Department of State Atomic Energy Files2

Memorandum by the Commanding General, Manhattan Engineer District (Groves)3


Our Army of the Future—As Influenced by Atomic Weapons.

In planning for our Army of the future, two distinct situations with respect to atomic weapons should be given consideration.

First Assumption: That satisfactory world agreements with respect to atomic energy have been made which ensure that atomic bombs will not be used under any circumstances.

Such agreements must provide for complete information at all times as to the activities of all nations in the atomic field. To get that information, it will be essential that our representatives have the right to travel freely anywhere, at any time, to observe and raise questions about any activity which they may suspect is related to the use of atomic energy.

This means the abandonment of all rights of privacy—that of the home, the laboratory and the industrial plant throughout the world including the United States.

Should such agreements be accompanied by the destruction of our present supply of atomic weapons and by measures which would prevent [Page 1198] manufacture of additional ones, then our Army of the future would not be influenced greatly by the non-existent atomic weapons until the agreement was broken or threatened. If the agreement were broken, the world would head directly into an atomic weapons armament race with the assurance of supremacy if she chose to assume it for the nation winning that race. Unless the United Nations Organization achieves an unprecedented success in establishing genuine world government and a reduction of national ambitions and suspicions—in other words, unless the UNO genuinely abolishes all chance of major wars—this eventuality will be most probable.

If the world agreement provided for the retention of a small number of atomic weapons for the purpose of enforcing peace,

by some international agency,
by the United States as the trustee agency of that organization, or
by each of the major powers as agents of that organization,

our Army of the future must be planned with due regard for the unprecedented power of the weapon and its potentiality for sudden, crippling delivery. A small number of such bombs could give an enormous initial advantage but would not ensure final victory unless they were followed up by more bombs.

Second Assumption: That satisfactory world agreements have not been reached and atomic bombs will be available to each of the three major nations within the course of 15 or 20 years or even 5 or 10.

Should there be an armament race in atomic weapons,—and the world could not long survive such a race—then the United States must for all time maintain absolute supremacy in atomic weapons, including number, size and power, efficiency, means for immediate offensive use and defense against atomic attack. We must also have a worldwide intelligence service which will keep us at all times completely informed of any activities of other nations in the atomic field and of their military intentions.

If we were truly realistic instead of idealistic, as we appear to be, we would not permit any foreign power with which we are not firmly allied, and in which we do not have absolute confidence to make or possess atomic weapons. If such a country started to make atomic weapons we would destroy its capacity to make them before it had progressed far enough to threaten us. If there was only some way to make America sense now its true peril some 15 to 20 years hence in a world of unrestricted atomic bombs, the nation would rise up and demand one of the two alternatives essential to its very existence. Either we must have a hard-boiled, realistic, enforceable, world-agreement ensuring the outlawing of atomic weapons or we and our dependable allies must have an exclusive supremacy in the field, which [Page 1199] means that no other nation can be permitted to have atomic weapons. The United States is in a position now to get and enforce one of those alternates—five years from now will be too late to initiate the agreements. Genuine and proven mutual confidence between the great nations is the prime essential requirement for the agreement.

The atomic bomb is not an all-purpose weapon. One would not use a pile-driver for driving tacks when a tack hammer would do a better and a cheaper job. It is a weapon of tremendous, devastating power, capable of being produced in more than adequate numbers to influence decisively the outcome of any future conflict. It can be simplified and improved from its early models and if we are to judge from past developments of other weapons future bombs should be more powerful than the bombs used at Hiroshima and Nagasaki.

The atomic bomb is exclusively an offensive weapon—a weapon of rapid attrition. With it war can be carried to the enemy’s heart and vitals and there it can utterly destroy his capacity to fight and even to live. If used in sufficient numbers, it can completely destroy the densely populated centers of any nation on earth. It is a weapon of suddenness, completeness and totality. Two disciplined nations each using the bomb can destroy each other’s entire national life, yet neither could invade the other with large armed forces in the face of atomic bombs used on the convoys, beachheads or airheads. It thus makes war unendurable. Its very existence should make war unthinkable.

