The plague which began in the reign of Justinian, as it was more violent than any recorded in history, so it was preceded by wars equally unexampled. The Romans had indeed for ages employed themselves in war; but, by their constant superiority to every adversary, their empire had become so amazingly extensive, that, whatever wars were carried on in the remote provinces, the great body of the empire always remained at peace; and this was the case even in their most violent civil wars. On the accession of Alexander Severus, about the year 232, they began to encounter enemies so numerous and formidable, that all their power proved insufficient to repel them. In the tenth year of Alexander’s reign, the Persians, having overthrown the ancient empire of the Parthians, turned their arms against the Romans, and, though frequently defeated at that time with great slaughter, renewed their incursions in the reign of Gordian, about the year 242, when they were in like manner defeated and obliged to retire. As these defeats, however, did not at all affect the strength of the Persian empire, the Romans still found them as formidable enemies as ever; while the Goths, Sarmatians, Franks, and other northern nations, harassed them in other parts. In the reign of Decius, who ascended the throne in 249, they became extremely formidable, insomuch that the emperor himself, with his whole army, was at last cut off by them. The consequence of this was, that the empire was instantly invaded in many different parts, and, though the barbarians were at times defeated, we never find that the empire regained its former tranquillity. The Persians and Scythians, taking advantage of the general confusion, invaded the provinces next them, while the finishing stroke seemed to be given to the Roman affairs by the defeat and captivity of Valerian by the Persians.