Arctic Convoys: Bletchley Park and the War for the Seas
336 pages
RAdm (Retd) Peter Sparkes
This fascinating and meticulously researched book recounts the Admiralty’s reliance upon Bletchley Park’s Enigma during the Arctic Convoy Campaign (1941-45). During those four bitter years, convoys delivered more than 800 shiploads, or 4 million tons of materiel and supplies to the Soviet Union, battling tumultuous seas, extreme cold, and under near constant threat of attack from German air, surface and sub-surface units. The war at sea was finally balanced throughout, operational advantage was hard won, both at sea and in the home base. It was the Government Code and Cypher School, at Bletchley Park, that gave Britain and her allies a vital, competitive edge.
The popular perception is that U-boats were the greatest threat to the Arctic convoys. It is true that more ships (41) were lost to submarines than by any other cause, but they accounted for fewer than 50% of the total merchant ships lost. A poor return for the hundred or so U-boats Admiral Doenitz reluctantly deployed to the Arctic – one allied ship sunk for every two submarines committed. In reply, circa 40 U-boats were lost, broadly one for each merchant vessel sunk – an unsustainable attrition rate for the U-bootwaffe. A further 37 ships were lost to Luftwaffe air attack during the long boreal summer days, with aircraft flying from northern Norwegian bases such as Bardufoss, specially constructed for the purpose of striking allied convoys. The Kriegsmarine’s much vaunted surface action groups, based around Tirpitz and Scharnhorst, served as a more effective Fleet in Being than a striking force, tying down the Home Fleet, yet sinking only three merchant vessels, the cruisers Edinburgh and Trinidad, the destroyer Achates and the minesweeper Bramble.
Bletchley’s insight enabled the Admiralty to re-route convoys to avoid the patrolling wolf-packs, schedule them to avoid the Tirpitz, Scharnhorst and their escorts, and to give indicators and warning of impending Luftwaffe sorties. Traffic analysis, signal interception (SIGINT) by the Y network, afloat and ashore, enabled cryptologic success in Hut 8 and latterly A and B Block – combined, their insight correlates closely to allied naval success. SIGINT ‘blackouts’ in contrast portended significant allied loss at sea. The author’s step by step analysis of Admiral Sir Dudley Pound’s ill-feted decision to ‘Scatter’ PQ17 is particularly enlightening. When coupled with reconnaissance and other sources of intelligence, including the discrete support provided by the Swedish Intelligence services, that intercepted German landline communications, the Home Fleet was often afforded vital operational advantage. David Kenyon capably tells of this dependency in a way I have not read before. It is compelling.
Three hundred thousand tons of shipping (around 7.5%), 829 merchant sailors, and 1,840 Royal Navy personnel were lost on passage to and from Murmansk. It could have been so much more, had it not been for the secret army that doggedly prosecuted the enciphered Enigma codes behind the wire in the seemingly innocuous environs of Bletchley Park camp. The Kriegsmarine lost nearly 5,000 men during the campaign. Writing in 1961, in his definitive history of the ‘War at Sea’, Roskill was unable to reference the decisive impact that SIGINT and ULTRA had had during the Second World War, even though he himself had been privy to it. Like many of those party to the enormous access it afforded the allies, Roskill never spoke of it, even after the secret’s controversial disclosure in 1976. I have been very fortunate to visit Bletchley Park and seen some of the few remaining artefacts that survived the post war sanitisation effort. It is an impressive museum; I recommend it strongly to those who have not yet been there. If you do visit, I would also advise that you buy a copy of David Kenyon’s Arctic Convoys: Bletchley Park and The War for the Seas from the gift shop, it will absolutely bring the story to life.
