Compared with the classical historians he emulates, Ammianus Marcellinus represents few speeches in oratio recta, and they are comparatively limited in speaker, occasion, and form. Yet scholars have been too quick to dismiss Ammianus’ speeches as a meaningless vestige of an outmoded generic code. I argue that they represent a new method of incorporating speeches into historical narrative that is more adequate to the political discourse of the fourth century. The paper tests this hypothesis through a close examination of the four speeches Ammianus gives to Constantius II, demonstrating that they are subtle tools for measuring the emperor’s subjective merit against objective standards of imperial legitimacy.La revanche de Vetranio ? La proues...