On September 5, 394, a battle began at Frigidus, also known as the Battle of Mrzla Reka (Fluvius frigidus, today the Hubelj stream in Ajdovščina), in which the troops of the Eastern Emperor Theodosius I and the western-Armenian “usurper” Eugenius were fighting. The battle ended the day after the victory of Emperor Theodosius. The Battle of Frigid (probably the Latin name for Vipava) was of great importance, as Christianity thus achieved a great victory over paganism.
The Armed Forces Commander Arbogast, together with the Roman Senate, prepared a rebellion against Emperor Theodosius I, who ruled the Roman Empire from Constantinople. Pagan Arbogast enjoyed the support of the Roman Senate, which had argued for more than two generations with Christian emperors in Constantinople. Christianity in the Roman Empire became a legitimate faith with the Milan edict in 313. The Senate appointed a new emperor, Eugenius, who was seen in Constantinople as a usurper. With more than 20,000 Visigoths, Theodosios flew from Constantinople to the west. The army of the Western Roman Empire consisted largely of Franks and Goths loyal to Arbogast.
The location of the Battle of the Frigidus is controversial, it was probably fought at the foot of the Julian Alps near today’s Vrhpolje in Vipava and the Hubelj stream. For Theodosius, the battle was a complete victory, and for the pagans, a complete defeat. After the battle, Theodosius made Christianity the only legal faith in the empire.
After the battle, Eugenyus surrendered and begged for mercy, but he was nevertheless executed. At first, Arbogast managed to escape into the mountains, then after several days he committed suicide. Archaeological remains have not yet been found at the alleged location of the battle. Nevertheless, in the vicinity of Vrhpolje, a memorial was placed at the place where, according to the tradition, Theodosius prayed for a storm that helped him win the battle. With the victory at Frigid, Theodosius succeeded in consolidating the Roman Empire for a very short time. He died only four months later, in January 395.