D-Day June 6, 1944 Two years of planning and preparation led up to the Allied Landings in Normandy on 6 June 1944 (pg. 3). British and American staffs had to work out every foreseeable detail for an undertaking that would involve the major military resources of the two Allied powers; immense stocks of shipping, aircraft, and supplies were assembled in the British Isles in an effort that taxed the war industries of both countries; before D-Day the Allied forces had carried out several months of bombing operations which were an integral part of the invasion itself. The first decisions were strategic, since the opening