How a Marauding Celtic Army Rocked the Greek World to Its Core | History Hit

How a Marauding Celtic Army Rocked the Greek World to Its Core

Image Credit: Public Domain

After overwhelming a Greek army at Thermopylae in 279 BC, a large Celtic army (perhaps some 30-40,000 men) descended on central Greece, hungry for plunder. They were led by a chieftain called Brennus, who had set his sights upon Delphi, the centre of the Hellenic World.

Often overlooked compared to other seismic campaigns in ancient Greece such as the Persian Wars and the Roman conquest, this terrifying Celtic invasion was an extraordinary event. Meanwhile its details are often unclear and debated.

War on Delphi

Renowned as the home of the Pythia, the sanctuary at Delphi was the religious heart of the Hellenic World. Lycurgus, Solon, Croesus and Philip II – all were legendary figures who had once come from far and wide to seek guidance from the oracle of Apollo.

Geographically too this beautiful precinct was also highly significant, housing the famed omphalos stone – ‘the bellybutton of the world.’ Delphi was much more than just a sanctum: it was the epicentre of all things Hellenic.

Delphi, Greece.

Image Credit: Shutterstock

Delphi’s celebrity status brought the sanctuary rich rewards: its treasures were vast and well-known. Seizing the sanctuary’s treasures had always been Brennus’ goal. Yet taking this precinct would not be easy – even following his victory at Thermopylae.

Situated on the southern slope of Mount Parnassus, Delphi’s natural defences were formidable. Whether their foe attacked through the narrow gorges of the mountain to the north or ascended the steep climb from the valley to the south, any defending force could rain death and destruction down on their hapless enemies. There was no need for a wall; Mount Parnassus provided Delphi ample protection. Whether it could withstand the approaching Celtic storm would soon be put to the test.

The Thermopylae aftermath

The frightened Delphians sought advice from the Pythia, the high priestess also known as the Oracle. She allegedly provided them with a short, but soothing reply:

I will defend my own.

Pausanias 10.23.1

The Oracle had spoken; they would put their trust in Apollo and protect the sanctuary from the approaching horde. Reassured, the Delphians prepared their desperate defence, sending out a call for aid and gathering as many projectiles as they could find. Javelins, arrows and large boulders from the mountainside – the defenders collected all to rain down from the precipices of Mount Parnassus. Battle was imminent.

The Battle of Delphi: 279 BC

Brennus was sure to keep the Celtic momentum surging forwards and his men soon arrived near the sanctuary. To the defenders, the barbarian horde must have looked terrifying. Thanks to the Pan-Hellenic army’s defeat at Thermopylae and the speed of Brennus’ march, the defenders had only a minuscule force in comparison – mostly Phocians from across the region. The odds were heavily stacked against them.

Fresh from pillaging the surrounding land, Brennus and his army headed into the gorges of Mount Parnassus towards Delphi. Positioning themselves on the precipices above, the defenders gathered their projectiles and unleashed a storm of death down on the approaching Celts.

The result was devastating. Hemmed in on either side – no more than two or three men abreast at places – Brennus and his men struggled to avoid the javelins, arrows and huge rocks being hurled down from overhead. Still the Celts persisted.

Speculative illustration of ancient Delphi by French architect Albert Tournaire

Image Credit: Public Domain

Finally, with many already fallen, the power of the Celtic force proved too much. The Celts occupied the sanctuary; the defence was shattered. Remaining defenders presumably retreated higher up the slopes of Mount Parnassus. Delphi, the cultural heart of the Hellenic World, had fallen to the ‘barbarians’. Brennus bathed in his victory. Delphi was his, as was an abundance of riches. He could not linger there long, however. Deep within hostile territory, the fighting was far from over.

The retreat

At sunrise Brennus ordered his army, likely laden with gold, wine and various other treasures, to start the long march back north – through the narrow gorges of Parnassus towards their comrades at Thermopylae. Seeing the Celts withdrawing from the sanctuary, the remaining defenders acted. Coming down from above the precinct they attacked the Celtic rear-guard. Having the higher ground and well out of reach, they once again hailed death down on their foe.

That was not all. Using their local knowledge, some of the Phocians traversed the precipices of Mount Parnassus surrounding the pass. They managed to position themselves on either side of the road, awaiting the Celtic retreat.  The result was devastating:

When the battle opened the barbarians, particularly Brennus’ own men, who were the biggest and strongest of the Gauls, resisted with spirit, though they were shot at from every direction and suffered badly from the cold, especially the wounded.

