Like as the Norman still is to the Northman, the effects of a settlement of Normans are utterly different from the effects of a settlement of Northmen.
In its lower course, whatever is worthy of record clusters round the historical vicissitudes of Hamburg - its early prominence as a missionary centre (Ansgar) and as a bulwark against Slav and marauding Northman, its commercial prosperity as a leading member of the Hanseatic League, and its sufferings during the Napoleonic wars, especially at the hands of the ruthless Davotit.
Mission work commenced in Bulgaria during the latter part of the 9th century; thence it extended to Moravia, where in 863 two Greek missionaries - Cyril and Methodius - provided for the people a Slavonic Bible and a Slavonic Liturgy; thence to Bohemia and Poland, and so onwards to the Russian kingdom of Ruric the Northman, where about the close of the 10th century the Eastern Church " silently and almost unconsciously bore into the world her mightiest offspring."
On the other hand, the language of the warlike invader or peaceful immigrant may yield, in a few generations, to the tongue of the mass of the population, as the Northman's was replaced by French, and modern German gives way to English in the United States.
But both Celt and Northman acknowledged the polity of Eugenius, and it was chiefly in the matters of tithe, Peter's pence, canonical degrees and the observance of festivals that Rome had still victories to gain.