The German coastal defences in northern France were part of the so-called 'Atlantic Wall'. This included minefields, beach obstacles and heavy guns, with infantry divisions covering them. Behind the coast were the German Army's mobile reserves, which comprised the best available troops and equipment, and these forces posed the greatest threat to the Allies. At sea and in the air, the Germans were much weaker. This document is from a survey of the effects of bombing on the coastal defences and shows a German gun emplacement.