What was the Roman Empire's greatest defeat? It might be Teutoburg Forest in AD 9

Years earlier, as the first century BC approached its end, Augustus had decided that Germania needed to be brought under Roman control. He may well have hoped to create a buffer by extending Roman rule from the Rhine to the Elbe.

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A series of campaigns, first under Drusus and then his brother, the future Emperor Tiberius, saw the defeat of the Germanic tribes east of the Rhine and the extension of Roman influence across much of Germania Magna, as the Romans called the region. The next step would be to ‘Romanise’ these lands, and Augustus had just the man for the job: Quintilius Varus, the husband of his great-niece.

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Varus had been governor of Africa and then Syria, where he had earned a reputation as a successful administrator and able diplomat, and he had done a good job keeping a number of client rulers in line. In AD 7, he was made governor of the new German province and given command of the XVII, XVIII and XIX infantry legions, together with cavalry and auxiliary units, to control it.

On the face of it, the portents were good. There was a thriving cross-border trade, with German tribes supplying food, iron, cattle and slaves in exchange for Roman gold, silver and luxury goods. Some of the tribes had already pledged allegiance to Rome, large numbers of Germanic warriors had joined the Roman army as auxiliaries, and many young German aristocrats were serving with the Romans in order to gain military experience.

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Who was Arminius and who were the Cherusci?

One such man was a 25-year-old prince of the Cherusci, a Germanic tribe from the valley of the Weser, near the modern city of Minden. We don’t know his tribal name, but he was known to the Romans as Arminius.

He seemed to be a model auxiliary. As a child he had been sent as a hostage to Rome to assure the tribe’s good behaviour following its defeat at the hands of Drusus in 8 BC, and during that time he would have been given the same education as any young Roman aristocrat. When he came of age, he was made an eques (knight) and given a commission as an officer of auxiliary cavalry. Yet all was not as it seemed.

Beneath the Germans’ apparent acquiescence lurked a simmering resentment towards the Romans – a resentment that Arminius felt as bitterly as anyone. From the moment that Varus arrived, Arminius began to plan an uprising against Roman rule.

He knew full well that in a pitched encounter his lightly armed warriors would be no match for Varus’s armoured legions. He had to find somewhere with terrain that both suited his style of fighting and would prevent the Romans from forming the solid line of battle that had brought them victory so many times before.

The plan he came up with was simple and brilliant. He would report a rebellion in territory that the Romans were unfamiliar with, persuade them that they could and should deal with it, and then lead them into a carefully prepared trap.

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In AD 9, as Varus and his 15,000 men prepared to march westwards from their summer quarters on the River Weser towards their permanent bases near the Rhine for the winter, Arminius made his move. He arranged for some of his allies, probably warriors from the Bructeri or Angrivarii tribes, to attack Roman bases and work parties located in Cheruscan territory. Then, when news of the raids reached Varus, Arminius advised the Roman leader that it would be easy enough to make a short detour to chastise the rebellious tribes before continuing the march to the Rhine.

Another German chieftain, Segestes, repeatedly warned Varus not to trust Arminius, but Varus took no notice – and so the Roman legions took the detour that would soon lead to their destruction. Arminius was sent ahead with his auxiliary cavalry; Varus thought he was going to rally some of his tribesmen to help put down the rebellion.

Why did the Romans lose at Teutoburg?

As Varus’s main force followed along the paths that snaked through forests, fields and marshes, the long line of legionaries, auxiliaries, camp followers and baggage carts became dangerously strung out. To make things worse, the weather was appalling.

Writing in the third century, the historian Cassius Dio described the plight of Varus’s men. They were, he said, “having a hard time of it felling trees, building roads, and bridging places that required it ... meanwhile, a violent rain and wind came up that separated them still further, while the ground, that had become slippery around the roots and logs, made walking very treacherous for them, and the tops of the trees kept breaking off and falling down, causing much confusion.”

It was now that the tribesmen launched the first in a series of hit-and-run attacks, dashing in to attack stragglers or weak spots in the column, only to fall back to the safety of the forest as soon as the Romans showed any sign of effective resistance.

The pass was some four miles long but less than 200 yards wide – it was the perfect spot for an ambush, and Arminius knew it

Slowly but surely, the waterlogged Roman army was being worn down. The nearest Roman base lay at Haltern, some 60 miles to the southwest, so Varus pressed on towards it. On the third day, he and his exhausted legions reached the Kalkrieser-Niewedder Senke, a narrow corridor bounded by a steep hill to the south and an impenetrable marsh to the north. The pass was some four miles long but less than 200 yards wide – it was the perfect spot for an ambush, and Arminius knew it.

