Even before the fall of France in May 1940, the United States was slipping away from the dubious neutrality that it had proclaimed at the start of the European war. President Franklin D. Roosevelt declared a national emergency and ordered the Navy into the Atlantic, ostensibly on “neutrality patrols,” but in fact to help the British by convoying ships at least part of the way across the danger zone. Against the possibility that the United States would eventually enter the war, American naval and military staffs began a series of unofficial, unrecognized, but nonetheless crucial discussions in Washington between January and March 1941. The most important single decision the military leaders reached in these American—British Conventions, or ABC talks for short, was that Germany would be the number one enemy of any future Anglo-American partnership. Such a decision was contrary to long-standing assumptions of Army and Navy war planning. Plan Orange, meticulously refined over more than two decades, outlined the strategy to be employed when the United States and Japan eventually went to war, as many naval and military officers assumed would eventually happen. Tension in the Pacific increased throughout 1941, and thoughtful observers of the Far East warned of Japanese aggressive designs that would almost certainly involve American interests and possessions. Despite this, American leaders agreed that any war that might begin with Japan would have to take second place; primacy of effort would go to defeating Germany.
Much of this reflected President Roosevelts conviction that the fate of the United States was indissolubly linked with that of the United Kingdom. The continued existence of the latter was in the best interests of the United States, not only because of the commonality of language and culture, but also because Britain stood as a bulwark against any possible Axis aggression in the Americas. American armed forces in 1941 were frankly unready for global war, and it was the British fleet, guaranteeing control of the Atlantic, that provided security during the period of national mobilization that the President was attempting to hurry. The President and his principal advisors were likewise convinced that the United States should do that which was morally right, rather than just that which was politically expedient. The conclusion Roosevelt drew was that American energies should be focused in support of the British to defeat the greatest threat to the free world. That threat, he concluded, was Germany. Prime Minister Winston Churchills delight with the agreement, however, was soon to be tempered by the American view on how it should be carried out. American plans for the impending war were conditioned by an interplay of military philosophy and economic and geographic constraints that did not affect the United Kingdom.
One aspect of European military thought that had fallen on fertile ground in the United States came from one of the most profound military thinkers of the century, Maj. Gen. J. E C. Fuller, a highly experienced British officer whom many regarded as the foremost exponent in the world of armored warfare. Fuller’s enumeration of the “principles of war” appealed greatly to Americans. A listing of the most important considerations in military operations naturally appealed to the mechanically-minded. Yet the principles of war were more than just a check-list for military commanders. They were, rather, an organized way of thinking about war, and most officers saw the “principle of the objective” as far and away the most important of all considerations. Their military ideal was a legacy of the American Civil War and the style of Gen. U. S. Grant, who tenaciously maintained contact with Gen. R. E. Lee’s Army of Northern Virginia until he achieved victory. Americans preferred a short, extremely violent war, with all possible resources brought to bear in continuous combat until the enemy was defeated. The principle of attacking a clearly defined and attainable military objective, almost always the main body of the enemy’s army, accorded well with the limitations under which American officers perceived they would have to fight.
Geography was equally important. Broad oceans offered the Americas great physical security from attack, but they also isolated the continent from European and Asiatic battlefields. In the event of war, as planners at the Army War College clearly foresaw during the 1920s and 1930s, the United States would have to erect and maintain a large and sophisticated logistical structure to send substantial forces across the oceans, sustain them in foreign theaters, and employ them against powerful enemies on other continents. If war came in Asia as well as in Europe, as some officers expected, the problem of allocating scarce resources would be even more acute. Those essential demands on manpower and materiel would certainly detract from the total fighting power the United States could muster. These geopolitical factors were expressed in the American planning document for World War II.
In the spring and summer of 1941, during the last months of peace for the United States, the War Department was superintending the sale of surplus war materiel to Britain and other nations arrayed against Hitler, and considering how to meet the demands imposed by the recently passed Lend-Lease Bill, under the terms of which the United States would transfer massive amounts of military equipment to the countries fighting the Axis. At the same time, the Army was involved in a limited expansion, virtually a peace-time mobilization, that threw mobilization plans out of joint. In the work of military supply and procurement, chaos reigned. In an attempt to develop a manageable production plan, the Assistant Secretary of War and President Roosevelt asked the general staff for an estimate of what would be needed to defeat the Axis if the United States became involved in the war.
Gen. George C. Marshall, Army Chief of Staff, handed that question to Albert C. Wedemeyer, an infantry major assigned to the War Plans Division of the general staff, and Wedemeyer’s staff estimate, later known as the Victory Plan, succinctly delineated the steps necessary to win a European war. Wedemeyer reasoned that he could not estimate the nations total military production requirements unless he had some idea of the size and missions of the Army in the event of war. He immediately drew on the substance of the ABC talks to define the Army’s mission in the event of war. The chief task, he assumed, was the defeat of Germany, to which all other missions would be subordinate.
Military logic, as embodied in the principles of war, demanded that the Army stricdy keep its eye on the objective, and not fritter its limited energies away in attractive, but indecisive, side issues. If the defeat of Germany was the objective, then the mission was to attack the heart of German power as early and as forcefully as possible. That meant massing the Army for a direct invasion of the continent of Europe at the earliest possible date. Determining that date relied on three interrelated factors: the date by which enough men could be trained and equipped for war, the date by which the necessary shipping would be available to move them to Europe and sustain them there, and the date by which the necessary military preconditions for attack could be completed.
