Alarmed by the raids on St Nazaire and Dieppe in 1942, Hitler had ordered the construction of fortifications all along the Atlantic coast, from Spain to Norway, to protect against an expected Allied invasion. He envisioned 15,000 emplacements manned by 300,000 troops, but shortages, particularly of concrete and manpower, meant that most of the strongpoints were never built. As it was expected to be the site of the invasion, the Pas de Calais was heavily defended. In the Normandy area, the best fortifications were concentrated at the port facilities at Cherbourg and Saint-Malo. Rommel was assigned to oversee the construction of further fortifications along the expected invasion front, which stretched from the Netherlands to Cherbourg, and was given command of the newly re-formed Army Group B, which included the 7th Army, the 15th Army, and the forces guarding the Netherlands. Reserves for this group included the 2nd, 21st, and 116th Panzer divisions.