The atomic bomb cannot stand alone in the nation’s arsenal. To put all our reliance on that one powerful weapon is to court disaster. It could be captured or sabotaged. One or more might prove to be “duds” at the wrong time. The bomb must be transported safely to bases from which it can be sent against any enemy. These bases must be held safe against the enemy and new bases closer to the enemy may need to be won. The bomb must be delivered on enemy targets in spite of enemy resistance. The territory attacked must be occupied and controlled. For our protection the air and sea lanes around our lands and toward any enemy must be dominated by our arms and adequate forces, air and ground and possibly sea, must be used for the defense of our large centers of population and industry. All these considerations mean that we must have adequate, diversified, well-rounded military forces, trained for almost instantaneous action. Furthermore the entire nation must be disciplined to withstand cataclysmic destruction of key cities at home and still be able to win the war.

The size of an Army mobilized for a war would be. materially smaller than that for the recent war, because it is inconceivable that a war carried on with an ample supply of atomic weapons on one or both sides could last long enough to mobilize, train, equip and maintain [Page 1200] a vast Army. The force mobilized at the start of a war could perhaps be doubled or trebled in time to be useful.

For the next 5 to 10 years, our Army will have the major tasks of occupying former enemy territory, garrisoning overseas bases, carrying on a large military training program and executing the administrative, supply and overhead functions for the Army. For those tasks there will necessarily be required a large force, both ground and air, without considering the effects of atomic weapons. The size, composition, organization and equipment of the forces concerned with the essential tasks mentioned above will be such as will best meet the changing mission over the next several years.

The mobile forces of the Army outside those mentioned in the preceding paragraph will be definitely and markedly affected by the impact of the atomic bomb. Just how and to what extent is not yet clear. It will be largely influenced by what effective measures, if any, are taken to control the atomic problem. For the next several years study, experiment, invention, development and training will point the way toward the best kind of an Army to build around the all-powerful atomic weapons. One would be rash indeed to try and state now in detail what that Army will be ten years hence. Certain indications are clear, however, and preliminary conclusions can be drawn from them. Some of those follow:

Should we engage in a major war within the next five years, the atomic bombs used will be much like those used at Hiroshima and Nagasaki. Delivery of the bombs probably will be made by airplanes with selected crews. Assembly and technical supervision of the bombs will be done by scientific and technical personnel from the Manhattan project. The bombs are still a long way from being standard or routine weapons. What will come in the future depends on the development of new weapons and methods of delivery.
Special air units, with most modern aircraft and other equipment, trained for instant attack, located at bases primarily in the United States will have to be assigned the mission of delivering atomic bombs any where in the world.
There should be several highly mobile ground units, trained and equipped for rapid movement by fastest transportation for the purpose of seizing and holding bases and critical areas. Those mobile units should be backed up by a number of slower-moving, more heavily armed units to act in support.
There should be available as mobilized units or available for instant mobilization, sufficient forces (land, sea and air) to control the sea and air lanes surrounding the United States and its possessions and for safe distances beyond so as to protect our cities and industries.
Overseas bases needed for launching attacks against potential enemies should be adequately equipped, guarded and supplied.
All possible methods of delivery of atomic weapons including aircraft, guided missiles, rockets and submarines should be studied and developed. Units for using best methods of delivery should be made part of our armed forces.
Our intelligence forces must be strengthened many-fold, made world-wide and be competent to always know and to give prompt, accurate and complete answers to the question: “What are other nations doing in the atomic weapon field”?
Many governmental and military installations must be arranged by construction, concealment, dispersal and other means so as to continue to function during an enemy attack with atomic weapons. Our atomic weapons installations, including certain manufacturing plants, storage points, launching sites and airbases, would be in that category. General dispersal of industry does not appear feasible because of the dislocations involved. If dispersal of key critical industries is undertaken, it should be for self-contained plants and not just the component parts. An atomic weapon war is visualized as one of short duration; hence it is believed that the war will have to be fought largely with our initial stockpile of weapons and equipment, augmented by all-out production of essential items.
Forces of 8 to 10 million men in the Army for a war are not now visualized, for the reason that an atomic weapon war should have reached a decision before such great forces could be mobilized, equipped, trained and maintained. Forces of perhaps one-third that number might be required and their assembly in time seems feasible. However since atomic war will be truly a war for survival, our total manpower should have had military training and be disciplined to withstand the tremendous shock of atomic attack.
Because an atomic weapon war will not let us have months to prepare in comparative security, a larger percentage of our war force unit must be kept always ready. Much of that force should be in components, including air, which can be ready to carry immediate offensive war against the enemy. With atomic weapons, a nation must be ready to strike the first blow if needed. The first blow or series of first blows may be the last.
Elaborate, fixed coast defenses in their present type will lose their importance. Some of the present installations should be retained and manned to protect our most important harbors and naval anchorages against sudden forays from the sea.
Defense against the atomic bomb will always be inadequate. The only defense which we can yet foresee is to stop the carrying vehicle. So long as the bomb is carried by aircraft, it will be possible to stop a large percentage of those aircraft attacking our vital centers but only one or two need get through to wreak great destruction. Our defenses against atomic attack by air will therefore require considerable [Page 1202] forces. There must, nevertheless, be continued research of the highest quality and urgency in the defensive field.
While this subject is not in my field of responsibility, it is clear that a strong properly equipped Navy to ensure our freedom of the seas is an essential part of our national defense. The Navy is taking full advantage of all the lessons which can be learned from studies of atomic weapons including the data which will be available after the forthcoming tests against naval vessels.
Detailed plans concerning size, organization, composition, and equipment of the Army to utilize effectively atomic weapons are now under intensive study. As these plans crystallize such of them as require Congressional action will be presented promptly for consideration by the Congress.

