Battle of Alesia
Caesar engaged in the Gallic Wars (58–50 BC), which led to his conquest of Gaul beyond Gallia Narbonensis. When the Helvetii, a federation of tribes from what is now Switzerland, planned a migration to the Atlantic coast through Gaul, Caesar went to Geneva and forbade the Helvetii to move into Gaul. While he went to Gallia Cisalpina to collect three other legions, the Helvetii attacked the territories of the Aedui, Ambarri, and Allobroges, three Gallic tribes, which called for Caesar’s help. Caesar and his Gallic allies defeated the Helvetii. The Gallic tribes then asked for Caesar to intervene against an invasion by the Suebi, a Germanic tribe. Caesar defeated the Suebi. In 57 BC he intervened in intra-Gallic conflicts and marched on the Belgae of northern Gaul. From then on he conquered the Gallic peoples one by one. His successes in Gaul brought Caesar political prestige in Rome and great wealth through the spoils of wars and the sale of war captives as slaves.
Gallic Wars
Discontent among the subjugated Gauls prompted a major uprising in the winter of 54–53 BC, when the Eburones of north-eastern Gaul rose in arms under their leader Ambiorix. Fifteen Roman cohorts were wiped out at Atuatuca Tungrorum (modern Tongeren in Belgium) and a garrison commanded by Quintus Tullius Cicero narrowly survived after being relieved by Caesar in the nick of time. The rest of 53 BC was occupied with a punitive campaign against the Eburones and their allies, who were said to have been all but exterminated by the Romans.