Nuclear strategy was the product of two lines of scientific and technological development, both of which can be traced back at least to the start of the twentieth century. The first, which began with the study of radioactivity, concerned the structure of the atom and the amounts of energy that might be released if the circumstances in which atoms broke up could be better understood. The second was the possibility of heavier than air flying machines which had been discussed during the previous century as a possibility and became a reality in 1903 when the Wright brothers completed the first manned flight at Kitty Hawk, North Carolina.
Our textbook image of the atom is one of a small solar system, with a heavy, positively charged nucleus, made up of protons and neutrons, orbited by light negative electrons. As each atom is electrically neutral, the number of protons in the nucleus is equal to that of the outer electrons. The atomic number of an atom, and its fundamental chemical properties, is determined by this number of protons. The number of neutrons in atoms of the same element is not necessarily constant. Variations, which can lead to differing properties, are known as isotopes. They are distinguished from one another by quoting the total number, neutrons plus protons, of particles contained in the nucleus (e.g. Uranium235). A key characteristic of neutrons, which makes them potential agents of change in a nucleus, is that they are uncharged. Only certain combinations of neutrons and protons are stable. When few in number, equal amounts of protons and neutrons result in stability, but for larger nuclei, the proportion of neutrons required for stability is much greater.
The potential instability of certain atoms, to the point where one element transmutes into another, was originally explored through the study of radioactivity, a term coined by the French scientists Philip and Pierre Curie to refer to the emissions they detected coming from unstable isotopes of heavier elements. These discoveries began in the late nineteenth century. Almost immediately the possible military implications of the energy contained in individual atoms being released was recognised. The futurist H. G. Wells, who had already contributed a dire warning on the impact of airpower, published The World Set Free on the eve of the First World War, which imagined pilots throwing ‘atom bombs’ onto enemy cities.1 As the workings of the atom came to be better understood other works of fiction also discussed the possibility. In Harold Nicolson’s Public Faces (1932), a British atomic test accidentally destroys Charleston, South Carolina as well as several other American cities. Nicolson was provided the name ‘atom bomb’ and technical information from science writer Gerald Heard.2 Other fictional works during this period discussed the atomic bomb specifically, as well as the weaponization of atomic-related components, for instance ‘radioactive dust’, and dealt with such issues as atomic demonstrations, deterrence, the failure of deterrence, and disarmament.3
1932 was the year in which the neutron and its role was been identified by James Chadwick. That year experiments by Enrico Fermi involved fission but he misunderstood his results and offered an alternative explanation of the phenomena he had observed. In 1933 Leo Szilard, an émigré scientist, born in Hungary living in London, who had read the books by both Wells and Nicolson,4 was bothered by a report of a speech by one of the pioneering students of radioactivity, Ernest Rutherford. Rutherford was of the view that transforming individual atoms would be an inefficient way to release energy. According to Szilard the reason why Rutherford was wrong came to him as a revelation as he crossed a road. If the neutrons released when individual atoms were split in turn went on to split other atoms then a chain reaction could result resulting in a massive release of energy. So alarmed was he by this discovery that he patented his description of a self-sustaining chain reaction in secret.5 In December 1938 Lisa Meitner, an Austrian scientist who had moved to Sweden to escape the Nazis, heard from the German Otto Hahn of an experiment in which Uranium appeared to turn into Barium. With her nephew Otto Frisch she realised that incoming neutrons had caused the Uranium atom to split. This phenomenon was named fission by Frisch, because of its similarity to the division of a biological cell.6
As a result of this intensive period of research by early 1939 the international scientific community understood that when uranium atoms were bombarded with neutrons they could split into approximately equal parts with the release of enormous quantities of energy. They also knew that when fission occurred some free neutrons were released which were capable of causing fission in other nuclei which could in principle result in a chain-reaction, spreading through a mass of fissile material and yielding enormous power. An atom (or fission) bomb was therefore a theoretical if not yet a practical possibility. It required a chain-reaction to create an explosion. This required an amount of fissionable uranium or plutonium isotopes (U233, U235 or Pu239) to reach a critical mass from which free neutrons could not escape or be captured by non-fissionable material. In addition, for explosive purposes, this reaction would need to build up extremely rapidly, for otherwise the device would fly apart and the reaction would stop. It was the brevity of this period that caused most technical problems in the construction of the first bombs.
