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.
History of France
The Gauls became better integrated with the Empire with the passage of time. For instance, generals Marcus Antonius Primus and Gnaeus Julius Agricola were both born in Gaul, as were emperors Claudius and Caracalla. Emperor Antoninus Pius also came from a Gaulish family. In the decade following Valerian's capture by the Persians in 260, Postumus established a short-lived Gallic Empire, which included the Iberian Peninsula and Britannia, in addition to Gaul itself. Germanic tribes, the Franks and the Alamanni, entered Gaul at this time. The Gallic Empire ended with Emperor Aurelian's victory at Châlons in 274.