From the foregoing it is clear that centuries before the question of _mare clausum_ was raised, important fisheries were established along the east coast of England and Scotland, and that foreign fishermen took part in them. The number of French and Flemish fishermen attending the fishery must have been always great, because they had to furnish a large part of Catholic Europe with fish. But the number was increased after the fourteenth century, and especially in the fifteenth, from two causes. One was the decline of the great herring fishery at Scania, in the Baltic, upon which the Hanseatic League had risen to power and opulence, and which provided perhaps the greater part of continental Europe with salted and smoked herrings--Germany, Poland, Russia, part of France, and even to some extent Flanders and England. The Scanian herrings were esteemed the best, and the Hanse controlled the trade.[103] The other circumstance was the invention in the latter part of the fourteenth century by Beuckelsz, a native of Biervliet, in Zealand, of a greatly improved mode of curing herrings,--an invention which most materially aided the Dutch in taking the place of the Hansards in the herring industry, and in the commerce which it brought in its train. Some of the towns in the Low Countries early belonged to the Hanseatic League, and their fishermen were in the habit of going to the Scanian fishery;[104] but from the fifteenth century at least the herring fishery on the British coasts became by far the most important in Europe. It attracted foreign fishermen in increasing numbers, and gradually the Dutch came to take the leading part in it, displacing the Flemings and the men from Normandy and Picardy, and even to a large extent the English themselves. In 1512 we find Margaret of Savoy appealing to Henry VIII. to protect the fishermen of Holland, Zealand, and Friesland in their herring fishery, in which they were menaced by the Hanseatic towns, which were fitting out vessels to interrupt them; and in her letter she describes the herring fishery as the principal support of these states.[105] Towards the end of the century, when the Dutch had begun to call their herring fishery on the British coast their “great gold mine,” another event occurred which tended still further to strengthen their hold on it by opening fresh markets on the Continent. This was the failure of the great Bohuslän fishery in Sweden, which continued barren for about seventy years.[106] They were also enabled to prosper in their fishery by the beneficent policy of the English sovereigns towards them up to the reign of James I., when the claim to the exclusive fishing in the British seas was put forward on behalf of the crown.