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.
Marcus Popillius Laenas
Near the end of his consulship with Gnaeus Manlius Capitolinus Imperiosus, the Tarquinians invaded the Roman territories on the Etruscan border, if this Gallic war took place 30 years after the occupation of Rome by the Gauls (in 386/5 BC). Dio Cassius apparently identifies this war with the one in Camillus's fifth dictatorship when the election of the consuls was resumed. Those events took place in 364 BC, about a decade earlier, according to Livy.