The Battle of the Teutoburg Forest (a.k.a. the Varian Disaster)
In AD 9, the Germanic ambush of 3 Roman legions marching in the Teutoburg Forest (a.k.a. the Varian Disaster) took place in the Teutoburg Forest in northwestern Germania. This region of Germania was outside of the boundaries of the Roman Empire, however it was the homeland of the Nordic and Germanic raiders who frequently raided Roman Gaul (modern day France).
An alliance of Germanic tribes, led by the Germanic “barbarian” Arminius (who had acquired Roman citizenship and received a Roman military education, allowing him to personally deceive the Roman commander and foresee the Roman army’s tactical responses) ambushed and decisively destroyed three Roman legions (of somewhere between 16,000 and 36,000 men) and their auxiliaries, led by Publius Quinctilius Varus.
It is said that Augustus Caesar was so distraught by this massacre that for months afterwards he walked the halls of his palace in Rome at night crying “Varus give me my legions back!”.