A Force explores an area of World War II deception history that has often been neglected. While older studies have focused on the D-day deception campaign and Britain's infamous double-agents, this work explores the origins of Britain's deception activities to reveal how the British became such masterful deceivers. This is the first work to focus exclusively on A Force and the origins of British deception, examining how and why the British first employed deception in World War II. More specifically, it traces the development of the A Force organisation, first formed in Cairo in 1941, as the first British organisation to practice both tactical and strategic deception in the field.