As governments became aware of these developments, and with the real possibility of another European war, members of this international community had to pick sides. A German nuclear weapons effort began in April 1939, although many Jewish scientists who would have made a significant difference to the project had fled and came to make vital contributions to the British and then the American projects. The lukewarm attitude of many German scientists to the project and Hitler’s belief that the war could be and had to be won quickly, before such a weapon would be necessary, hampered its progress.7 In Britain, Winston Churchill, who had long taken an interest in nuclear energy, in part because he read closely the works of H.G. Wells, accepted a recommendation to establish an investigation into the possibility of an atomic bomb in June 1940.8 By July 1941 enough work had been done to demonstrate that a new and more powerful bomb using uranium might well be feasible. The key paper was written by Frisch, now based in Britain, and another émigré scientist, Rudolf Peierls.9
In the United States Szilard persuaded Albert Einstein, the most famous scientist of his day, to write to President Roosevelt warning of the possibility of ‘extremely powerful bombs of a new type’ and the risk that the Germans might produce them first. Just one such bomb ‘carried by boat and exploded in a port might very well destroy the whole port together with some of the surrounding territory’.10 Roosevelt took it seriously, although at first he only authorized exploratory research. In 1942, informed by the progress the British and Canadians had made, the Americans established what became known as the Manhattan Project. This immense scientific and engineering endeavour was tasked to see if fission—or atomic—bombs were feasible, and if they were, to build them.11 This was an enormous effort, led by recently promoted Brigadier General Leslie Groves from the Army Corps of Engineers and chief scientist Robert Oppenheimer. It was spread throughout the United States, with the central hub in Los Alamos New Mexico, where the bombs were designed, but also a large facility at Oak Ridge, Tennessee to enrich Uranium and Hanford, Washington to produce Plutonium. The first successful chain reaction was overseen by Fermi on 2 December 1942 in Chicago. In July 1945 the first Plutonium device was tested at Alamogordo in New Mexico. Two types of atomic bombs were constructed and used. The first, known as ‘Little Boy’, used Uranium-235 with a gun-type design, and was dropped on the Japanese city of Hiroshima on 6 August 1945. The second, known as ‘Fat Man’, was an implosion device using Plutonium. It destroyed Nagasaki three days later.
As we shall discuss below the attacks on Japan had their own strategic rationale, but this rationale depended on some fundamental shifts in the nature and character of war that had already taken place over the first decades of the century. The idea of dropping explosives on an enemy was not new. It had been attempted from balloons by the Russians on the French in 1812 and the Austrians on the Venetians in 1847. The first actual victims of an air raid were Libyan villagers attacked by the Italians during their 1911–1912 war with the Ottoman Empire. Alarms were further raised by the small-scale Zeppelin and Gotha raids of the First World War. In addition to the reality of air raids against defenceless populations it was evident that aircraft would acquire longer ranges and faster speeds. It was also unclear whether effective defences could be developed.
During the inter-war years it was almost taken for granted that the next war would open with vast air raids that would cause mayhem and slaughter. Particularly alarming was the possibility that the air raids would not merely drop high explosives and incendiaries on defenceless populations but also poisoned gas. Chemical weapons, another innovation from the past war, were at first seen as a means of attacking the enemy army, but, as with air power, the natural assumption was that having been shown to have such a crippling effect against soldiers there would be an even greater effect against civilians. So appalling was this prospect that an international agreement was reached to ban their use. The 1928 Geneva Protocol prohibited the use of ‘asphyxiating, poisonous or other gases, and of all analogous liquids, materials or devices’ and ‘bacteriological methods of warfare’. This depended for enforcement on the possibility of retaliation in kind, and so did nothing to prevent the production or stockpiling of such weapons. Few were confident that they would not be used in a coming war, although in the event this was one area where restraint was shown after 1939. The value of chemical weapons was limited against military targets and with civilian targets there were fears of retaliation.12
Any town which is within reach of an aerodrome can be bombed within the first five minutes of war from the air, to an extent that was inconceivable in the last war, and the question will be whose morale will be shattered quickest by the preliminary bombing? I think it is well for the man in the street to realise that there is no power on earth that can protect him from being bombed. Whatever people may tell him, the bomber will always get through.13
Around these expectations, and the rapid expansion of air forces after 1918, a strategic theory soon took shape. It was promoted by ambitious airmen making the case for a separate and autonomous service commanding a major share of the military budget and potentially able to win a war all by themselves. It appealed to a futuristic vision, attracted by the possibility of a more mechanised and efficient form of warfare, offering an alternative to the gruelling, murderous stalemate of the trenches.14 A bomber offensive capable of bringing matters to a swift conclusion could be contrasted with the previous war when the defences on the ground had prevented any sort of conclusion for four years.
