Scapa Flow

Tucked into the Orkney Islands, Scapa Flow is a sheltered sea harbour that Britain relied on as its chief naval anchorage through both world wars. During the First World War it sheltered Admiral Jellicoe's Grand Fleet from 1914 to 1918, and the fleet departed from there to meet the Germans at Jutland in 1916.

Beginning in 1914, the British set about shielding the harbour by fortifying its entrances and then spreading defences across much of Orkney. Boom nets, patrolling warships and minefields reinforced these fixed positions, which together formed what was then the biggest fortified naval base anywhere. When war returned in 1939, the anchorage once again suited the task of confronting the German navy and became home to the Home Fleet. Attacks by aircraft and submarines, one of which sank the battleship Royal Oak, did not stop the work of strengthening the defences. By 1940 Orkney had grown into a fortress island, the most unified defensive system of its type in Europe, garrisoned by as many as 50,000 Commonwealth soldiers.

Naval historian Angus Konstam traces the history of this great naval stronghold, supported by newly commissioned illustrations. Many of its structures can still be seen on the islands today.