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.
Tetricus I
Gaius Pius Esuvius Tetricus was the emperor of the Gallic Empire from 271 to 274. He was originally the "praeses" (governor) of Gallia Aquitania, and became emperor after the murder of Emperor Victorinus in 271, after receiving the support of Victorinus's mother Victoria. During his reign, he faced external pressure from Germanic raiders, who pillaged the eastern and northern parts of his empire, and the Roman Empire, from which the Gallic Empire had seceded. He also faced increasing internal pressure, which led him to declare his son, Tetricus II, "caesar" in 273 and possibly co-emperor in 274, although this is debated. The Roman emperor Aurelian invaded in 273 or 274, which culminated in the Battle of Châlons, at which Tetricus surrendered. Whether this was the result of a secret agreement between Tetricus and Aurelian or necessary after his defeat is debated. Aurelian spared Tetricus, and even made him a senator and "corrector" (governor) of Lucania et Bruttii. He died of natural causes a few years after 274.