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
European theatre of World War I convoy system in early 1917. There was one great battle in the waters near Europe: the Battle of Jutland 31 May 1916 – 1 June 1916 between the German High Seas Fleet and the British Grand Fleet. This was one of the largest sea battles in world history though, in some respects, the battle was inconclusive. In the Adriatic, some very limited sea combat took place between the navy of Austria-Hungary and the Allied navies of France, Britain, and Italy. The strategy of the Allies was to blockade the Adriatic and monitor the movements of the Austrian fleet. In general,