The Allied invasion of Italy in September 1943 removed Rundstedt's fears that France would be invaded that summer, but he could not have doubted that the massive build-up of American troops in Britain meant that a cross-channel invasion would come in 1944. In October Rundstedt sent Hitler a memorandum on the defensive preparations. He placed no faith in the Atlantic Wall, seeing it merely as useful propaganda. He said: "We Germans, do not indulge in the tired Maginot spirit." He argued that an invasion could only be defeated by a defence in depth, with armoured reserves positioned well inland so that they could be deployed to wherever the invasion came, and launch counter-offensives to drive the invaders back. There were several problems with this, particularly the lack of fuel for rapid movements of armour, the Allied air superiority which enabled them to disrupt the transport system, and the increasingly effective sabotage efforts of the French resistance. Hitler was not persuaded: his view was that the invasion must be defeated on the beaches. Characteristically, however, he told Rundstedt he agreed with him, then sent Field Marshal Erwin Rommel to France with orders to hasten the completion of the Atlantic Wall; while Rundstedt remained the commander in France, Rommel became the official commander of Army Group B. Rundstedt was extremely angered by this decision; although he admired Rommel's tactical skill, he knew from his colleagues that Rommel was notoriously difficult to work with and would mostly be able to ignore Rundstedt's authority thanks to his patronage by Hitler and Goebbels. Rommel in fact agreed with Rundstedt that the Atlantic Wall was a "gigantic bluff", but he also believed that Allied air power made Rundstedt's proposed defense plan impossible.