In 378 the Romans suffered a major defeat at the
Battle of Adrianople, which was caused by a sudden movement of peoples including
Goths,
Alans and
Huns coming from present-day Ukraine to the east. The emperor
Valens died in the defeat. According to
Ammianus, the Pannonian region was among the areas first affected by "a savage horde of unknown peoples, driven from their abodes by sudden violence". By 380, one of the armed groups responsible for the defeat, led by
Alatheus and Saphrax who were wards of the underage king of the
Greuthungi Goths, entered the Pannonian part of the Roman empire with the permission of emperor
Gratian, while his new co-emperor Theodosius was out of action with a serious illness. Also in about 380, Jordanes mentions that the Vandals, perhaps those in Pannonia, made an invasion which caused the surviving emperor Gratian to move into Gaul. It is possible that the Vandals invaded Gaul itself already during this period. After the death of emperor
Theodosius I in 395,
Saint Jerome listed the Vandals and their long-time neighbours the Quadi and Marcomanni, together with several of the new eastern peoples who were causing devastation in the Roman provinces stretching from
Constantinople to the
Julian Alps, including Dalmatia, and all the provinces of Pannonia: "Goths and Sarmatians, Quadi and Alans, Huns and Vandals and Marcomanni". The poet
Claudian described them crossing the frozen Danube with wagons, and then setting wagons rigged around themselves like a wall at the approach of the Roman commander Stilicho. He says that all the fertile lands between the
Black Sea and
Adriatic were subsequently like uninhabited deserts, specifically including Dalmatia and Pannonia. At the same time, the Gothic general
Alaric I, who had loyally served with his Gothic troops under Theodosius I at the
Battle of Frigidus only a few months early, was beginning his rebellion, and started leading his army south, first towards Constantinople, and later towards Greece. This was triggered by internal Roman conflicts after the death of Theodosius. While some later writers blamed Stilicho, Claudian claimed that they were all incited by an Eastern Roman consul and enemy of Stilicho,
Rufinus. The exact connection between Alaric and those peoples Claudian mentioned crossing the Danube remains unclear. In 401, Claudian described how
Raetia was troubled by the local
Vindelici while Stilicho was preoccupied in Italy with the invasion of Alaric, the Gothic military leader from inside the empire. According to Claudian, non-Roman peoples (
gentes) broke their treaties (
foedera) and, encouraged by the news of trouble in Italy, they seized parts of Roman
Vindelicia (in
Raetia) and
Noricum. The text says that Stilicho's victorious forces earned "Vandal spoils" (
Vandalicis ... spoliis), and so assuming he was not referring to the local
Vindelici, many scholars believe Vandals were involved. Furthermore, there are proposals that they included the same Vandal groups who later went to Hispania, including both Silingi and Hasdingi Vandals. Some scholars have interpreted this to mean that Vandals had already moved westwards up the Danube, and closer the Rhine. In 406, the year of the Rhine crossing of the Vandals and Alans,
Radagaisus, a Gothic leader from outside the empire, attacked Italy with a very large force from the Pannonian area. By August he was defeated. Modern scholars have proposed various connections between these events and the movement subsequent westwards of the Vandals and others into Gaul. In any case, at the end of 406, the Hasdingi Vandals participated together with Silingi Vandals and
Sarmatian Alans in an historic
crossing of the Rhine, entering Roman Gaul. The king of the Hasdingi,
Godigisel, lost his life
in battle against the
Franks, who attempted to block the crossing into Gaul.
Gregory of Tours cited a text of
Frigeridus, which claimed that 20,000 front-line Vandal troops fell, and the Alans led by King
Respendial retreated at first, but then saved the Vandal nation from being destroyed, by coming to their rescue. Another Alan King,
Goar, joined the Romans, and was subsequently settled in Gaul. According to the version of Jordanes, the Hasdingi were summoned to Gaul by the Roman military leader
Stilicho, who was reputed to have Vandal origins, and once there they were a mobile group who plundered Roman Gaul. In another letter by Saint Jerome from 409, many of the Pannonian peoples, including Roman Pannonians, were confirmed as invaders occupying Roman Gaul at that time: "Quadi, Vandals, Sarmatians, Alans, Gepids, Herules, Saxons, Burgundians, Allemanni and—alas! for the commonweal!—even Pannonians". ==Spain and Africa==