In 279 BC, a huge army of Celtic warriors descended on the ancient kingdom of Macedon and wreaked havoc. The Macedonian king, Ptolemy Ceraunus, was brutally slain on the battlefield. Just decades earlier, Macedon had been an epicentre of Alexander the Great’s all-powerful empire. Now it lay at the mercy of tens of thousands of ‘barbarians’. It was the beginning of a massive, Celtic invasion of the Greek mainland.
Having defeated Ptolemy Ceraunus in battle, the Celtic horde threatened to wreck havoc. City gates were closed and desperate prayers were made by the Macedonians. Having heard of the fate of their countrymen that had served alongside Ceraunus, they knew a fate worse than death awaited them if the barbarian horde was not stopped. Hopelessness spread – the golden age of their nation’s power seemed a distant memory. Yet amid this turmoil one man acted. His name was Sosthenes.
A Macedonian aristocrat, Sosthenes realised that prayers alone would not stop the barbarian menace and stepped forward as the leader the moment needed. Rallying as many Macedonians as were physically able to carry a sarissa, sword, javelin or bow, Sosthenes gathered a small army and marched to confront the Celtic leader Bolgius. The result was remarkable, as Sosthenes and his army,
…repulsed the Gauls in the midst of their exultation at their victory and saved Macedonia from devastation.
But had he? Sosthenes had successfully taken Bolgius and his Celtic horde by complete surprise. His foe retreated in all haste, forced to leave their plunder behind and the little-remembered Sosthenes became the new saviour of Macedonia. Yet this would prove just the beginning.
Sosthenes soon learned that another Celtic horde had invaded the country. His name was Brennus, a Celtic warlord hailing from the otherwise-unheard of Prausi tribe. When Bolgius led his force into Macedonia, Brennus had been campaigning further north in Paeonia, leaving a trail of death and destruction in his wake. Backed by his own great army – over 150,000 men strong – Brennus ventured into Macedonia intent on revenge. They made their presence known to the Macedonians, ravaging the countryside and chiding their opponents.
All Macedonian eyes turned to their saviour Sosthenes. Would he be able to repeat the miraculous victory against Bolgius? Sosthenes lead his small, determined Macedonian force into battle against the Celtic horde. But the battle was a lost cause: Brennus’ horde was simply too great. Sosthenes ordered the retreat, pulling his remaining force within the walled cities of the country. There they would weather the Celtic storm.
Macedonia in turmoil
Sosthenes could only watch on as Brennus ravaged Macedonia. The Macedonians dispatched messengers to their Hellenic neighbours – to Pyrrhus in the West, Ptolemy Epigonus in Illyria and their former-adversary Antigonus in the south. They sought a saviour. As the Macedonians awaited a response, the Celtic leader sought a higher prize than the countryside. To placate his own soldiers, Brennus sought a prize that guaranteed riches. He did not have to look far.
To the south of Macedonia lay the famed cities of antiquity, the heartlands of Hellenic culture. Beaming as the epicentre of Hellenic culture was Delphi, home of the Pythia and the most prestigious sanctuary in the Greek world. Adorned with splendorous dedications – varying from intricate bronze statues to majestic treasures – the riches of Delphi were common knowledge throughout the Greek world. Brennus claimed: “The gods being rich, ought to be liberal to men.”
Persuaded by his promises of unmatched wealth and eternal fame, Brennus’ commanders eagerly agreed to his proposal and gathered their warriors for the long march south. United, the size of this horde was phenomenal. Most soldiers fought on foot, lightly-armoured and relying more on their individual skill as fighters than the discipline of formation. In his army Brennus also had a sizeable amount of cavalry, trained in one of the most fascinating tactics of the age.
The ‘Trimarchisia’ system
Prepared for all the unexpected eventualities of battle, two servants accompanied each of Brennus’ horsemen on the field. These grooms were much more than your average stable-hands. Well trained in the art of war, Pausanias recalls the unique role they played in battle:
When the Gaulish cavalry were in battle, the grooms would stay behind the ranks and make themselves useful with new mounts when a horse or rider fell, but when a man was killed the groom would mount the horse in place of his master.
Employing such a tactic, Brennus’ enemies would have faced a seemingly-endless tide of Celtic cavalry.
Backed by his formidable army, Brennus now lead his force south, leaving a plundered Macedonia in his wake. Little did he know, however, that a large and united Greek army was quickly being mobilised. The Greeks had heard vivid reports of the great terrors these barbarians had inflicted on their northern neighbours. They were determined the heartlands of Hellenism would not suffer a similar fate. After all, these cities had overcome similar odds in the past.