We must remember that the Sueones are not mentioned from the time of Tacitus to that of Charlemagne (772–814), and certainly they had not disappeared in the meantime.
What were the Danes doing with their mighty fleets before this? Had their ships been lying in port for centuries? Had they been built for simple recreation and the pleasure of looking at them, or did their maritime power arise at once as if by magic? Such an hypothesis cannot stand the test of reasoning. The turning of a population into a seafaring nation is the work of time. Where in the history of the world can we find a parallel to this story of a people suddenly appearing with immense navies? Let us compare by analogy the statement of the chronicles with what might happen to the history of England in the course of time.
Suppose that for some reason the previous history of England were lost, with the exception of a fragment which spoke of her enormous fleet of to-day. Could it be reasonably supposed that this great maritime power was the creation of a few years?
A few years after the time fixed as that of their first supposed appearance we find these very Danes swarming everywhere with their fleets and warriors, not only in England, but in Gaul, in Brittany, up the Seine, the Garonne, the Rhine, the Elbe, on the coasts of Spain, and further eastward in the Mediterranean.
The Sueones, or Swedes, reappear at the close of the eighth and commencement of the ninth centuries by the side of the Danes, and both called themselves Northmen. Surely the maritime power of the Sueones, described by Tacitus, could not have been destroyed immediately after his death, only to reappear in the time of Charlemagne, when it again becomes prominent in the Frankish annals.
A remarkable fact not to be overlooked is that, in the time of Charlemagne, the Franks and Saxons were not a seafaring people, though their countries had an extensive coast with deep rivers. The Frankish annals never mention a Frank or Saxon fleet attacking the fleets of the Northmen, or preventing them from ascending their streams, though Charlemagne ordered ships to be built in order to resist their incursions.
While the country of the Saxons was being conquered by this Emperor, we find that the Saxons themselves had no vessels on the Elbe or Weser in which, if defeated, they could retire in safety, or by help of which they could prevent the army of their enemies from crossing their streams. Such tactics were constantly used by the Northmen in their invasions of ancient Gaul, Britain, Germania, Spain, &c.
Thus we see that, though hardly more than three hundred years had elapsed since the time when, according to the Roman writers, the fleets of the Franks and Saxons swarmed over every sea of Europe, not a vestige of their former maritime power remained in the time of Charlemagne, and the Saxons were still occupying the same country as in the days of Ptolemy.
Pondering over the above important facts, the question arises: Were not the Romans mistaken in giving the names of Saxons and Franks to the maritime tribes of whose origin, country, and homes they knew nothing, but who came to attack their shores? Were not these so-called Saxons and Franks in reality tribes of Sueones, Swedes, Danes, Norwegians? The Romans knew none of the countries of these people. It seems strange, if not incredible, to find two peoples, whose country had a vast sea-coast and deep rivers, totally abandoning the seafaring habits possessed by their forefathers.
It cannot be doubted that Ivar Vidfadmi, after him Harald Hilditönn, then Sigurd Hring and Ragnar Lodbrok and his sons, and probably some of the Danish and Swedish kings before them, made expeditions to England, and gained and held possessions there. Several distinct records, having no connection with each other, being parts of different Sagas and histories, with the archæology, form the evidence.