Okay, there we go... (my guess)
What you are probably referring to is the massacre in the Teutoburger Wald (Teutoburger forest).
What I know of it. The Romans were campaigning in order to mover the northern border from the Rhine towards the Elbe river. To this end they also dug canals etc. etc. In 9 ad (IIRC) one such campaign was led by Publius Quinctilius Varus, with three legions under his command. He ledd a campaign deep into Germany. He was (he thought) aided by a German commander, Armius (Herman), prince of the Cherusci, with his troops. In reality, Arminius wanted to crush the Romans... Arminius had struck a deal with a number of other tribes (Bruteri, Masdci and Chatti) to cooperate. When the Romans reached a position far into Germany, these tribes rose in revolt. For some unknown reason, Varus decided he had to get back to the Rhine, instead of pitching camp, and ride out the storm as best he could.
In order to do so, he had to lead his troops through difficult terrain of forests and marshes. IIRC he did not even choose the same way back as they had come. He relied on Arminius to get im back. Instead Arminius led the Romans into a prepared ambush in the woods. His troops slowly deserted and joined the rebels, untill he himself took of as well. The Romans were confronted with a system of banks and ditches that, in cooperation with the forest, was designed to make it impossible for them to form into proper formations. The strung-out troops were split into smaller groups and defeated in detail... only very few survived, Varus not being among them....Also the legionary standards were lost
Supposedly, when he heared of the news, Augustus at some points banged his head against the wall while crying: "Vare, Vare, redde mihi legionis !!" (Varus, Varus, give me my legions back). During various punitive expeditions, either later under Augustus, or under Tiberius, and one under Caligula, all of the lost standards were recovered. The destroyed legions were never reformed.
The site of the battle is not exactly known... some say it is now a field, others suggest that it is still (partly) located in a forest. Many locate the battle near the vicinity of Kalkriese, a little to the north of Osnabrück, in present day Germany.
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