Based upon research in numerous archival sources, including the personal papers of the major British military and political leaders of the day, this is a study of British military planning during a period in which long-successful defence and military strategies had to be reappraised in light of new technological advances. Britain emerged victorious in 1814 after 22 years of war with revolutionary and Napoleonic France. However various technical and international developments - particularly the invention of the steam engine - gravely undermined Britain's security between 1814 and 1870. Because steam power enabled ships to manoeuvre independently of wind and tide, Britain was now vulnerable to attack from all sides, forcing her to devise new defensive strategies to repel invasion. Partridge examines Britain's response to the advent of steam power as well as the special military defence problems faced by the country as a result of its geographical position and contemporary political realities. Partridge offers an overview of Britain's strategic position in the years following the war wth France. Subsequent chapters examine each aspect of the country's military planning in detail, beginning with an exploration of the decline of the Royal Navy. Partridge then addresses the internal machinery of defence planning, the political constraints placed upon defence planners, the effects of popular aversion to a standing army and the new awareness of Britain's strategic vulnerability. Individual chapters are devoted to the three major prongs of Britain's land defences: the regular army, fortifications and the militia, yeomanry and volunteers. This study offers new insights into Britain's ability to adapt to the new military and technological realities of the early 19th century.