THE NORTHERN BARRAGE

Codenamed Operation SN, the Royal Navy laid a huge minefield in the North Atlantic that ultimately failed to prevent German naval activity against Allied vessels

Shortly before the Second World War broke out, the United Kingdom began to look to its naval defences. Haunted by the German U-boat campaigns against Allied shipping during the First World War, many in the British establishment (including Winston Churchill) believed that enemy attacks on merchant shipping could again be a serious danger.

Owing to German rearmament during the 1930s, updated U-boats were far more advanced than the Royal Navy’s arsenal of anti-submarine countermeasures. As a result, in July 1939 the British decided to lay a huge defensive minefield between the territorial waters of the UK and Norway. Known as the Northern Barrage it would theoretically restrict German naval access to Allied shipping lanes in the Atlantic.

The Northern Barrage was a recreation of the First World War North Sea Mine Barrage that had been primarily laid by the US Navy. During June-October 1918, the Americans (assisted by the Royal Navy) laid over 70,000 mines in an area between the Orkney Islands and Norwegian coast. Yet despite the quantity of mines and the geographical size of the minefield, only four U-boats were sunk, with a further four possibly destroyed. Hundreds of Allied minesweepers were then required to clear the area in 1919.