Crossing of the Rhine

31 December 406 is the often-repeated date of the crossing of the Rhine by a mixed group of barbarians that included Vandals, Alans and Suebi. The Rhine-crossing transgressed one of the Late Roman Empire's most secure limites or boundaries, and so was a climactic moment in the decline of the Empire. It initiated a wave of destruction of Roman cities and the collapse of Roman civic order in northern Gaul. That, in turn, occasioned the rise of three usurpers in succession in the province of Britannia. Therefore, the crossing of the Rhine is a marker date in the Migration Period, during which various Germanic tribes moved westward and southward, out of southern Scandinavia and northern Germania.

The full statement of received opinion has been that a mixed band of Vandals, Alans and Suebi crossed the Rhine at Mainz on December 31, 406, and began to ravage Gaul. Several written accounts document the crossing, supplemented by the time line of Prosper of Aquitaine, which gives a firm date of 31 December 406.

A letter by Jerome, written from Bethlehem, gives a long list of the barbarian tribes involved (Quadi, Vandals, Sarmatians, Alans, Gepids, Herules, Saxons, Burgundians, Alemanni and the armies of the Pannonians). Some of them, like Quadi and Sarmatians, are drawn from history or literary tradition. Jerome mentions Mainz first in a list of the cities devastated by the incursion, which is the sole support for the common assumption that the crossing of the unbridged Rhine was effected at Mainz. Jerome lists the cities now known as Mainz, Worms, Rheims, Amiens, Arras, Thérouanne, Tournai, Speyer and Strasbourg as having been pillaged.

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