Review of The Secret Life of an American Codebreaker: Codebreaker Girls by Jan Slimming

In 2021 Codebreaker Girls: A Secret Life at Bletchley Park, Jan Slimming’s first book about World War II codebreaking appeared. Slimming’s interest in codebreaking and, in particular, in Bletchley Park resulted from the fact that her mother Daisy Lawrence had served as a civilian codebreaker at Bletchley Park. What Slimming discovered of her mother’s service as a codebreaker is told in her first book. The first book also includes a bit of the story of her father Stanley Moore, who joined the Royal Army Service Corps, was taken prisoner by the Japanese during the fall of Singapore in 1942, and was a POW during the remainder of the war. Unfortunately Slimming tried to expand the story of her mother to include much of the cryptologic history of World War II, and in trying to do so she went badly wrong. Codebreaker Girls: A Secret Life at Bletchley Park is filled with errors and misunderstandings (Christensen 2022). This new Codebreaker Girls book is built upon the story of Janice Martin Benario, a US Navy codebreaker during World War II. Readers would be forgiven if, part way through Secret Life, they lose track of what would appear to be the focus of the book – the story of Janice Benario – because, like her first book, Slimming has attempted to go beyond the foundation of the book and tell a larger story – in this case seemingly the complete story of World War II codebreaking and more. Slimming has also filled this book with errors and misunderstandings. As with the review of A Secret Life at Bletchley Park, it unfortunately becomes necessary to provide evidence of Slimming’s errors and misunderstandings. Page ix: Problems begin with the second paragraph of the “Prologue.” Slimming locates the building that is designated Main Navy on Pennsylvania Avenue in Washington, DC. Main Navy was located on B Street, which is now Constitution Avenue. This might seem like a minor error, but such errors pop up throughout the book. Page 38: Referring to a delay in the receiving of a 6 December 1941 diplomatic message from President Roosevelt to the Japanese Emperor, Slimming explains that because the message was encoded with the less secure US diplomatic GRAY code US Ambassador to Japan Joseph Grew thought that it was possible that “Japanese militants had intercepted the message, solved its contents and deliberately delayed it to hinder any peace effort.” (37–38) Slimming then, referencing David Kahn’s The Codebreakers page 495, says: “The real reason, however, was not the code or the diplomats but a full embargo placed on all Japanese military incoming diplomatic messages.” (38) Much of what Slimming says about this event seems to be based on Kahn’s explanation. (Kahn