There is archaeological evidence here that the Germans built a series of low turf walls and sand ramparts along the bottom of the hill. Not only did these keep the Germans hidden, they also narrowed the path, denying the Romans the space they needed to form up properly into a line of battle. As the battered Roman column filed into the pass, it found itself trapped in a deadly bottleneck from which there was no escape. Archaeological finds also suggest that some of the Romans tried to storm the ramparts, but to no avail.

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Realising that there was no way out, and knowing that if he fell into the hands of the Germans his end would be a long and messy one, Varus chose to commit suicide, falling on his sword in the traditional Roman manner. Attacked from all sides by the triumphant Germanic warriors, the remaining soldiers of Varus’s legions were massacred.

Only a handful managed to escape and make their way to safety, and when they did the story they told was shocking. As Velleius Paterculus, a retired officer who was a contemporary of Varus later put it: “An army unexcelled in bravery, the first of Roman armies in discipline, in energy, and in experience in the field, through the negligence of its general, the perfidy of the enemy, and the unkindness of fortune … was exterminated almost to a man by the very enemy whom it has always slaughtered like cattle.”

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The Roman army’s reputation for invincibility had been completely destroyed. As news of the disaster spread, Roman bases in Germany were either hastily abandoned or overrun. Emperor Augustus, fearing that Arminius might march on Rome itself, expelled all Germans and Gauls from the city.

But Arminius’s eyes were firmly fixed on Germany. He took Varus’s severed head and had it sent to Maroboduus, another powerful Germanic leader, with the offer of an anti-Roman alliance. Maroboduus declined, sending the head to Rome for burial, and remained neutral throughout the fighting that followed.

Roman retaliation was inevitable. Imperial forces on the Rhine were boosted from five legions to eight, and Tiberius and later Germanicus were ordered to avenge the defeat and punish Arminius. This was easier said than done, for the Cheruscan chief proved a wily foe.

In AD 15, Roman forces under Germanicus finally returned to the Teutoburg battlefield, and what they found there horrified them

In AD 15, Roman forces under Germanicus finally returned to the Teutoburg battlefield, and what they found there horrified them. Human heads were nailed to trees, there was grim evidence of human sacrifice and the bones of dead men and animals lay everywhere.

After pausing to oversee the burial of his dead comrades, Germanicus resumed the pursuit. He enjoyed some successes, recapturing two of the precious eagle standards that had been lost at Teutoburg, but came close to defeat himself when his four legions were ambushed by Arminius – only divisions amongst the Cheruscan commanders spared him from disaster, and the Romans managed to escape the trap that had been set for them and rout the Germans.

The following year Germanicus once again defeated Arminius, this time at Idistaviso, somewhere near Minden, but the Roman appetite for warfare across the Rhine was waning. Despite his protests, Germanicus was recalled to Rome in AD 16.

What happened to Arminius?

In AD 17, Arminius was at war again, this time against his old rival King Maroboduus. Arminius was victorious and Maroboduus was forced to appeal to Tiberius, now Emperor of Rome, for sanctuary. Arminius was now at the height of his powers – but for many he was now just too powerful. In AD 21, he was murdered by a member of his own family.

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The Roman historian Tacitus wrote of him: “Make no mistake. Arminius was the liberator of Germany, one who defied Rome, not in her early rise, as other kings and generals, but in the height of her empire’s glory. The battles he fought were indeed indecisive, yet he remained unconquered in war. He lived for 37 years, 12 of them in power, and he is still the subject of song among barbarous nations.”

Arminius was never the unifying figure that later German nationalists made him out to be, and his victory at Teutoburg didn’t prevent the Romans from returning in force shortly afterwards. But his resistance was a major factor in leading Rome to abandon its ambitions of making the collection of independent tribal kingdoms we now call Germany part of its empire.

Roman troops would indeed cross the Rhine in the future, but these would be punitive campaigns, not wars of conquest. The river would remain a boundary between Germanic and Latin cultures.

Where is the Teutoburg Forest battlefield?

As time went on, the site of the fighting was gradually forgotten. The actual location, at Kalkriese, Osnabrück, was discovered in 1987 by British soldier and metal detectorist Tony Clunn, who initially found a number of coins and, significantly, three lead slingshots. Professional archaeologists investigated and confirmed that this was indeed the scene of the battle.

Since the early 1990s, more than 5,000 battle-related objects have been found along a corridor some 15 miles long and one mile wide – evidence of the mobile nature of the fighting. These have included human bones, spearheads, pieces of armour, nails, and bells that once hung from the necks of Roman mules. There is also evidence of the long turf wall that played such an important part in the Roman defeat.

Julian Humphrys is a historian and author specialising in battlefields. His books include Enemies at the Gate (English Heritage, 2007)

This content first appeared in the March 2018 edition of BBC History Revealed