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
Naval warfare of World War I included those at Heligoland Bight (two of them), Dogger Bank, and Jutland. Though British tactical success remains a subject of historical debate, Britain accomplished its strategic objective of maintaining the blockade and keeping the main body of the High Seas Fleet in port for the vast majority of the war. The High Seas Fleet remained a threat as a fleet in being that forced Britain to retain a majority of its capital ships in the North Sea. The set-piece battles and maneuvering have drawn historians' attention; however, it was the naval blockade of food and raw material imports into Germany