Eugenius was a western Roman usurper who ruled from 392 to 394 with the backing of the general Arbogast. His defeat by Theodosius I at the Frigidus ended one of the last major internal struggles of the late fourth-century empire.
Eugenius was elevated as western emperor in 392 after the death of Valentinian II and was supported by the general Arbogast; Theodosius I defeated their forces at the Frigidus in 394, ending Eugenius’s brief regime.
Ian Hughes’ Barbarian and the Throne sets Eugenius within the western imperial crisis of the late fourth century, when the death of Valentinian II allows Arbogast to elevate the scholar and court official as emperor. Eugenius becomes the civilian face of a regime dependent on Arbogast’s military power, and his confrontation with Theodosius I at the Frigidus turns the usurpation into a decisive contest for control of the Roman Empire.