This assumed that air power would be used in a particular way. The doctrine accepted that the most effective use of aircraft was to attack the social and industrial heart of the enemy, so producing internal collapse and obviating the need for a traditional battlefield victory. This in turn reflected the presumptions of total war. The whole society, rather than just an armed segment, had become intimately involved in the waging of war. Success was dependent upon the numerical and industrial strength of nations, and the willingness to concentrate them in a titanic struggle. In the war just ended this led to a process of mutual exhaustion, with defeat coming to those countries which collapsed first. Such wars involved severe drains on national resources and energies. They demanded patience and perseverance; a satisfaction with the enemy’s lack of progress rather than tangible progress of one’s own. Few military thinkers applied themselves to the perfection of the means of fighting a war of attrition.15 Soldiers do not like to plan for long-drawn-out and inconclusive campaigns. That is why they are often so unprepared to fight one when it is forced upon them. Aerial bombardment offered a new way to avoid attrition. Naval blockade contributed to the German defeat in the First World War by undermining its economy and adding to civilian misery, but its effects took time to have an impact. The impact of air raids would be felt immediately, and so too, it was assumed, would be their political consequences.
As the new air forces began to take shape, they offered a prospect of quick victories. This led them to play down alternative uses of airpower, for example in support of armies, and the possibility that ways could be found to resist a massive air attack. Bureaucratic and operational independence, the élan of the airmen, and the primacy of the strategic bombardment mission were all bound up in a general sense of the uniqueness, in its power and directness, of the heavy bomber.
This use of airpower was described as ‘strategic bombardment’. As we have already noted, this terminology assumed that bombardment of socioeconomic targets behind the enemy lines provided an independent means to the strategic end of enemy defeat. Adding the adjective ‘strategic’ to blockade or invasion or territorial defence would seem superfluous. Its use in the case of bombardment came from a desire to distinguish the envisaged role from that of a tactical variety, undertaken in support of surface forces in battle. This distinction between ‘strategic’ and ‘tactical’ roles made little sense for armies and navies. Here battlefield success, or the probability of such success, was an inevitable concomitant of the attainment of the strategic end. The distinction worked for the proponents of airpower because it differentiated between independent operations and those dependent upon other services. It also captured a belief, that later turned out to be fallacious, that strategic bombardment did not involve contact with the enemy’s forces. Air Marshal Trenchard explained: ‘It is not necessary, for an air force, in order to defeat the enemy nation, to defeat its armed forces first. Airpower can dispense with that intermediate step…’.16 This then created the issue of whether a government confident in its strategic air power could dispense with its army and navy. However impressed they might be with the potential of strategic air power none even considered going that far or even making such a capability an overriding priority.
The Italian Giulio Douhet organized the apparent logic of airpower into a systematic theory. Though the theory of strategic bombardment has come to be associated with his name it would be a mistake to overestimate his influence. Similar notions occurred to many airmen in many countries quite independently. The theory had a natural appeal. Here was an exciting, and still improving, new medium of warfare, capable of speedier and more distant operations than hitherto considered possible. Rather than dabble inconclusively in surface engagements on the periphery, how much more effective to aim right at the centre of the enemy’s power—the industries and workforce which sustained its military effort.
