Bodyguard of Lies is a 1975 non-fiction book written by Anthony Cave Brown, his first major historical work. Named for a wartime quote of Winston Churchill, it is a narrative account of Allied military deception operations during the Second World War. The British and American governments resisted Brown's attempts to research the book. Many of the topics were still classified and he was denied access to British war records. The material in the book is predominantly based on oral testimony as well as some American records, declassified toward the end of Brown's research.

Critical reception has been mixed, but generally negative. Contemporary historians, such as Charles B. MacDonald, praised the work – although some did comment on its length. Modern reviewers have identified inconsistencies or errors in the material, based on later declassified records. Also, some of Brown's personal conclusions have been questioned.

Bodyguard of Lies was Brown's first published book, following his career as a journalist in the United Kingdom and Australia.^[1] The work narrates Allied deception strategy on the Western Front for the years of 1943 and 1944. It particularly focuses on Operation Bodyguard; both the operation and the book's title were inspired by one of Winston Churchill's wartime epigrams; "In war-time, truth is so precious that she should always be attended by a bodyguard of lies."^[2]

Brown began researching and writing Bodyguard of Lies in 1961.^[3] Most of the material is based on oral testimony from Second World War intelligence personnel, as well as records from the National Archives and declassified American records (although Brown says that most of the book was written before he was able to access the latter, in 1974).^[3] Brown wrote Bodyguard of Lies at a time when details of both cryptography and deception during the war were still classified. His attempts at research was resisted by the British and American governments; he was denied access to British war records and had to undertake considerable work to obtain US records via Freedom of Information requests.^[1][4]