The Archaeology of Second World War U-boat Losses in the English Channel and its Impact on the Historical Record
This article examines how the archaeological record of 33 U-boats sunk in the English Channel during the Inshore Campaign, June 1944 to May 1945, compares with the assessment of U-boat destructions made by the Admiralty’s Anti U-boat Division (AUBD) in 1946. Comparison of the two shows an accuracy rate of 57 per cent across the entire Inshore Campaign, compared to ASD’s overall accuracy rate in the First World War of only 48 per cent. Crucially, the Inshore Campaign, when studied as two distinct phases (broadly 1944 and 1945) reveals the close relation- ship between accurate assessments of U-boats destroyed and detailed signals intelligence. It shows that, in 1944 in the English Channel, AUBD was 81 per cent correct in establishing where the U-boats were destroyed. This is for the main part down to the role Bletchley Park and the Secret Room played in decrypting U-boat radio signals, and the Operation Intelligence Centre (OIC) in co-ordinating the ASW effort during Operation Neptune. Such an accuracy rate represents total domination of the battlefield. By comparison, a lack of signals intelligence during 1945 caused by U-boat radio silence led to a drop in AUBD’s accuracy to only 36 per cent: even lower than the First World War. This shows the significant role signals intelligence played in tracking, hunting, and destroying U-boats, and being able to know when a sinking had occurred. The results show the crucial role ULTRA intelligence played during the key months of Operation Neptune and how it was used to target specific U-boats in transit to their operational areas.