The second Cæsar whom he created was of distinguished birth. He was Constantius Chlorus, great-nephew, on his mother's side, to the emperor Claudius II. The empire was governed by these four princes; an association which might have produced four civil wars a year, but Diocletian knew so well how to be master of his colleagues, that he obliged them always to respect him, and even to live united among themselves. These princes, with the name of Cæsars were in reality no more than his subjects. It is seen that he treated them like an absolute sovereign; for when the Cæsar Galerius, having been conquered by the Persians, went into Mesopotamia to give him the account of his defeat, he let him walk for the space of a mile near his chariot, and did not receive him into favor until he had repaired his fault and misfortune. Galerius retrieved them the year after, in 297, in a very signal manner. He vanquished the king of Persia in person. These kings of Persia had not been cured, by the battle of Arbela, of carrying their wives, daughters, and eunuchs along with their armies. Galerius, like Alexander, took his enemy's wife and all his family, and treated them with the same respect. The peace was as glorious as the victory. The vanquished ceded five provinces to the Romans, from the sands of Palmyra to Armenia. Diocletian and Galerius went to Rome to dazzle the inhabitants with a triumph till then unheard of. It was the first time that the Roman people had seen the wife and children of a king of Persia in chains. All the empire was in plenty and prosperity. Diocletian went through all the provinces, from Rome to Egypt, Syria, and Asia Minor. His ordinary residence was not at Rome, but at Nicomedia, near the Euxine Sea, either to watch over the Persians and the barbarians, or because he was attached to a retreat which he had himself embellished. It was in the midst of this prosperity that Galerius commenced the persecution against the Christians. Why had he left them in repose until then, and why were they then ill treated? Eusebius says that a centurion of the Trajan legion, named Marcellus, who served in Mauritania, assisting with his troop at a feast given in honor of the victory of Galerius, threw his military sash, his arms, and his branch of vine, on the ground, and cried out loudly that he was a Christian and that he would no longer serve pagans--a desertion which was punished with death by the council of war. This was the first known example of the famous persecution of Diocletian. It is true that there were a great number of Christians in the armies of the empire, and the interest of the state demanded that such a desertion should not be allowed. The zeal of Marcellus was pious, but not reasonable. If at the feast given in Mauritania, viands offered to the gods of the empire were eaten, the law did not command Marcellus to eat of them, nor did Christianity order him to set the example of sedition.