Antoninianus - Postumus Colonia Agrippina, Cologne

Postumus founded the breakaway Gallic Empire in 260 after executing the legitimate emperor Saloninus at Cologne, and he governed it with surprising administrative competence for nearly a decade — maintaining Rhine defenses, issuing regular coinage, and holding annual consulships to project Roman legitimacy. His antoniniani from Cologne are generally better struck than contemporary central empire output, reflecting a functioning mint infrastructure rather than an emergency operation.

He was killed in 269 by his own troops, reportedly for refusing to allow the sack of Mainz after suppressing a rival's revolt.