Much advocacy of strategic bombardment was immoderate and simplistic, relying on intuition more than analysis. In part, this was because it was propaganda for a new branch of the armed services. But even the most detached writers on this subject were working in the realm of speculation. They could not be sure what changes new technological advances would bring; they could only guess at the impact of bombardment on modern social structures. (In Britain, for example, much of the RAF’s confidence in strategic bombing derived from its apparent efficiency in controlling tribesmen in Somalia and Iraq.) Under the influence of these theories, military writers were straying beyond their area of competence. It might be hard to challenge military expertise on the tactics of battle; but now they were commenting on the ability of civilians, indeed whole societies, to withstand a certain sort of pressure.
Whatever its aims, the side which decides to go to war will unleash all its aerial forces in mass against the enemy nation the instant the decision is taken, without waiting to declare war formally.17
The belief in the critical importance of the first blow (and the readiness to abandon a principle of international law by failing to declare war) was based on the premise that this could be a war-winning event, less because of the physical than the psychological consequences. The total paralysis of society would require time and favourable conditions. However, the proponents of strategic bombing believed that the desired result would come earlier because of the vulnerability of civilian morale to aerial attacks. Before bomb damage had made it impossible to sustain fighting forces at sea and on land, the collapse of morale would lead to offers of surrender.
The identification of morale as a critical target was borrowed from those conventional theories of warfare in which the morale of the armed forces was emphasized as being as much a critical determinant of strength as numbers and equipment. The Prussian theorist of war Carl von Clausewitz wrote in his book On War, of the importance of ‘spirit’, describing physical force as the ‘wooden hilt’ of the sword, whereas moral force was the ‘shining blade’.18 At the time when the early theories of strategic bombardment were being formulated ‘morale’ was a central concept in military thought. The French Army in particular, inspired by the theories of Du Picq and Foch, saw war as the clash of opposing wills, with defeat the punishment of the force whose will broke first. There had been a tendency, which Foch mournfully acknowledged after World War I, to believe that ‘morale alone counted’, seeing victory as almost a triumph of mind over matter.19 But even those who kept the moral factor more in perspective did not deny its importance. Bad morale meant indiscipline and desertion; good morale meant resourcefulness and courage on the battlefield.
Focusing attention on to civilian morale as well as that of the armed forces seemed appropriate to an age when warfare was losing its separateness and becoming a test of strength between whole societies rather than simply the armed representatives of those societies. The welfare of civilians had always been at stake in warfare, but until the nineteenth century their contribution to performance in war had not been significant. Even in sieges non-combatants were more of a drag than a spur, spoken of as bouches inutiles—useless mouths. With warfare relying more upon a society’s total resources of manpower and industrial capacity, the roles of ‘national will’ and a smooth process of war production grew in relative importance. The ability to interfere with production and undermine the national will might be as important as battlefield successes in weakening the enemy. Civilian suffering might be a cause of defeat—not just a consequence. Furthermore, civilian morale appeared as a more attractive target than military morale. Civilians were unready to face military danger and lacked discipline when it came. So Douhet argued that there would be no need to pound at the sturdy and prepared military shield provided by the army and navy. The ‘air arm … will strike against entities less well able to resist, and helpless to act or counteract. It is fated, therefore, that the moral and material collapse will come about more quickly and easily.’20
A complete breakdown of the social structure cannot but take place in a country being subjected to … merciless pounding from the air. The time would soon come when, to put an end to horror and suffering, the people themselves, driven by the instinct of self-preservation, would rise up and demand an end to the war.22
Writing in 1923 the British military theorist Major General J.F.C. Fuller wrote about how London would be transformed into a ‘vast raving Bedlam’ following an air attack and how the Government at Westminster would be ‘swept away by an avalanche of terror’.23
On both sides during World War II there were assertions that the enemy élite in crucial ways was alienated from the mass, committed to the war for its own purposes but able to use the state apparatus to mobilize the mass to follow its lead. There was an obvious propaganda element in such assertions. At the same time, they reflected a widely-held assumption that the government’s hold over the population was tenuous. In this sense the mass was the élite’s ‘Achilles heel’—a soft target that was also the foundation of the national effort. Aerial bombardment would jolt the populace into an awareness of the risks they were running for the government’s war policy. The relationship between the mass and the élite would be disrupted: either the people would cease to do the bidding of the government through a generally lack-lustre approach to war projects or else, preferably, they would demand of the government that it sued for peace.
