Abstract: This chapter argues that Eustathius of Antioch’s deposition took place in autumn 327 as a result of real or faked evidence of sexual misdemeanour, triggering a reversal by Constantine of his previous ecclesiastical policy. It is suggested that Marcellus wrote his Against Asterius partly in response to this event and to the subsequent return of Eusebius of Nicomedia. It is argued that Marcellus, like Athanasius, was trapped by a summons to the Synod of Tyre in 335 when he refused to accept Arius’ reception back into communion at Jerusalem, despite Constantine’s orders. Marcellus’ trial is examined from the accounts of Sozomen and Eusebius of Caesarea, and his innocence established of the theological charges brought.

Keywords: Eustathius of Antioch, Constantine, Eusebius of Nicomedia, Against Asterius, Athanasius, Synod of Tyre, Arius, Eusebius of Caesarea, Sozomen,