VALERIUS, b. in humble life near Salons, in Dalmatia, 245 A.D., inherited from his mother, Dioclea, the name of Diodes, which he afterwards enlarged into D., and attached as a cognomen to Valerius, a name of the most patrician associa tions. He adopted a military career, and served with distinction under Probes and Aurelian, accompanied Carus on his Persian campaign, and finally, on the murder of Numeriamis having been discovered at Chalcedon, he was proclaimed emperor in 284 by the army on its homeward march. The suspected assassin of Numerianus, the pre fect, Arrius Aper, lie slew with his own hands, in order, it is alleged, to fulfill a prophecy communicated to him, while still a lad, by a Druidess of Gaul, that lie should accede to a throne as soon as he had killed an apex (wild-boar). In 2S5, D. commenced hostilities against Carinus (the joint-emperor along with the deceased Numerianus), who, although victorious in the decisive battle that ensued, was murdered by his own officers, thus leaving to D. the undisputed supremacy. His first years of government were so molested by the incursions of barbarians, that, in order to repel their growing aggressiveness, ho took to himself a colleague—namely, Maximianus—who, under the title of Augustus, became joint-emperor in 286. D. reserved for himself the charge of the eastern empire, and gave the western to Maximian. Still the attacks of the barbarians continued as formidable as ever. The empire was menaced by the Persians in the e., by the Germans and other barbarians in the w. ; and in order to provide for its permanent security, D. subjected it to a still further division. In 292, Constantius Chlorus and Galerius were proclaimed as Caesars, and the distribution of the Roman empire was now fourfold: D.
taking the e., with Nicomedia as his seat of government; Maximian, Italy and Africa, with Milan as his residence; Constantius, Britain, Gaul, and Spain, with Treves as his headquarters; Galerius, Illyricum, and the entire valley of the Danube, with Sirmium as his imperial abode. It was upon his colleagues that most of the burden of engaging actively in hostilities fell, as D. seldom took the field in person. Among the conquests, or rather re-conquests. that were made under his rule, may be enumerated that of Britain, which, after maintaining independence under Carausius and Allectus, was, in 296, restored to the empire; that of the Persians, who were defeated, and compelled to capitulate in 298; and that of the Marcomanni, and others of the northern barbarians. who were driven beyond the Roman frontier. D., after 21 years' harassing tenure of government, desired to pass the residue of his days in tranquillity. On the 1st of May, 305, accordingly, he abdicated the imperial throne at Nicomedia, and compelled his colleague, Maximian (much against the latter's will), to do likewise at Milan. D. sought retirement. iu his native province of Dalinatia, and for 8 years resided at Salona (see SPALATO), devoting himself to philosophic reflection, to rural recreation, and to horti cultural pursuits. Two years before his abdication, lie was instigated by his colleague, Galerius, to that determined and sanguinary persecution of the Christians for which his reign is chiefly memorable. He died in 313