Varus was sent to run Germania province in 7AD. When he arrived the German tribes seemed to be settling down to imperial rule, but their new commander tried to rush the process. He treated them as if they were slaves and demanded money from them. In short, he behaved as if they were a conquered nation. They weren't.
The Germans resented the new boss, but pretended to go along with him and obey his orders. Varus fell for it, scattered his troops, and allowed himself to be lured away from his power base on the Rhine into the territory of the Cherusci tribe.
He had become chums with one of their leaders, Arminius, who has gone down in history as "Herman the German". Varus would not hear a word against him - until the trouble began.
News came of a revolt. It had been started a long way away deliberately to entice the Roman forces to march back across what he thought was friendly territory. Herman set out with him, but soon left, telling Varus he was getting troops to help. Well, it was only half a lie.
In the middle of the Teutoburger Wald, a miserable area of marsh, forest and hills, Herman ambushed his mate. Varus's three mighty legions could not fight properly in the rough terrain, as the German who had served as a legionary knew. A storm blew up. The Roman columns straggled as the ground turned to mud. Anything that was not essential was burnt or abandoned. When the disorganised soldiers tried to charge they bumped into each other and into the trees. They couldn't draw their bows or throw their javelins to any good effect and their rain-soaked shields became useless.
Nearly 15,000 Romans were massacred in three days. When the emperor Augustus heard the news he reportedly cried out: "Quintilius Varus, give me back my legions." He could not. He had fallen on his sword. Rome never did conquer Germany and the cost of defending its borders on the Rhine stopped the march of empire elsewhere.