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
British home army in the First World War an invasion, going so far as to inform the War Office in February that the loss of so many of his troops to the field army overseas absolved him of the responsibility for home defence. Admiral John Fisher, a former First Sea Lord, was concerned about the increasing U-boat menace, and believed that the German war leader, Field Marshall Paul von Hindenburg, would be willing to risk the High Seas Fleet in an invasion attempt. The Admiralty regarded the risk as possible rather than probable, and guaranteed to be able to disrupt an enemy fleet within 32 to 36 hours