occupation of Roman Gaul, the Scandinavian invaders were men of the sea and migrated in ships. The deep fjords of Norway and the indented coast of the North Sea and the Baltic made them perforce sailors and fishermen and taught them the mastery of the wider ocean. In their dragon ships—shallow, clinker-built, half-decked craft, pointed at either end, low in the middle, where the gunwale was protected by a row of shields—they could cross the sea, explore creeks and inlets, and follow the course of rivers far above their mouth. The greater ships might reach the length of seventy-five feet and carry as many as one hundred and twenty men, but these were the largest, and even these offered but a slow means of migration. We must think of the whole movement at first as one of small and scattered bands, terrible more for their fierce, sudden, and skilful methods of attack, than for force of superior numbers or organization. The truth is that sea-power, whose strategic significance in modern warfare Admiral Mahan did so much to make us appreciate, was in the ninth and tenth centuries, so far as western Europe was concerned, a Scandinavian monopoly. Masters of the seas, the Northmen harried the coasts and river-valleys as they would, and there was none to drive them back.
Outside of the Baltic, where the Danes ravaged the southern coast and the Swedes moved eastward to lay the foundations of the Russian state and to penetrate
