"Intelligence Investigations: How Ultra Changed History" is a textbook published by Routledge in 1996 as part of the Studies in Intelligence Ser. Authored by Ralph F. Bennett, the book delves into the historical and political implications of intelligence investigations during World War II, with a focus on the role of the Ultra codebreaking effort. The UK-B Format Paperback is 216 pages long and written in English, making it a valuable resource for students and scholars interested in military history, political science, and national security.