The final settlement which began in A.D. 300 between the menacing power of Christianity and the forces of the state, was the unavoidable consequence of a long and slow development. The men who then stood at the head of the Roman Empire were compelled to become the protagonists in the last act of this great drama and, clearly as its final issue may have been indicated from the first, by the positions they adopted materially affected the course of the drama.
As all know, the climax was reached with the conversion of Constantine. Quite recently, however, so eminent a Byzantine scholar as H. Grégoire has disputed the belief that the Battle of the Mulvian Bridge was won in the sign of the Cross, and, as more than one serious student has accepted his view, we shall have to follow in rather closer detail his brilliant description of the political developments of these years. We shall readily admit with him that the account of Eusebius in the Vita Constantini, i, 28–30, is a highly-coloured romance and panegyric, marred by rehandling and later interpolation, and quite inconsistent with the information of Lactantius: yet, despite all this, it has a definite kernel of history in it, as I hope soon to show.