The author considers the military thought of Major-General J.F.C. Fuller, a pioneer of tank warfare and one of the most important military thinkers of the 20th century. He explores Fuller’s formative experiences, showing how his early life, his service in the Boer War and in India, and his friendships with many alienated intellectuals, including the notorious Aleister Crowley, combined to shape his mental outlook and, eventually, his study of the phenomenon of war. Dr Reid traces the gradual evolution of his ideas about armoured warfare. He shows how Plan 1919 developed throughout the 1920s and, though not unflawed, proved to be a glimpse of the future of war. He discusses, too, Fuller’s maturing views on the theory and practice of war in the twentieth century. The author also considers Fuller’s controversial views on the principles of war, tactical doctrine and weapons technology.