Publius Gallienus

Publius Gallienus (died 268), emperor of Rome (253-268). He was made joint ruler on the accession of his father, Valerian, in August 253. In 258 Gallienus defeated the Alamanni, a group of German peoples who were making incursions into the Roman provinces along the Danube. The Alamanni rose again, however, and forced their way into Italy, where Gallienus gained a second victory over them near Mediolanum (now Milan). Meanwhile, Valerian had been engaged in wars with Shapur I, the Sasanian king of Persia (reigned 241-272), by whom he was taken prisoner in 260 and put to death. Gallienus then became sole emperor, but in name only, since numerous other rulers were proclaimed in outlying parts of the Roman Empire. Gallienus established a highly mobile cavalry that remained part of the empire's military force under his successors. During an attack on Mediolanum, held by a usurper, Gallienus was killed in a plot instigated by some of his officers. He was succeeded by Claudius II, his cavalry commander.