It is not to the Anglo-Saxon period of our history that we must look for the origin of the claims of England to the sovereignty of the sea, even in a purely military sense. At that time, for at least three centuries before the Norman Conquest, the Northmen and not the English were the real lords and masters of the sea. They offered an example of what is now so much spoken of as the influence of sea-power on history that is unsurpassed in later annals. Their leaders were styled sea-kings for the best of reasons. Their fleets darkened every coast from within the Arctic circle to the furthermost bounds of the Mediterranean. Through their command of the sea they took permanent possession of the larger part of England; they penetrated almost every great river in Europe--the Elbe, the Schelde, the Rhine, the Seine; they formed settlements from Friesland to Bordeaux; they discovered and planted colonies in Iceland (A.D. 861), Greenland (A.D. 985), and North America (A.D. 861); and they founded kingdoms or dynasties not only in England, but in France, Sicily, Ireland, and Russia.[27] In the presence of such irrepressible energy in maritime and warlike enterprises the English were not able to hold their own on the sea, far less to acquire dominion over it. It is not until a considerable time after the Norman Conquest that valid evidence is to be found of the English claim to the sovereignty of the sea. Although obscurity surrounds the precise time and mode in which the pretension took its rise, there is little doubt that it originated in the period following the Conquest. The shores on both sides of the Channel were then brought under the same dominion. In the reign of Henry I. almost the whole of the Atlantic coast of France from Flanders to the Pyrenees was in the possession of the English crown, and for about four and a half centuries, until the loss of Calais in 1558, England held more or less territory in France. The Channel thus became in effect an English sea--the narrow sea--intervening between the continental and insular territories of the king, and it acquired high importance as the passage from one part of the realm to the other. It was in this connection and for the guarding of the coasts that the organisation of the Cinque Ports was developed by the Norman and Angevin kings.[28] Even after the loss of the French provinces, the continued possession of the Channel Islands and the usual possession of Calais kept alive the English claim to the narrow sea. The Conquest was, moreover, followed by a great increase in the stream of traffic between the two countries,[29] while fishermen from Normandy and Picardy, as well as from Flanders, came in large and increasing numbers to take part in the great herring fishery along the east coast of Scotland and England.