Hereward the Last of The English by Charles Kingsley

It has been shown how the Count of Guisnes had been a thorn in the side of Baldwin of Lille, and how that thorn was drawn out by Hereward. But a far sharper thorn in his side, and one which had troubled many a Count before, and was destined to trouble others afterward, was those unruly Hollanders, or Frisians, who dwelt in Scaldmariland, "the land of the meres of the Scheldt. " Beyond the vast forests of Flanders, in morasses and alluvial islands whose names it is impossible now to verify, so much has the land changed, both by inundations and by embankments, by the brute forces of nature and the noble triumphs of art, dwelt a folk, poor, savage, living mostly, as in Caesar's time, in huts raised above the sea on piles or mounds of earth; often without cattle or seedfield, half savage, half heathen, but free. Free, with the divine instinct of freedom, and all the self-help and energy which spring thereout.

They were a mongrel race; and, as most mongrel races are (when sprung from parents not too far apart in blood), a strong race; the remnant of those old Frisians and Batavians, who had defied, and all but successfully resisted, the power of Rome; mingled with fresh crosses of Teutonic blood from Frank, Sueve, Saxon, and the other German tribes, who, after the fall of the Roman Empire, had swept across the land.