Even accepting a crude élite/mass distinction such reasoning suffered from three fallacies. The first was the belief that a change in attitudes would automatically result in a change in behaviour and that this would take the form of activism rather than apathy; second, that the means would be available for mass activism to transform the government’s conduct of the war. The third fallacy was that even if mass behaviour was affected that this would favour the attacker’s objectives. In the event it could also be used by the ‘elite’ to bolster national will against the attacker.
It was true that military morale could be built and reinforced more readily than that of civilians, but the consequences of its collapse were also proportionately greater. A despondent and dispirited leadership was a recipe for battlefield disaster. Even for the individual soldier—normally controlled within a command structure—the physical proximity of the enemy meant that there was an option to desert or surrender. Direct and immediate results could flow from a collapse in military morale in a way in which they were unlikely to do with a collapse in civilian morale. Because of the lack of immediate consequences and the added difficulties facing an enemy attempting to press an advantage, recovery was more possible at home than at the front. So long as the economy was functioning sufficiently well to service the military machine, and this was itself performing adequately in combat, the strategic impact of a miserable and dejected population was limited, though it might be a source of vicarious pleasure for the raider. It could be hoped that a government that sympathized with, or indeed experienced, the suffering of the people would be so appalled that the desire for relief would cause a reconsideration of the national commitment, but there would be no compelling reason why it would do so.
In practice the objective misery of the population, whether resulting from bombardment or scarcities or battlefield losses, was not critical on its own. As, if not more, important were basic factors of social cohesion and political structure, as well as more specific ones relating to the extent of the understanding of and support for the war policy and its execution. To replace a government, or to get an existing one to change its mind, required both political means and an alternative policy. ‘Peace’ could suggest far greater evils if it was firmly believed that ‘democracy’ or ‘civilization’ was imperilled. Most important, for a fundamental change to take place there needed to be an environment in which some form of opposition could develop and grow. This was always going to be particularly problematic in totalitarian and authoritarian political systems.
At the start of World War II, rather than embark on the course of uninhibited bomber offensives the belligerents exercised restraint. This was a consequence of uncertainty as to whether strategic bombardment could bring the war to an early and satisfactory conclusion plus the knowledge that it could well lead to reprisal raids.24 The devastation resulting from the systematic pounding of each others’ cities appeared as a frightening prospect. No government wished to cope with the consequent social and economic strains.
The British and French had an exaggerated sense of German bomber strength, while Hitler was anxious to prevent major damage to German cities. Moreover, the Luftwaffe’s role was more tactical, acting in support of ground forces. In issuing his commands at the start of the war, Hitler laid down a ‘guiding principle’ not to provoke the initiation of aerial warfare by an action on the part of Germany. The erosion of this mutual restraint, which did not take place until after the fall of France, stemmed from the fact that any use of airpower, whether seen as being ‘tactical’ or ‘strategic’ tended, at some point, to degenerate into an attack on civilians. Attempts to use airpower as a purely military and discriminating instrument floundered on inherent inaccuracies and the regular proximity of ‘civilian’ and ‘military’ targets, especially when ‘military’ was broadly defined. The ‘tactical’ use of airpower implied that it was to be contained within the combat zone. But a ‘combat zone’ was not a fixed space with rigid boundaries. Aircraft extended the area of the combat zone and, with tanks and other armoured vehicles, allowed much greater forward momentum in battle. Compared with the static fronts of 1914–1918, the battle arenas of 1939–1945 were remarkable for their scale, variability, and fluidity. The success of the German offensives of the first year of the war meant that cities were frequently to be found in the combat zone. As ‘tactical’ obstacles, and easier to denote as such when actively defended, cities such as Warsaw and Rotterdam suffered aerial attack.
