Battle of the Teutoburg Forest

The Battle of the Teutoburg Forest, also called the Varian Disaster (Latin: Clades Variana) by Roman historians, was a major battle fought between an alliance of Germanic peoples and the Roman Empire between 8 and 11 September 9 CE, possibly near modern Kalkriese. Fighting began with an ambush by the Germanic alliance on three Roman legions being led by Publius Quinctilius Varus and their auxiliaries; the alliance was led by Arminius, a Germanic chieftain and officer of Varus's auxilia. Arminius had received Roman citizenship and a Roman military education, thus allowing him to deceive the Romans methodically and anticipate their tactical responses.

Teutoburg Forest is considered one of the most important defeats in Roman history, bringing the triumphant period of expansion under Augustus to an abrupt end. It dissuaded the Romans from pursuing the conquest of Germania, and so can be considered one of the most important events in European history.

The provinces of Germania Superior and Germania Inferior, sometimes collectively referred to as Roman Germania, were established in northeast Roman Gaul, while territories beyond the Rhine remained independent. Retaliatory campaigns were commanded by Tiberius and Germanicus and enjoyed success, but the Rhine became the border between the Roman Empire and the rest of Germania. Rome then made no major incursion into Germania until Marcus Aurelius (r. 161–180) during the Marcomannic Wars.

Some of the descendants of the vassal kingdoms, like the Suebi (by suzerainty), that Augustus tried to create in Germania to expand the romanitas and the Empire, were the ones that invaded Rome in the fourth and fifth centuries.