Daniel Whittingham presents the first full-length study of one of Britain's most important military thinkers, Major-General Sir Charles E. Callwell (1859-1928). It tells the story of his life, which included service in military intelligence, the South African War, and on the General Staff before and during the First World War. It also presents the first comprehensive analysis of his writing: from his well-known books Small Wars (1896) and Military Operations and Maritime Preponderance (1905), to a host of other books and articles that are presented here for the first time. Through a study of Callwell's life and works, this book offers a new perspective on the nature and study of military history, the character of British strategy, and on the army to which he belonged.