Book excerpt: Defending Albion is the first published study of Britain's response to the threat of invasion from across the North Sea in the first two decades of the Twentieth Century. It examines the emergency schemes designed to confront an enemy landing and the problems associated with raising and maintaining the often derided Territorial Force. It also explores the long-neglected military and political difficulties posed by the spontaneous and largely unwanted appearance of the 'Dad's Army' of the Great War, the Volunteer Force.