Book excerpt: Written by the undisputed dean of U.S. denial and deception experts, Practise to Deceive is the most in-depth look at deception as a military strategy. Barton Whaley knew the history of denial and deception across time, disciplines, and culture. He was the foremost authority on the intricacies of denial and deception strategy and tactics. For Whaley, deception was a mind-game, requiring imagination, deep critical thought, a profound understanding of the enemy as well as one's self (a variation of Sun Tzu), and patience and fortitude. This book presents 88 vividly descriptive case studies to serve as a handbook for intelligence and military professionals. In Whaley's analysis, variations in guilefulness between opposing individuals or groups can be crucial in deciding who achieves victory in combat.