How did Erwin Rommel strengthen German coastal defenses before the Normandy invasion?

To strengthen German coastal defenses before the Normandy invasion, Field Marshal Erwin Rommel implemented several strategic initiatives:

• Mine Laying: Rommel significantly increased the density of minefields along the coast, overseeing the placement of approximately four million additional mines on the beaches by June 5, 1944.1
• Beach Obstacles: He ordered the installation of various obstacles embedded in the sand below the high-tide mark, some of which were topped with mines.2
• Anti-Airborne Defenses: In areas susceptible to glider or parachute landings, he directed the placement of slanted poles, which troops nicknamed Rommelsspargel (Rommel’s asparagus).2
• Strategic Positioning: Drawing on his experience with Allied air superiority in North Africa, Rommel advocated for placing reserve forces immediately behind the coastal defenses to prevent the Allies from establishing a bridgehead. However, this strategy was hindered by disagreements with his superiors, including Gerd von Rundstedt, who preferred keeping reserves further inland.13