Pausanias 10. 23. 4


Amid the chaotic retreat the Celts suffered a crushing blow. Brennus, perhaps as he was fighting in the rear-guard of the army, was wounded. Barely-conscious, his comrades hastily withdrew their leader from the front lines. The constant attacks had thrown the booty-laden Celts into total disarray. And another disaster followed that night:

The disturbance broke out among the soldiers in the deepening dusk, and at first only a few were driven out of their minds; they thought they could hear an enemy attack and the hoof-beats of the horses coming for them. It was not long before madness ran through the whole force. They snatched up arms and killed one another or were killed, without recognising their own language or one another’s faces or even the shape of their shields.

Pausanias 10. 23. 5

The result was slaughter. In their confusion, friend killed friend and ally killed ally. The Celtic army was disintegrating, victim to chaos and confusion.

No mercy

The Phocians resumed their attacks the next day. Full of confidence, they now grew bolder in their attempts to wither away their foe, attacking their foraging parties with deadly success. Slowly they tightened the noose around the throat of the Celts. Amid all this hardship, a glimmer of hope appeared. Achichorius, Brennus’ second in command and the chief in charge of Brennus’ remaining troops that had remained at Thermopylae, had arrived with more men to aid the retreat. This relief would be bitter-sweet.

Achichorius’ force had suffered heavily from devastating hit-and-run attacks – this time from the Aetolians. Just as the Phocians were keen to avenge the sacking of Delphi, the Aetolians were equally-determined to destroy the horde, zealous in their desire to exact retribution on the architects of the Callion atrocity. Their efforts paid dividends. Achichorius’ army arrived battered and bruised – hardly a relief force at all.

A heavy price

By the time the reunited Celtic force reached the border of Phocis, the price paid had been a heavy one. Over 6,000 warriors had died at Delphi – most during the perilous retreat. According to Pausanias, another 20,000 Celts would never leave the region – half having met their end during the paranoid frenzy that had seized their camp days before; the other half from starvation.

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As the retreating horde reached Boeotia, devastating news spread through the Celtic army: Brennus, the architect of the whole invasion and victor of Thermopylae, was dead. Our sources differ on how he met his end: according to Pausanias, he committed suicide by drinking diluted wine; Diodorus tells us he slew himself.

Having burned the body of their fallen general, Achichorius and the remaining Celts continued north with all haste. Various Greek forces awaited them, constantly harassing the barbarians in their desire for vengeance. The Celtic force withered.

Finally, after much horrific fighting and desperate struggles, Achichorius and what remained of the Celtic expedition passed Thermopylae and reached the large, fertile plains of Thessaly and soon after that, Macedonia. The Celtic invasion of Greece was over. Those who had survived the expedition settled soon after, forming new Celtic kingdoms in both Thrace and Moesia. Others ultimately settled in central Asia Minor (Anatolia), where they became known as the Galatians.

The Hellenic ‘cover up’?

Celebrations were sure to follow the expulsion of the Celts from the most prestigious sanctuary in the Hellenic World. Depicted as the greatest barbaric threat to Greek freedom since the Persian Wars, epic Greek tales about Hellenic heroism in the face of the invasion – called Galatika – soon became widespread.  In their desires to eradicate all memory of the Celtic sacking of their most holy site, a festival emerged to celebrate deliverance from the Celtic menace: the Soteria. Through these epic celebrations, any memory of the Celtic pillaging quickly evaporated.

Pausanias and Pompeius Trogus – our two main literary accounts for the sacking – both state that Delphi was saved from the Celts thanks to Greek heroism and divine intervention. They both claimed that the Celts failed to reach, and sack, Delphi. Yet certain later discoveries suggest otherwise.

Brennus’ horde had consisted of various Celtic tribes, one of which were the Tectosages. The Tectosages had originated from Southern Gaul, around the area of Tolosa.

The Tolosa Gold

In 106 BC, a fascinating discovery was made in Southern Gaul. Quintus Caepio, the Roman general who would become famous for his disastrous defeat at Arausio the following year, captured the city of Tolosa – home of the Tectosages tribe. What Caepio discovered in the city is fascinating to consider. Strabo recalls:

And it is further said that the Tectosages shared in the expedition to Delphi; and even the treasures that were found among them in the city of Tolosa by Caepio, were, it is said, a part of the valuables that were taken from Delphi.

Strabo IV. 1. 13

According to some accounts, this was Delphic gold, captured by Brennus’ iconic expedition and sent home by the Tectosages to the lands of their ancestors. Believing this Caepio and the army thus seized the sacred treasure, receiving orders to have it sent back to Rome. Yet the gold would never reach the eternal city. On its journey it disappeared in mysterious circumstances.

Whether the Tolosa gold was the Delphic treasure is uncertain to say the least; perhaps it was just a story. Yet regardless of the extent of the tale’s truth, one thing appears clear: the story that Brennus and his horde had plundered the sanctuary was well-known by Roman times.

Tristan Hughes