Defence Expansion & the War in the North Sea

Prime Minister Winston Churchill visiting Scapa Flow during the Second World War - Orkney Library Archive ref. L208-2

Following a conference held by Sir Winston Churchill, recently appointed 1st Lord of the Admiralty, to try and resolve concerns over the lack of air and submarine defences around the Fleet anchorage, the War Office initiated Plan Q, the strategic army defence plan for the protection of the Fleet Base (TNA: ADM116/5790 p.402). This scheme, and the much more extensive inter-service Plan R, which superseded it in December 1939, was responsible for the posting of thousands of personnel to Hoy during WWII. It is the vast array of defence, supply, domestic and administrative sites that were constructed as a direct result of these plans that now form the backbone of the archaeological legacy surviving on Hoy today.

Plan R, which called for significant increases to the defences against sea attack as well as from the air, transpired as a response to the dramatic events of October 1939. The second month of the war brought Großadmiral Raeder’s energetic campaign against British Naval and merchant shipping in the North Sea to the shores of Scapa Flow. Since the outbreak of WWII, Britain had been subjected to a ‘double pole’ naval strategy that Raeder had been formulating since 1937 (Bird, K., 2006 p.117 & 128). This strategy, which could be paralleled to Blitzkrieg in terms of its speed, called for quick action to maximise the advantage of Britain’s ill preparation for war. Through offensive manoeuvres against merchant shipping, isolated units of the British Navy and weak strategic points, Raeder hoped to divide the forces of his stronger opponent enabling victory over each in turn (ibid). In the first month of the war, Raeder’s small surface and U-boat fleets accounted for 152,040 tons of allied shipping in the North Sea through minelaying and direct engagement (Churchill, W., 1948 p.342).

In the early morning of 14th of October, naval vessels in Scapa Flow became the target when German submarine U-47 succeeded in entering the Fleet anchorage. The ensuing loss of HMS Royal Oak whilst she lay at anchor emphasised just how poorly defended Scapa Flow was from seaborne attack.

© Source: Lindsay, G.J. & Dobney, K. (2014). Legacies of Conflict: Hoy & Walls Wartime Heritage Project, Wartime Development Document. Island of Hoy Development Trust.


BIRD, K.W., (1996). Eric Raeder: Admiral of the Third Reich. Annapolis: Naval Institute Press.

CHURCHILL, W.S., (1948). The Second World War. Volume 1: The Gathering Storm. London: Cassell & Co Ltd.

THE NATIONAL ARCHIVES OF THE UK (TNA), (1937-1946). ADM116/5790 Main Fleet Base – Scapa Flow: Inception, Development and History. Unpublished Archive Document.

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