With invasion a very real threat, in 1940 Great Britain began a huge military construction programme designed to stop an invading army in its tracks. Around vulnerable coastlines, and inland, thousands of pillboxes, anti-tank barriers and other obstacles were erected to defend against attacks from sea and sky. Though many of these structures were dismantled in the wake of the Second World War, the coast and even some inland areas still boast a wealth of fascinating remains; in this fully illustrated introduction, fortifications authority Bernard Lowry guides the inquiring reader in identifying these remaining defensive structures and explains their seemingly 'random' placement across the British landscape.