At the Battle of Teutoburg Forest in 9 CE, a rag-tag barbarian force annihilated three Roman legions, leaving the Roman emperorAugustus (27 BCE to 14 CE) to nightly wander his palace, shouting for the defeated commander, Publius Quinctilius Varus, to give him back his legions. The defeat not only stopped the growth of the Roman Empire but also created the Latin-Germanic divide that persists in Western Europe to this day.