The atomic bombs dropped on Japan had two primary effects: first, the sudden and unexpected ending of the war with the consequent saving of the lives of thousands of our men; and second, a complete revolution in future military thought. The atomic bomb is a terrifying advance over other weapons. It will influence warfare more than did gunpowder or the airplane. Its destructiveness makes it imperative that world peace be achieved. If the peoples of the major powers of the world really knew or could understand the peril inherent in atomic weapons they would demand of their various governments a real solution to the problem of war.

However, until such time as, by UNO or other action, all chance of major wars is truly nil, no policy is sound which is based on the assumption that atomic weapons will be outlawed for all time to come. Time will be needed for the gradual evolution of national and international thinking and resultant policies on the use of atomic energy in general, and of atomic weapons in particular. Presumably any international agreements reached will contain provisions for the exploitation of atomic energy for peacetime uses. As has been stated to the Senate Committee, in this exploitation there will be built up supplies of active materials sufficient for many bombs. Thus there will always be a vast military potential which must not be forgotten. Furthermore I understand that the time for conversion of peacetime atomic energy plants to war purposes would be dangerously short. It should be realized that we risk the security of our country when we gamble that there will be time to detect and to take decisive action against any nation that violates its agreements before atomic disaster is upon us.

Our military establishment must not be excluded from research and development in the atomic weapon field. We cannot lean exclusively on any agency which concerns itself primarily with possible peaceful uses of atomic energy. Any commission such as that proposed in the May-Johnson” Bill must have as its primary concern the [Page 1203] military security of the United States. To accomplish that end the Army and Navy must have a major part in determining how atomic energy will be applied to national defense. If there are to be atomic weapons in the world, we must have the best, the biggest and the most; and the Army and Navy must not be divorced from their responsibility of defending the United States.

  1. Lot 57D688, the consolidated lot file on atomic energy, 1942–1962, located in the Department of State, including the records of the Special Assistant to the Secretary of State on Atomic Energy and the records of the United States Delegation to the United Nations Atomic Energy Commission.
  2. “Manhattan Engineer District” was the wartime code name of the atomic bomb development program; the designation continued to be employed after the nature of the project became public knowledge. General Groves transmitted this memorandum to Mr. John M. Hancock of the United States Delegation to the United Nations Atomic Energy Commission on June 10, 1946 (Department of State Atomic Energy Files).