ARBOGAST (died 394), a barbarian officer in the Roman army at the end of the 4th century. His nationality is uncertain, but Zosimus, Eunapius and Sulpicius Alexander (a Gallo-Roman historian quoted by Gregory of Tours) all refer to him as a Frank. Having served with distinction against the Goths in Thrace, he was sent by Theodosius in 388 against Maximus, who had usurped the empire of the west and had murdered Gratian, and completely defeated him. Theodosius then appointed him chief minister for his young brother-in-law, Valentinian II. In 392, Valentinian died mysteriously at Vienne (in Gaul) ; Arbo gast named as his successor Eugenius, a rhetorician, and pro claimed himself the champion of paganism. In May, 394, Theo dosius marched against him and defeated him at the battle of the Frigidus. Arbogast escaped to the mountains, where he com mitted suicide (Sept. 8 394). Arbogast appears to have been an energetic statesman and one of the greatest soldiers of the later empire.
See T. Hodgkin, Italy and her Invaders (1892), vol. i. chap. xi. and note at end.