Arminius defeated three Roman legions at the Battle of the Teutoburg Forest in 9 CE.
Arminius was a Germanic chief of the Cherusci who had received Roman military training and served as an auxiliary commander. He used his knowledge of Roman tactics and the terrain to organize an alliance of Germanic tribes against the Roman governor Publius Quinctilius Varus.
The ambush took place in difficult, wooded territory while Varus was marching from summer camps toward winter quarters. Legions XVII, XVIII, and XIX were destroyed, along with their auxiliary troops and camp followers. The defeat ended Rome’s attempt to turn the lands east of the Rhine into a permanent province.
The battle is often called the Varus disaster, or clades Variana, in Roman sources. Arminius later fought Rome again, but his victory did not create a unified Germanic kingdom. The Roman Empire retained its provinces west of the Rhine and continued campaigns beyond the river.