It took little more than a single generation for the centuries-old Roman Empire to fall. In those critical decades, while Christians and pagans, legions and barbarians, generals and politicians squabbled over dwindling scraps of power, two men – former comrades on the battlefield – rose to prominence on opposite sides of the great game of empire. Flavius Stilicho, the half-barbarian general behind the Roman throne, dedicated himself to restoring imperial glory, only to find himself struggling for his life against political foes. Alaric, King of the Goths, desired to be a friend of Rome, was betrayed by it, and given no choice but to become its enemy. Battling each other to a standstill, these two warriors ultimately overcame their differences in order to save the empire from enemies on all sides. And when one of them fell, the other took such vengeance as had never been seen in history.

In AD 376 the Goths, a barbarian tribe who had migrated from Scandinavia down into Eastern Europe, were under pressure from the Huns, voracious horse-borne raiders of the eastern steppes. The Goths wished to become assimilated – subjects of the empire – in exchange for imperial protection.

In the past this longstanding policy had greatly benefitted both the empire and barbarians, for whom citizenship and assimilation, by force if necessary, meant losing their own culture, obeying Roman law and adopting Roman ways – becoming Roman. “This, more than anything else, is why Rome flourished,” declared the 1st Century historian Plutarch, “she always united and assimilated within herself those whom she conquered.”

Alaric enters Athens

The Goths, however, were not assimilated. Corrupt authorities mistreated and abused them to the point that they went on a rampage. At Adrianople in 378, Eastern Emperor Flavius Valens arrived with an imperial army to stop them. His legions were destroyed, Valens was killed, and the Goths came into the empire unconquered, on their own terms. For them it amounted to a successful invasion. Valens’ successor, Emperor Flavius Theodosius, was forced to deal with them as equals. To replenish his legions, he hired Goth warriors as mercenaries. Alaric, then a young bandit chieftain, was brought to heel by Stilicho. Theodosius made them both commanders in his army.

At the Battle of the Frigidus River in 394, Christian Theodosius marched against the pagan Western Roman emperor Eugenius. The battle was a bloody two-day affair, in which Theodosius ordered his Goth mercenaries against prepared enemy positions. Half – 10,000 men – were killed. The battle was won, but even contemporary writers suspected the emperor wished to bleed his ranks of potential enemies.

After his death Stilicho, as guardian of Theodosius’ young son Honorius, became de facto Western emperor. With the Western army now under his command, he no longer needed Goth mercenaries. He dismissed Alaric and his men from service. Seeking a home of their own, they ran amok over Greece until both the Eastern and Western empires were forced to come to terms with them. By now Alaric trusted neither, and played them off against each other. The Goths became the deciding factor in the balance of power.

In those days any commander with an army behind him could declare himself emperor, and many tried. Fighting each other over many years, Stilicho and Alaric forged mutual respect, finally deciding to combine forces and re-unite the Eastern and Western empires by force, together. This cooperation with barbarians was seen by Stilicho’s political enemies as treason. They talked fickle Honorius into declaring his greatest general a traitor, and ordering his execution.

Stilicho’s death left Alaric as Italy’s best military leader. He was eager to command Rome’s army for Honorius, in return asking only for a homeland for his people. With a typical Roman’s dislike of barbarians, the emperor refused to come to terms. Both used Rome as a bargaining chip in their negotiations. Alaric had no great wish to take the city, but in the end was left with little choice. The Goths blockaded Rome until the starving citizens simply opened the gates.

Rome’s failure to either conquer or assimilate the Goths – to make them Roman, even though that had once been their most ardent wish – left the Empire with what amounted to a hostile nation within its own borders. Rome was not conquered by outsiders. The Goths wished to be Roman. Instead they made Rome theirs.

Don Hollway is the author of At the Gates of Rome: The Fall of the Eternal City, AD 410, now available from Osprey Publishing.