In 1943, Hitler ordered his forces to occupy the Italian mainland to protect the Third Reich's 'soft underbelly'. Although the Allied landings in Salerno in 1943 were successful, the Germans fought a series of hard, rearguard actions as the Allies slowly pushed north up the Apennines towards the Alps. These actions were based around the construction of a series of defensive lines: the Winter Line, the Gustav Line, the Hitler Line, the Caesar Line, the Gothic Line and the Voralpenstellung. This book explores the development and form of the six defensive lines constructed by the paramilitary Organisation Todt in Italy, examining the principles of defence of these key fortifications in visual depth, and discussing their fate in the wake of the Allied onslaught.