Donald E. Markle holds a B.A. in History from the University of Maryland and did graduate work at both American and George Washington Universities. He has lectured at the Smithsonian Institute, the National Archives, and Ford's Theater in Washington. His previous works include Pennsylvania: An Illustrated History, Spies and Spymasters of the Civil War and Intelligence Was My Line: Inside Eisenhower's Other Command, all published by Hippocrene Books. He resides in Gettysburg, Pennsylvania.