"A fascinating book, and the most detailed account you will find about intelligence operations during the Gettysburg campaign." —Dr. Vince Houghton, Historian/Curator, International Spy Museum, Washington, DC As intelligence experts have long asserted, "Information in regard to the enemy is the indispensable basis of all military plans." Despite the thousands of books and articles written about Gettysburg, Tom Ryan's groundbreaking Spies, Scouts, and Secrets in the Gettysburg Campaign is the first to offer a unique and incisive comparative study of intelligence operations during what many consider the war's decisive campaign. Based upon years of indefatigable research, the author evaluates how Gen. Robert E. Lee used intelligence resources, including cavalry, civilians, newspapers, and spies to gather information about Union activities during his invasion of the North in June and July 1863, and how this information guided Lee's decision-making. Simultaneously, Ryan explores the effectiveness of the Union Army of the Potomac's intelligence and counterintelligence operations. Both Maj. Gens. Joe Hooker and George G. Meade relied upon cavalry, the Signal Corps, and an intelligence staff known as the Bureau of Military Information that employed innovative concepts to gather, collate, and report vital information from a variety of sources.