Greater ships were afterwards built and improvements made in the shape and size of the sails and spars used, and the number of masts was increased. * * * * * Meanwhile in the Far North a seafaring nation was proving its worth. The wild men of the wilder North, the Danes, the Scandinavian Vikings--turbulent, adventurous and fierce, to whom fear was a word unknown--animated by the virile yet mystic mythology of the North, and inspired by the love of conquest and travel, now began to play their part in the world’s naval history. The Vikings produced the “long ship,” the “serpent,” daring in conception, marvellous in construction, possessing wonderful qualities as a sea-boat, fast under sail or oar, and of a beauty of outline and shape hardly to be excelled even now. Such were the vessels in which the Danes invaded England, and by building vessels as good as those of the Danes, and some rather better, King Alfred repulsed the invaders and implanted in the English that “habit of the sea” they have never lost. But the lesson of the Norsemen was destined to lie dormant for many a long year. Although the Romans had introduced the “long ship” for war purposes--so-called because it was longer in proportion to its beam than the merchant ships--the Mediterranean shipbuilders preferred as a whole to retain the heavy hull, and the form they believed best suited to their needs upon the tideless sea. Slave power was cheap, and was to be had for the trouble of capturing, and for many centuries oar-driven galleys were preferred over any vessel dependent upon sails only, and were to be found in the Mediterranean as late as the beginning of the nineteenth century. As ships of greater size were provided in the Middle Ages, huge erections in the shape of castles were added at the bow and stern: great, unwieldy craft which contemporary historians likened to floating islands. The Venetian and Genoese republics elevated the art of constructing oared galleasses to its highest, and ere long Spain took the lead in producing warships with dimensions and power of armament which made her the chief maritime power of the world. * * * * *