Careful consideration of Army mobilization and training, military construction, and naval and merchant shipbuilding revealed that the Army could expect to go over to the offensive no earlier than July 1, 1943. Achieving the necessary military conditions for attack, though simple to state, was a more uncertain proposition. Wedemeyer suggested in his plan that no invasion of Europe could succeed until the navies defeated the Axis fleets and secured the Atlantic lines of communication; the Allies established air superiority over Europe; air bombardment had disrupted the German economy and industry, thus decreasing that country’s war-making potential; German military forces had been weakened; and adequate bases had been established. Although he did not specify it in the Victory Plan, Wedemeyer assumed, and fellow war-planners explicitly stated, that the only useful European bases that would still be available to the United States in 1943 would be those situated in the British Isles.
Thus, before war even began for the United States, there existed a conceptual plan for the ultimate defeat of Germany. That plan relied on an invasion of the continent of Europe to strike into the heart of Germany, to the exclusion of all other military designs. Implicit in the plan were fighting and winning the Battle of the Atlantic; what became known as the combined bomber offensive that sought to destroy German industry and economic life; continued attacks on the Germans wherever they could be found, to decrease their military strength; and the creation of a major American buildup in Britain. The climactic battle, because of the practicalities of production and military preparations, could not start before July 1943, two years hence.
American war planners accordingly had to figure on deploying a large army and air force, as well as a powerful navy, to Europe; sustaining it there while maintaining long and easily attacked lines of communications across the oceans; allotting enough military power at least to contain the Japanese in the meantime; and producing enough materiel to support not only American forces, but also the armies of the Allies. This, they felt, could never be done without a master plan, adjustable in fine detail, but not in its major points. Such massive industrial production demanded careful timing, and Americans wanted a corresponding military timetable.
The choice of Britain as a base for the attack on Europe, made while Eisenhower was chief of War Plans Division in early 1942, was equally crucial. Early, planners dismissed fanciful ideas of landings in Liberia and subsequent campaigns through North Africa, across the Mediterranean, and into southern Europe. A concept to deliver American troops to Russia was scrapped because shipping routes to Murmansk or through the Persian Gulf, both for troops and for supplies, were simply too long. Attacks through Portugal, Norway, and Spain were all dismissed as too roundabout.
For a time, there was serious thought about an attack from the Mediterranean, where the British were already doing well against German forces. Despite Prime Minister Winston Churchill’s later enthusiasm for the “soft underbelly” of Europe, Americans rejected the Mediterranean avenue of approach because long supply lines made it impossible to concentrate full Allied strength there, and because of the distance to the heart of Germany from North American bases when the attack had to pass through southern Europe. More serious opposition to an attack through the south of France, or through the Balkans, arose because of the extremely difficult terrain, favorable for defense, that stood between the Mediterranean shores and Germany.
The choice settled on Britain for all the reasons that made the other options impractical. The most important single consideration was that Britain lay on the shortest of all possible transatlantic routes from the United States. A perennial problem for war planners, regardless of the proposed operation, was the perpetual Allied shortage of merchant ships. The Battle of the Atlantic had consumed too many ships, both merchant and naval; losses that were made up by new construction at the cost of accumulating the tonnage needed to increase the pace of offensive operations. Many convoys had to be dedicated to feeding and supplying the British Isles, while others tried to sustain the Soviet ally, whose continued resistance was an essential element in all American war planning. Once war began, other vessels had to be diverted to maintain American and Commonwealth military strength in the Pacific, even at minimal levels. Economy of supply was therefore a foremost consideration. A short route meant a shorter travel time. An easy route facilitated large convoys. Good ports in Britain meant a shorter turnaround time for the ships. Placing the American buildup in the British Isles was the most efficient use of scarce shipping.
Secondly, the British Isles were a logical point of departure for military operations against the continent. Big enough to support the buildup, the islands were also the best place from which to use relatively short-ranged fighters of the Royal Air Force to support the landings, and an unsink-able aircraft carrier for the American Army Air Forces. The short distance across the English Channel offered for the Allies the chance to give the attacking infantry continuous and effective air support. The Royal Navy, major units of which were already concentrated around the North Sea to bottle up the German surface fleet, could most easily be used to support landings against the Channel coast. The most important, however, was the geographical fact that the most direct route into the center of Germany was the one from the French coast opposite England, and thence across northwest Europe. That route also offered the minimum in natural, and therefore defensible, obstacles. Militarily, it was the most logical choice.
For the Americans, the decision to use the United Kingdom was axiomatic. When compared with the other possible avenues of approach, it was superior in almost every way, offering the possibility of the quickest buildup and concentration of force. The intention to concentrate rapidly in Britain meant that the United States would enforce rigorous economies of manpower and materiel in the other theaters, while intensifying the campaign of aerial attack on Germany and blockade of Europe, and the naval war in the Atlantic. Industrial mobilization plans began to structure American industry to support such a plan, and the military enthusiastically began to organize itself around the requirements for just such a major attack. American planning for what became Operation Overlord actually began before the United States entered the war, and it was always the essence of American war policy. Literally everything the United States did was aimed at that decisive invasion of the continent, and military operations were judged in terms of how well they contributed to that end. Over-lordyN2& far more than just D-Day, and far more than just one important battle. It was the culmination of the entire American strategy.