Short answers, pulled from the story.
The Gallic Empire was a breakaway western portion of the Roman Empire that functioned as a separate state from 260 to 274. It was established by the Roman general Postumus in 260 and at its height included Germania, Gaul, Britannia, and Hispania. It was retaken by Emperor Aurelian at the Battle of Châlons in 274.
Postumus, the Roman governor of Germania Superior and Inferior, founded the Gallic Empire in 260. He did so after besieging Colonia Agrippina, killing Gallienus's son Saloninus and the praetorian prefect Silvanus, and establishing a parallel government with its own senate, consuls, and Praetorian Guard.
Emperor Aurelian defeated the last Gallic emperor, Tetricus I, at the Battle of Châlons in 274. Tetricus and his son Tetricus II were spared; Tetricus was given an administrative post in Italy. Aurelian did not frame the reconquest as a victory over a foreign enemy, and many Gallic Empire officials continued their careers under Rome.
The rulers were Postumus (260-269), followed by Marius (269), Victorinus (268/69-271), Tetricus I (271-274), and Tetricus II (273-274) as caesar and co-consul. Several usurpers, including Laelianus, Domitian II, and Faustinus, also briefly challenged for power.
Victoria was the mother of the emperor Victorinus. After his assassination in 271, she took control of his troops and used her influence to install Gaius Pius Esuvius Tetricus as the next emperor. Her existence, once debated, was confirmed by the discovery of her funerary stele in 2012.
The Gallic emperors are known primarily from coins they minted. The numismatic record documents their consulships and corrects errors in later ancient sources, such as the claim that Marius ruled for only two days when coins suggest a reign of several months. Not all consul names from the period have survived.