Now when Alexander, the Roman emperor, had brought his rule to an end after thirteen years, Maximin Caesar succeeded him; who, out of spite against the house of Alexander, which was composed for the most part of believers, raised a persecution, ordering that the rulers of the churches alone be put to death, as being responsible for the teaching according to the gospel. At that time also Origen composed his work On Martyrdom, dedicating the treatise to Ambrose and to Protoctetus, a presbyter of the community at Caesarea; for no ordinary distress had overtaken them both in the persecution, in which it is recorded that these men were distinguished for their confession, the reign of Maximin lasting no more than three years. Origen has noted this particular time of the persecution in the twenty-second of his Expositions on the Gospel according to John, and in various letters.