St. Ambrose explains his absence from Milan on the arrival of the Emperor Theodosius after his victory over Eugenius, Arbogastes, a Frankish general, had been set by Theodosius over the troops in Gaul, and determined to gain supreme power in the West. Having removed all who were faithful from the person of the Emperor Valentinian II., he caused him to be murdered, and then to conceal his own purposes caused the rhetorician Eugenius, his private secretary, to be acknowledged Emperor. Ambassadors were sent to Theodosius begging him to acknowledge the new Emperor as his colleague, but he saw through the design, and after two years’ preparation marched into Italy, and defeated the usurper’s troops. Eugenius was beheaded, and Arbogastes killed himself. and after expressing his thankfulness for that success he promises obedience to the Emperor’s will, and while commending his piety urges him to be merciful to the conquered.