By the time of Edward III the fishing had become so important to this country that a law was passed forbidding any fisherman to give up his trade; but, in return for this, fishermen and mariners were exempt from serving in any capacity other than that to which they had been bred. By the fourteenth century there were literally thousands of vessels, each having at least six persons on board, fishing for herrings between Denmark and Norway, and more than 300,000 people were in one way or another engaged in the industry. In five days no fewer than sixty foreign ships during one week came into Great Yarmouth for these fish. Thus, side by side with our fishermen there was growing up a carrying trade, herrings and woollen cloth being regularly exported to the continent. By the fifteenth century ships from the British Isles, France, Flanders, Zeeland, Holland and Germany with Scottish herrings used to sail to the Mediterranean to sell the fish for the faithful during Lent. Throughout the Middle Ages the herring-fishing of the North Sea was far and away the most important of western Europe, especially off Scotland, Sweden and Norfolk, whither the Dutchmen came both to use their nets and to buy. The trade in salted and smoked herrings helped to make the wealth of the Hanseatic and Dutch towns. And it is here that we find, in the Hanseatic League, a force which corresponds to that of Venice, Pisa and Genoa in the south; for in developing overseas trade it encouraged the ship and seafaring.