Celtic warfare
The "Gallic Wars" were a series of military campaigns waged by the Roman proconsul Julius Caesar against Gallic tribes, lasting from 58 BC to 51 BC. The Romans would also raid Britannia and Germania, but these expeditions never developed into full-scale invasions. The Gallic Wars 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. The wars paved the way for Caesar to become the sole ruler of the Roman Republic.
Gallic Empire
Marius was instated as Emperor upon Postumus' death, but died very shortly after; ancient sources writing much later state that he reigned only two days, though it is more likely, as displayed through the numismatic record, that he reigned for a few months. Subsequently, Victorinus came to power, being recognized as Emperor in northern Gaul and Britannia, but not in Hispania. Victorinus spent most of his reign dealing with insurgencies and attempting to recover the Gaulish territories taken by Claudius Gothicus. He was assassinated in 271, but his mother Victoria took control of his troops and used her power to influence the selection of his successor. With Victoria's support, Tetricus was made Emperor, and was recognized in Britannia and the parts of Gaul still controlled by the Empire. Tetricus fought off Germanic barbarians who had begun ravaging Gaul after the death of Victorinus, and was able to re-take Gallia Aquitania and western Gallia Narbonensis while the Roman Emperor, Aurelian, was engaging Queen Zenobia's Palmyrene Empire in the east. He established the imperial court at Trier, and in 273 he elevated his son, also named Tetricus, to the rank of Caesar. The following year the younger Tetricus was made co-consul, but the Empire grew weak from internal strife, including a mutiny led by the usurper Faustinus. By that time Aurelian had defeated the Palmyrene Empire and had made plans to reconquer the west. He moved into Gaul and defeated Tetricus at the Battle of Châlons in 274; according to some sources, Tetricus offered to surrender in exchange for clemency for him and his son before the battle. This detail may be later propaganda, but either way, Aurelian was victorious, and the Gallic Empire was effectively ended. In contrast with his propaganda after the recent defeat of Zenobia, Aurelian did not present his recapture of Gaul as a victory over a foreign enemy, and indeed many officials who had served in the army and administration of the Gallic Empire continued their careers—including Tetricus, who was appointed to an administrative post in Italy.