The Battle of the Teutoburg Forest was a military battle that took place in the year 9 AD. In the battle, an alliance of Germanic tribes won a major victory over three Roman legions. The Germanic tribes were led by Arminius; the Roman legions by Publius Quinctilius Varus.

This was more than a victory, it was the complete destruction of three Roman legions and all their commanders; the few men who survived were made slaves. It was one of the two greatest disasters in Roman military history (the other being at the Battle of Cannae). Apart from occasional raids and campaigns, the Romans never again held the Germanic land across the Rhine.

The battle began a seven-year war which ended with the Rhine as the boundary of the Roman Empire for the next four hundred years, until the decline of the Western Roman Empire.