Gauls
In 58 BC Julius Caesar launched the Gallic Wars and had conquered the whole of Gaul by 51 BC. He noted that the Gauls (Celtae) were one of the three primary peoples in the area, along with the Aquitanians and the Belgae. Caesar's motivation for the invasion seems to have been his need for gold to pay off his debts and for a successful military expedition to boost his political career. The people of Gaul could provide him with both. So much gold was looted from Gaul that after the war the price of gold fell by as much as 20%. While they were militarily just as brave as the Romans, the internal division between the Gallic tribes guaranteed an easy victory for Caesar, and Vercingetorix's attempt to unite the Gauls against Roman invasion came too late. After the annexation of Gaul a mixed Gallo-Roman culture began to emerge.
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.