Quintillus was still in command of the army in Northern Italy, while his brother Claudius II died of plague in January 270. He was quickly confirmed as the new emperor by a mournful Senate and country. In fact he was prefferred over Aurelian by army and senate since the latter was understood to be a strict disciplinarian.
Quintillus' first act of state was a request for deiification which was immediatley granted by a sincerely mourning senatorial assembly. But in a fatal error, Quintillus remained for some time at Aquileia, not moving immediately to the capital to consolidate his power.
Before he had chance to make any further mark on the empire, the Goths caused trouble again in the Balkans. Aurelian, commander on the Lower Danube, destroyed them decisively and was now hailed emperor by his armies. Aurelian, if truthfully or not is unknown, now claimed that Claudius II had meant him to be the next emperor. Though Quintillus countered that he was the true appointed successor, since he had two sons.
Quintillus' desperate attempt to resist lasted only a few days. In no time he was abandoned by all and committed suicide in true looser's fashion by slitting his wrists (September AD 270). The exact length of his reign is estimated at 70 - 100 days.