When Did Rome Lose Its Invincibility?

On August 9, 378 CE, the Roman Empire faced not just a battle but a foreshadowing of its own demise. Emperor Valens, leading his legions into the fields near Adrianople (modern-day Edirne, Turkey), believed he was facing a simple barbarian rebellion. Instead, he encountered something much larger—an irreversible shift in the power structure of the ancient world.

The enemy was the Goths, a Germanic people who had been pushed southward by the Huns. Just a few decades earlier, these so-called "barbarians" were not considered a major threat. They were refugees, seeking Roman protection. The empire, overstretched and overconfident, let them in. But Rome underestimated them, treating them as second-class subjects, starving them, and abusing them.

That arrogance culminated in the fields of Adrianople. Valens, without waiting for reinforcements, rushed into battle against the Gothic forces led by Fritigern. He assumed he was dealing with an undisciplined horde. Instead, the Goths executed a masterful cavalry ambush that shattered the Roman legions. The emperor himself was killed—his body never found.

What mattered more than the immediate defeat was the precedent it set. The Roman military machine, once invincible, had been crushed by an "inferior" force. Adrianople marked the beginning of a slow, humiliating realization: Rome was no longer the unquestioned master of Europe. The idea of an empire that could keep the "barbarians" at bay was dead.

For nearly 800 years, Rome had stood untouchable. It had seen wars, crises, and revolts, but never had an enemy breached its gates. Until 410 CE.

Alaric, the leader of the Visigoths, did not see himself as Rome’s destroyer. He saw himself as its rightful partner. He had fought for the empire, served under its generals, and played the Roman game of politics. But despite his service, he was never accepted as an equal.

His people—the Visigoths—had long been treated as outsiders, even after their victory at Adrianople. They wanted land, security, and recognition within the Roman system. The empire, fractured by internal power struggles, refused. After years of failed negotiations and betrayals, Alaric ran out of patience. If Rome would not share power, he would take it.

And so, in August 410, his forces marched on the Eternal City. The gates were opened—some say by slaves, others by starving citizens—and the Visigoths entered without resistance. What followed was three days of looting. Yet, this was no senseless destruction. Alaric’s sack was surprisingly restrained: churches were mostly spared, and he even allowed many Romans to leave unharmed. Unlike later invaders, he did not seek to destroy Rome, only to force it to acknowledge a new reality.

The sack of Rome did not end the empire—it limped on in the West for another 66 years. But it shattered the illusion of Roman supremacy. For centuries, Romans had believed their empire was eternal, divinely sanctioned, and immune to collapse. Now, the city that had ruled the known world lay at the feet of a "barbarian" king.

What Adrianople started, Alaric completed. The empire had lost its invincibility. The fall of Rome was not a sudden event but a long process, one that began with an arrogance that refused to adapt. The walls of the city still stood, but the myth of Rome’s dominance had crumbled.

And in that moment, the medieval world was born.

Sources:

• Rome's Gothic Wars: From the Third Century to Alaric by Michael Kulikowski, 2007.
• Alaric the Goth: An Outsider's History of the Fall of Rome" by Douglas Boin, 2020.
• The Day of the Barbarians: The Battle That Led to the Fall of the Roman Empire" by Alessandro Barbero, 2007.
• The Fall of the Roman Empire: A New History of Rome and the Barbarians" by Peter Heather, 2006.
• Barbarian Migrations and the Roman West, 376–568" by Guy Halsall, 2007.