The Battle of the Teutoburg
The Battle of the Teutoburg Forest in 9 AD was one of the darkest episodes in Roman military history. Inflicted upon an Empire at its pinnacle, at a time when contemporary writers were boasting of an imperium sine fine, the defeat at Teutoburg resulted in the complete and sudden annihilation of the XVII, XVIII and XIX legions, some sixteen to twenty thousand men - Rome's worst military defeat since Crassus fell at Carrhae in 53 BC.
Led by the general Publius Quinctilius Varus, whose incompetence was unfairly exaggerated in the aftermath of the battle an effort to provide a scapegoat, the Roman army had been marching in line deep though the heart of the German forest when it was ambushed on all sides by a confederation of Germanic tribes. For hours the Romans managed to keep their assailants at bay, no mean feat considering their line was stretched to between 15 and 20 kilometres and they were fighting in dense forest and heavy rain, and as darkness fell on the forest Varus' men hastily erected a fortified camp, which they held through the night.