B. 2.--The old heathen worship still continued side by side with the new Faith; but signs soon appeared that the Church would tolerate no such rivalry when once her power was equal to its suppression. Julius Firmicus (who wrote against "Profane Religions" in 343) implores the sons of Constantine to continue their good work of stripping the temples and melting down the images;--in special connection with a visit paid by them that year to Britain[337] (our last Imperial visit), when they had actually been permitted to cross the Channel in winter-time; an irrefragable proof of Heaven's approval of their iconoclasm. It is highly probable that they pursued here also a course at once so pious and so profitable, and that the fanes of the ancient deities but lingered on in poverty and neglect till finally suppressed by Theodosius (A.D. 390). B. 3.--And now Britain resumed her _rôle_ of Emperor-maker.[338] After the death of Constans, (A.D. 350), Magnentius, an officer in the Gallic army of British birth, set up as Augustus, and was supported by Gratian, the leader of the Army of Britain, and by his son Valentinian. Magnentius himself had his capital at Treves, and for three years reigned over the whole Prefecture of the Gauls. He professed a special zeal for orthodoxy, and was the first to introduce burning, as the appropriate punishment for heresy, into the penal code of Christendom. Meanwhile his colleague Decentius advanced against Constantius, and was defeated, at Nursa on the Drave, with such awful slaughter that the old Roman Legions never recovered from the shock. Henceforward the name signifies a more or less numerous body, more or less promiscuously armed, such as we find so many of in the 'Notitia.' Magnentius, in turn, was slain (A.D. 353), and the supreme command in Britain passed to the new Caesar of the West, Julian "the Apostate." B. 4.--Under him we first find our island mentioned as one of the great corn-growing districts of the Empire, on which Gaul was able to draw to a very large extent for the supply of her garrisons. No fewer than eight hundred wheat-ships sailed from our shores on this errand; a number which shows how large an area of the island must have been brought under cultivation, and how much the country had prospered during the sixty years of unbroken internal peace which had followed on the suppression of Allectus.