The Ultra Secret and Churchill's War Memoirs

Ultra was one of the best-kept secrets of World War Two, concealed for nearly 30 years. A major reason, this article argues, was the precedent set by Churchill's war memoirs, published in 1948–54. The intelligence authorities feared that, if Churchill disclosed anything about Ultra, this would be a green light to those who had worked at Bletchley Park. Using documentation from the Churchill Archives and the Cabinet Office files, the article examines the pressure they successfully put on Churchill and the way Ultra was edited out of his memoirs, looking particularly at big stories such as the battle for Crete, operation Barbarossa, Pearl Harbor and the D-Day deception campaign.