Sir William Milbourne James (1881–1973) was a British Naval commander and author who played a key role in the work of the Naval Intelligence Division during the First World War. In this book, which was first published in 1948, James presents a concise discussion regarding the role of naval power in the history of Britain. The text was derived from the Lees Knowles Lectures for 1947, which were delivered by James at Trinity College, Cambridge. This book will be of value to anyone with an interest in perspectives on British military history.