Artillery position, part of the Atlantic Wall (Photo: Bundesarchiv, Bild 101I-263-1583-35 / Valtingojer / CC-BY-SA)

      Hitler knew an invasion would at some point materialize. On 23 March 1942, in his Führer Directive No. 40, he declared, ‘In the days to come the coasts of Europe will be seriously exposed to the danger of enemy landings.’ Appointing 66-year-old Field Marshal Karl Gerd von Rundstedt in command, he ordered the building of a defensive perimeter known as the Atlantic Wall. Employing 2 million labourers from across Nazi-controlled Europe, many of them slave workers, construction began on a line of fortifications that, once completed, spread 2,800 miles along the coast of the whole of Western Europe – from the northern tip of Norway, along the coasts of Denmark, Germany, the Netherlands and Belgium, along France’s Channel and Atlantic coasts down to the border of neutral Spain in the south. Consisting of some 700 concrete gun batteries and 12,250 fortified bunkers at intervals rarely more than a hundred yards, it was guarded round-the-clock by 300,000 troops. These troops were far from Hitler’s crack troops, but were, instead, often made up of the oldest and youngest men and POWs captured on the Eastern Front and forced into working for the Germans.

      In February 1944, Hitler appointed one of his ablest generals, Erwin Rommel, to oversee the defence of France. Rommel, who had gained fame during Germany’s defeat of France four years earlier and in North Africa where he earned the sobriquet ‘the Desert Fox’, believed that to prevent the Allies from securing a presence on continental Europe, they had to be contained on the beaches and driven back to the sea within ‘the first twenty-four hours’. Declaring the French section of the Atlantic Wall to be inadequate, Rommel ordered the immediate bolstering of defences, with the laying of mines both on the beaches, in places up to a thousand mines deep, and inland, eventually numbering some 6 million, and the installation of obstacles underwater, such as lethal metal spikes. In April 1944, on Rommel’s orders, the Germans planted huge numbers of wooden poles, fourteen to sixteen feet long, sticking out of the ground in fields behind the beaches to disrupt and damage potential Allied paratroopers or gliders. The poles, nicknamed ‘Rommel’s asparagus’, were linked by wire and often armed with a mine.

      Rommel also wished to have all nine German panzer divisions available in northern France near the beaches to help repulse any invasion. His superior, Rundstedt, wanted the tanks positioned north of Paris, out of reach of Allied firepower, from where they could be moved as required at short notice. Rommel argued that Allied air superiority would simply destroy the panzers once they tried to move into position. Refereeing this battle of wills, Hitler compromised and allocated three divisions to Rommel, and the rest to Rundstedt.