History of Orkney should continue to be observed in Orkney and Shetland. Thus the udal succession and mode of land tenure (that is, absolute freehold as distinguished from feudal tenure) lingered to some extent, and the remaining udallers held their lands and passed them on without written title. The islands cluster round the huge deep-water anchorage of Scapa Flow like a protecting hand, and in both World War I and World War II, the Royal Navy had a major base there, enabling them to challenge any attempt by German warships to emerge into the ocean through the Norwegian Sea. After the Armistice in
History of the North Sea heightened in 1904 by the Dogger Bank incident. However, the British did not face a challenge to their dominance of the North Sea until World War I broke out in 1914. During the First World War the North Sea became the main theatre of the war for surface action. The Second World War also saw action in the North Sea, though it was restricted more to submarines and smaller vessels such as minesweepers, and torpedo boats and similar vessels. After the war, the North Sea lost much of its military significance because it is bordered only by NATO member-states. However,