannonia, the Gallic invasions climaxed in the early 3rd century BC, with the invasion of Greece. The 279 BC invasion of Greece proper was preceded by a series of other military campaigns waged in the southern Balkans and against the kingdom of Macedonia, favoured by the state of confusion ensuing from the complex and divisive succession processes following Alexander's sudden death.

The Celtic military pressure toward Greece in the southern Balkans reached its turning point in 281 BC. In 280 BC a great army, comprising about 85,000 warriors, approached from Pannonia and split into three divisions. These forces marched south in a great expedition to Macedon and central Greece. Under the leadership of Cerethrius, 20,000 men moved against the Thracians and Triballi. Another division, led by Brennus and Acichorius moved against Paionians while a third division, headed by Bolgios, headed towards the Macedonians and Illyrians.

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