Explanation: During the Third Servile War, a slave uprising led by gladiators, the Roman Republic endured several defeats at the hands of the rebel army which ravaged large stretches of Italy. Rome, despite being immensely warlike, was not expecting to fight a war on Italian soil, and so was unprepared for the uprising. Despite the initial success, the meandering of the rebel army, led primarily by a gladiator veteran called "Spartacus", stalled it for long enough for Rome to re-organize itself and defeat the rebels. After they were defeated, the rebel army refused to give Spartacus up - either out of loyalty, or because he had already died in the battle. Rome, terrified by the first major war on Italian soil in over a hundred years, crucified all of them along the Appian Way, a major road.
By popular imagining, the refusal of the rebels to give up Spartacus is, by the excellent but not particularly accurate 1960 film Spartacus, performed by them all claiming to be Spartacus to the Romans, rendering any attempt to find the 'real' Spartacus impossible. This is not supported by any historical accounts of the war, but is cool as fuck.