e. The real war, argued Marshall, was to be a direct advance on Germany through France. Even as the "sideshows" proceeded, three other campaigns were under way -- the war against the German submarines, the US-British strategic bombing offensive against Germany, and the logistical buildup in Britain. The submarine conflict was a precondition for the bombing and the buildup. The Allies were fortunate that Hitler was had no interest in naval warfare. By 1943 the Allies had mastered the North Atlantic. The bombing offensive established control of the skies, which was another precondition for the invasion. The actual effect on German industrial production is still controversial, but there's no doubt that the bombing drained away German air resources that might have shown up over Normandy beaches in 1944. At the same time, the bombing forced the Germans to rationalize certain production techniques. The result, ironically, was the military production increased during the bombing offensive. British and American officers drew up plans for several contingencies in 1943. Operation OVERLORD was a large-scale assault against the German Army in France. This plan served as the basis for a final plan developed early in 1944 after General Eisenhower, designated as the supreme commander, arrived in Britain and established his command, Supreme Headquarters, Allied Expeditionary Force, or SHAEF. The overlooked question about D-Day is why it didn't happen in 1943. The Germans were greatly weakened after defeats at Stalingrad and North Africa in 1942. The French resistance was at its most effective. Instead, the British and Americans squabbled about how to proceed, and the delay meant that, in effect, nothing happened in 1943. It's one of the most interesting What If's of World War II. The over-all ground commander for the invasion was the former head of the British Eighth Army, General Montgomery, who also commanded the 21 Army Group, the controlling headqu...