When the Germans reached the Channel the potential combat zone included southern England. The Luftwaffe attempted to gain command of the air by destroying the aircraft, bases, and facilities of the RAF. The purpose of this effort was not to put British cities at the mercy of the Germans, but to provide clear skies for the planned invasion. It was in the course of the battle for the command of the air, the Battle of Britain, that the restraints on aerial warfare finally eroded. As a result of British raids of late August against Berlin, the blitz of London began. Rather than a catastrophe for Britain, by allowing the RAF a chance to recover from the severe damage inflicted to its facilities, the blitz was a relief, despite the suffering that Londoners had to endure.
The first year of the war demonstrated that the more extravagant claims of airpower enthusiasts had been erroneous. The sweep of the German armies through Europe upset notions of surface deadlock; there were forms of defence against bombers, such as radar-aided fighter aircraft, that could cause serious casualties in the offensive force; and the fragility of the civilian population in the face of air attack had been over-estimated. The Germans continued to test civilian morale, for the blitz continued after the invasion plans had been shelved in the vague and futile hope that it might force the British to reconsider their commitment to the war. What started as a support for an invasion turned into a surrogate. By 1942 the RAF had recovered, built up its offensive bomber strength and was being joined by the US air force. It was now the Allies’ turn to test theories of strategic bombardment. Here too, their adoption of the strategy was a surrogate. Unable to open a second front on the land, they contented themselves with battering the enemy from the sky.
An attack on the socioeconomic structure of the enemy was not a novel feature of British strategic policy. Accustomed to having weaker land armies than those found on the continent the means to victory had been seen to be the ability of the Royal Navy to enforce an economic blockade. This had contributed to victory in 1918 and was the foundation of British hopes in 1939. It demanded no great conceptual leap to suggest that bombers might achieve through direct assault what the Navy could only achieve through an indirect squeeze. If merchant shipping could be considered a legitimate military target so could industry, fuel, and communications. Here problems arose because airpower was an extremely blunt instrument. At sea there was no adjacent property to be damaged. This was not the case on the land where, even if the target was missed, something would be hit.
On top of this the RAF were sceptical as to their ability to pinpoint key industrial targets and destroy them with sufficient efficiency and on a sufficient scale to affect the course of the war. The bluntness of the air instrument stemmed from a requirement, if prohibitive losses were to be avoided, of night action. This added to the already considerable inaccuracy of aerial bombardment. What was practically easier became strategically desirable. Point attacks against specifically identified vulnerabilities in the military or industrial structure were dismissed as ‘panaceas’ and the effort was concentrated against ‘the morale of the German civil population and in particular of the industrial workers’. As Liddell Hart caustically noted: ‘inaccuracy of weapon-aim fostered inhumanity of war-aim’.25
The American airmen were more anxious to aim for military industrial targets and even attempted day-time raids, in which they were extremely vulnerable to enemy air defences, to improve accuracy. While obviously less costly in civilian lives than area attacks, civilian losses could not be avoided, even when the targets were in occupied territories. Nevertheless, purposeful attacks on vulnerable parts of the military-industrial structure did show results over time. Eventually, the allied bombing offensive disrupted the war economy and denied key supplies to the enemy forces. The value of attacks on civilians was less obvious though strongly asserted by those promoting the attacks. The bombing surveys conducted after the war cast doubts as to whether civilian morale was seriously strained through bombing attacks. Even accepting that there was a threshold of tolerance for a society and that it could adapt to a systematic pounding only up to a certain point, this point was not reached early in the war. The long-range bomber did not appear as an instrument of a decisive early blow, but as another instrument of attrition.26 It could not claim to have superseded the other services because armies were still needed to occupy territory and navies to keep belligerents supplied or restrict their ability to trade.
As an attempt to regulate political behaviour and decisions through inflicting pain on the populace it was not impressive. It was only after the war that the limitations on this form of attack were widely recognized. During the war itself they were suspected by some, but the prevailing atmosphere on both sides was one in which the capacity of the enemy to withstand pain was doubted and the desire to inflict pain, if only by way of retribution, was very strong. It was into this environment, with the mass slaughter of enemy populations endorsed as a strategy, that the first atomic weapons, were designed, constructed and employed.