During the third century the empire was agitated by numerous competitions for the purple, but it was somewhat appeased on the accession of Diocletian. The legions in Britain now adopted the practice of setting up emperors of their own. One of them, Carausius, reigned from 287 to 294, and was only got rid of by assassination. The murderer, Allectus, attempted to succeed him, and maintained himself in the island till defeated by Constantius, who was created a sub-emperor, with the title of Cæsar; thus Britain was once more united to the empire. The victor made himself loved by the Britons, by his equitable and wise administration, and continued to reside amongst them till the abdication of Diocletian. At his death, which occurred in York in 306, he recommended to the army, who were devoted to him, his son, the celebrated Constantine, who was immediately saluted emperor and Augustus. He was beloved by the Britons, being the son of a British mother, the "fair Helena of York." Constantine was a Christian, but, before his accession, had been compelled to execute the imperial commands against the followers of that faith. Many of the Romans, who had received the new religion, and fled from the persecutions of Claudius and Nero, found refuge in Britain, where the imperial edicts were less rigorously obeyed, till the persecution of Diocletian, when the churches throughout the empire were ordered to be closed, and the refusal of the new sect to offer sacrifice to the gods of Rome was punished with death. Much as Constantine condemned, he dared not annul the impious mandate he had received. Ascending his tribunal, before which the principal officers of his army and household had been summoned, he read aloud the edict, and added that those who professed the new faith must decide on abandoning either their faith or their employments. Many, doubtless, chose the former alternative; since we are told that the prince, in great indignation, dismissed the apostates from his service, observing that it was impossible for him to trust those who had denied their convictions. His lieutenants, however, were less scrupulous, and Christian blood was shed to maintain the State religion of the empire. Alban, the protomartyr, as the latter designation implies, was the first who suffered; and the names of Julius and Aaron, citizens of Caerleon, upon the Usk, have also been handed down to posterity as two of the earliest victims. But on the accession of Constantine to the throne, religious toleration was restored throughout the empire. Christianity now made rapid progress in the island. A hierarchy became established, and at the Council of Arles, in 314, three English bishops assisted--those of York, London, and Camulodunum.