Thirty-nine years after the battle of the Wall, on the last day of the Year of Our Lord 406, the Rhine River froze solid during the coldest winter in memory. Hundreds of thousands of waiting Vandals, Alans, Suevi, and Burgundians emerged from the forests of Germania and marched across the ice into Gaul.
A thin and dispirited Roman and Frankish army mustered to meet them but was easily brushed aside. With that, the world was open to pillage.
Some of the barbarian invaders claimed new lands in Gaul. Others struck south toward Italy, Spain, and Africa. In 410, the Gothic warlord Alaric sacked Rome. It was the first conquest of the city in eight centuries.
In that same year as the sacking, the province of Britannia sent an urgent plea to the emperor Honorius to seek military assistance against barbarian invasion.
The inheritor of Caesar replied that the island would have to look to itself.
No other communication from the empire was ever received.