Gallic Wars
The Gallic Wars were a series of military campaigns waged by the Roman proconsul Julius Caesar against several Gallic tribes. Rome's war against the Gallic tribes lasted from 58 BC to 50 BC and culminated in the decisive Battle of Alesia in 52 BC, in which a complete Roman victory resulted in the expansion of the Roman Republic over the whole of Gaul (mainly present-day France and Belgium). While militarily just as strong as the Romans, the internal division between the Gallic tribes helped ease victory for Caesar, and Vercingetorix's attempt to unite the Gauls against Roman invasion came too late. The wars paved the way for Julius Caesar to become the sole ruler of the Roman Republic.
Gaul
As many as a million people (probably 1 in 5 of the Gauls) died, another million were enslaved, 300 clans were subjugated and 800 cities were destroyed during the Gallic Wars. The entire population of the city of Avaricum (Bourges) (40,000 in all) were slaughtered. Before Julius Caesar's campaign against the Helvetii (present-day Switzerland), the Helvetians had numbered 263,000, but afterwards only 100,000 remained, most of whom Caesar took as slaves.