The authority of Magnentius was acknowledged through the whole extent of the two great praefectures of Gaul and Italy; and the usurper prepared, by every act of oppression, to collect a treasure, which might discharge the obligation of an immense donative, and supply the expenses of a civil war.

The martial countries of Illyricum, from the Danube to the extremity of Greece, had long obeyed the government of Vetranio, an aged general, beloved for the simplicity of his manners, and who had acquired some reputation by his experience and services in war.

Attached by habit, by duty, and by gratitude, to the house of Constantine, he immediately gave the strongest assurances to the only surviving son of his late master, that he would expose, with unshaken fidelity, his person and his troops, to inflict a just revenge on the traitors of Gaul.

But the legions of Vetranio were seduced, rather than provoked, by the example of rebellion; their leader soon betrayed a want of firmness, or a want of sincerity; and his ambition derived a specious pretence from the approbation of the princess Constantina.

That cruel and aspiring woman, who had obtained from the great Constantine, her father, the rank of Augusta, placed the diadem with her own hands on the head of the Illyrian general; and seemed to expect from his victory the accomplishment of those unbounded hopes, of which she had been disappointed by the death of her husband Hannibalianus.