The German Coastal Batteries and their ranges, May–June 1944

As part of the Atlantic Wall fortifications stretching all along the coast of northern Europe, the fortified city of Le Havre was the most heavily defended section of the D-Day landing beaches. Its geographical position guarded it from attack on three different sides, whilst simultaneously providing its batteries with a very wide range of attack. The Batterie La Corvée defended the city from the north using three 380mm guns taken from a French battleship, whilst many of the guns nearby were of Czech or French origin, which made ammunition supply more complex. Defences to the west were not quite as extensive as Le Havre. For example the Crisbecq battery, which was intended to be the main defensive position on the Cotentin Peninsula, only had two of three main casemates completed by D-Day. The general positioning of batteries along the Normandy coast covered all angles of attack with varied calibre artillery.