The Epistle of the Bishops against Paul
21 But as he was about to do it, and was, so to speak, in the very act of signing the decrees against us, the divine judgment came upon him and restrained him at the very verge of his undertaking, showing in a manner that all could see clearly, that the rulers of this world can never find an opportunity against the churches of Christ, except the hand that defends them permits it, in divine and heavenly judgment, for the sake of discipline and correction, at such times as it sees best.
22. After a reign of six years, Aurelian was succeeded by Probus. He reigned for the same number of years, and Carus, with his sons, Carinus and Numerianus, succeeded him. After they had reigned less than three years the government devolved on Diocletian, and those associated with him. Under them took place the persecution of our time, and the destruction of the churches connected with it.
23. Shortly before this, Dionysius, bishop of Rome, after holding office for nine years, died, and was succeeded by Felix.
Source: Church History (New Advent)