Marcus Aurelius Valerius Claudius was born on 10 May AD 214 in the region of Dardania which was either a part of the province of Illyricum or Upper Moesia.
Claudius seems to have played a major part in the conspiracy to assassinate Gallienus outside Mediolanum (Milan) in September AD 268. At the time he was based close by at Ticinum, in command of a military reserve.
It was announced that emperor Gallienus, as he lay dying, had formally appointed Claudius as his successor.
This mildness of Claudius II showed itself immediately after Gallienus' death. The senate, pleased at hearing that Gallienus, whom many of them despised, was dead, turned on his friends and supporters. Several were killed, including Gallienus' brother and surviving son. But Claudius II intervened, asking for the senators to show restraint against Gallienus' supporters and for them to deify the late emperor, in order to help sooth the angered troops.
The new emperor continued the siege of Mediolanum (Milan). Aureolus tried to sue for peace with the new ruler, but was rejected. Alas he surrendered, hoping for mercy, but was soon afterwards put to death.
But Claudius II's task in the north of Italy was far from over. The Alemanni had, whilst the Romans were fighting each other at Milan, broken through the Brenner Pass across the Alps and were now threatening to descend into Italy.
Next the emperor, having stayed the winter in Rome, turned his attention to the Gallic empire in the west. He sent Julius Placidianus to lead a force into southern Gaul, which restored the territory east of the river Rhône back to Rome. Also he opened talks with the Iberian provinces, bringing them back into the empire.
Under Claudius II Gothicus the tide was turning back in Rome's favour against the barbarians. The emperor's military skill enabled him to follow up Gallienus' success at the battle of Naissus (AD 268) and was instrumental in reestablishing Roman authority.
Was Claudius II Gothicus' performance against the northern barbarians a success, he simply could not afford to deal with the eastern menace of queen Zenobia of Palmyra. The widow of Gallienus' ally Odenathus, broke with Claudius II in AD 269, and attacked Roman territories.
But Claudius II Gothicus, still occupied with driving the Goths out of the Balkans, could ill afford to deal with the powerful kingdom arising in the east.
Claudius II Gothicus had not even been emperor for two years, but his death caused great grief among the army as well as the senate. He was immediately deified.