Generalfeldmarshall Erwin Rommel inspecting beach defences. Behind him stands Dr Wilhelm Meise, Chief of Engineers. The crude concrete and steel device Rommel is scrutinising is designed to sit below the sea level and rip open the hulls of landing craft as they pass overhead. In the event, the Allies timed the Invasion so that most such defences would be exposed by the tide and the craft could steer safely around them.