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 Empire ' s most secure " limines " or boundaries , a climactic moment in the decline of the Roman Empire that initiated a wave of destruction of Roman cities and the collapse of Roman civic order in northern Gaul , and that occasioned the rise of three usurpers in succession in the province of Britannia ; hence the crossing of the Rhine is a marker date in the Migrations Period . 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 of Jerome written from Bethlehem , which gives a long list of the barbarian tribes involved , some of them , like Quadi and Sarmatians , drawn from history or literary tradition , mentions Mainz first in a list of the cities devastated by the incursion ; this 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 . The initial gathering of barbarians on the east bank of the Rhine has been interpreted as a banding of refugees from the Huns or the remnants of Radagaisus ' defeated Goths , without direct evidence . A frozen Rhine , making the crossing easier , is not attested by any contemporary , but was a plausible surmise of Edward Gibbon . On the east bank , the mixed band of Vandals and Alans fought a raiding party of Franks . The Vandal king Godigisel was killed , but the Alans came to the rescue of the Vandals , and once on the Roman side , they met with no organized resistance . Stilicho had depleted the garrisons in 402 to face Alaric in Italy . Zosimus ' " New History " ( vi . 3 . 1 ) imputes the usurpation of Marcus in Britannia to a reaction to the presence of barbarians in Gaul in 406 ; from a fragment of Olympiodorus , the acclamation as Emperor of Marcus , the first of the Romano - Britannic usurpers , took place that same summer . 406 or 405 ? An article by Michael Kulikowski , finding that " the sequence of events bristles with technical difficulties " , bypassed modern historians ' accounts , which he found depended upon Edward Gibbon and one another , to reanalyse the literary sources ; his conclusion was that a date for the mid - winter crossing of the Rhine of 31 December 405 offers a more coherent chronology of events in Belgica , Gaul and Britannia . Kulikowski outlined how the year 406 came to be selected . The date 31 December 406 is firmly offered by Prosper of Aquitaine in his year - by - year chronicle : " In the sixth consulship of Arcadius and Probus , Vandals and Alans came into the Gauls , having crossed the Rhine , on the day before the kalends of January . " The sixth consulship of Arcadius , with Probus as co - consul , corresponds to 406 . Prosper noted the invasion of Italy by Radagaisus as the prime event of the previous year , and correctly assigned to the year following ( 407 ) the usurpation of Constantine III . " The three entries are linked , and together they tell a kind of story , " Kulikowski observes " Prosper was writing a chronicle , and the genre abhorred blank years . Since his chosen genre demanded an entry for each of three years , Prosper simply portioned out his sequence of events , one event to the year . He does the same thing elsewhere in the chronicle . " With the traditional date of 31 December 406 in mind , much has been made of the inaction of Stilicho , sometimes imputed to his strategy focussed on ambitions in Illyria . Kulikowski ' s date of 31 December 405 finds Stilicho fully occupied in Tuscia battling the forces of Radagaisus , who was not finally overcome and executed until August 406 . It also places the acclamation of the first of the usurpers in Britannia , characterised as a fearful reaction to the barbarian presence in Gaul , " after " the crossing of the Rhine .