Battle of the Frigidus
394 CE.
Shown on the map at 45.870°, 13.936°.
The Battle of the Frigidus, also called the Battle of the Frigid River, was fought on 5 and 6 September 394 between the armies of the Roman emperor Theodosius the Great and the rebel augustus Eugenius (r. 392–394), in the eastern border of Roman Italy. Theodosius won the battle and defeated the usurpation of Eugenius and Arbogast, restoring unity to the Roman Empire. The battlefield, in the Claustra Alpium Iuliarum near the Julian Alps through which Theodosius's army had passed, was probably in the Vipava Valley – with the Frigidus River being the modern Vipava – or possibly in the valley of the Isonzo. Timasius, the magister militum, commanded the Theodosian army with help from the magister utriusque militiae Stilicho. Arbogast, previously the magister militum under Theodosius's brother-in-law and senior co-emperor Valentinian II (r. 375–392), commanded Eugenius's forces. It was Arbogast who had engineered Eugenius's acclamation after Valentinian's mysterious death. With reinforcements from Theodosius's allies among the Goths led by Alaric and Gainas, and from Bacurius the Iberian, Theodosius's army defeated Eugenius's, and Eugenius was captured and executed.
Text from the Wikipedia article Battle of the Frigidus, licensed CC BY-SA 4.0.