However, he fell victim to the Plague of Cyprian (possibly smallpox) and died early in January 270. Before his death, he is thought to have named Aurelian as his successor, though Claudius' brother Quintillus briefly seized power.
Quintillus was declared emperor either by the Senate or by his brother's soldiers upon the latter's death in 270. Eutropius reports Quintillus to have been elected by soldiers of the Roman army immediately following the death of his brother; the choice was reportedly approved by the Roman Senate.
The few records of Quintillus' reign are contradictory. They disagree on the length of his reign, variously reported to have lasted as few as 17 days and as many as 177 days (about six months). Records also disagree on the cause of his death.
When Claudius died, his brother Quintillus seized power with the support of the Senate. With an act typical of the Crisis of the Third Century, the army refused to recognize the new Emperor, preferring to support one of its own commanders: Aurelian was proclaimed emperor about May 270 by the legions in Sirmium.
The first actions of the new Emperor were aimed at strengthening his own position in his territories. Late in 270, Aurelian campaigned in northern Italia against the Vandals, Juthungi, and Sarmatians, expelling them from Roman territory. To celebrate these victories, Aurelian was granted the title of Germanicus Maximus.