"The train tracks crossing the city," states the US governmental report on the effect of the Hiroshima bomb, "were back in working order by August 8, two days after the attack." Only then did the gamma waves and neutrons manifest themselves in human bone marrow and start taking deadly effect. Even thin cement slabs near Ground Zero had stopped the radiation. The majority of the 80,000 deaths were caused by heat radiation, shock waves and flying debris.

40 year old Shugita Chiyoko, searching for her husband among the body parts strewn under the Shosoji Temple on August 7th, only recognised him by his feet. "My husband had a very high arch." The neighbours were amazed. "'We've been married for 20 years,' I said. 'I can tell by his feet that it's him.' Around his ankles were the leggings he'd worn when he left that morning. The rest was cut off."

Only in 1950 did American physicists start researching nuclear heat waves, measured in calories per square centimetre (cal/cm2). President Truman had had the thermonuclear, or hydrogen, bomb built in January. Its destructive potential, measured during the first test in November, was the equivalent of ten million tonnes of TNT, compared with twenty thousand tonnes for the Hiroshima bomb. But the real advantage of the new weapon lay in its thermal effect. Since the heat waves outstripped the shock waves, the data from the 1945 explosions were reviewed.

The fire storm that enveloped the area around Hiroshima had a radius of 1.5 km and a thermal output of roughly 10 cal/cm2. A one million tonne bomb would achieve 22 cal/cm2. But fire damage was hard to predict, as too many other variables are involved. What role is played by wind, temperature, humidity and the individual incendiary properties of each city?

Data to answer such questions had only existed for ten years. The Luftwaffe had pioneered bombing raids over Warsaw, Rotterdam and Coventry. But it was only since 1943 that the incineration of cities from the air had amounted to deliberate mass killing. The fire bombing of Hamburg killed 45,000 people overnight, more than the Luftwaffe had achieved in nine months of dropping bombs on England. Only eight weeks earlier,the fire in Wuppertal had resulted in 3,000 deaths, an unprecedented figure until then.

The fire in Wuppertal burnt in the air circulation pattern particular to enclosed river valleys. In Hamburg it was the dry summer heat; in Heilbronn, Dresden and Pforzheim it was winter snow. Tokyo was built almost entirely of wood and paper, Darmstadt of sandstone, Munster of brick. Hildesheim and Halberstadt were criss-crossed by narrow streets lined with half-timbered houses, Mannheim was divided into classic quadrants, Dortmund and Duisburg were made up of sprawling 19th century blocks. The thermonuclear planners delved into the fund of knowledge left by the area bombing of the Axis powers. This was the only way to understand how individual cities burn.

The historic fires in San Francisco, Hamburg and London had nothing in common with the procedure whereby in only 17 minutes (Würzburg) or 21 minutes (Dresden), cities were showered with hundreds of thousands of incendiary bombs. These sparked thousands of fires, which within three hours became a flaming sea, several square kilometres wide. Large natural fires normally have a single source, and are driven for days by the wind. But war statistics showed that such winds played a minor role in fires caused by bombs. The real destructive power was not in the wind that drives the fire, but in the fire itself, which unleashes its own hurricane on the ground.

Neither buildings nor people can escape the logic of the elements of fire and air. A fire starts, it sets the air in motion, fire and air form a vortex extinguishing life and all that belongs to it: books, altars, hospitals, asylums, jails and jailers, the block warden and his child, the armourers, the people's court and all the people in it, the slave's barracks and the Jew's hideout, the strangler as well as the strangled. Hiroshima and Dresden, Tokyo and Kassel were transformed from cities into destructive systems. The agent of change is the bomb war, and the bomb war is its construction site. Work continues to this day, it's a work in progress. There is hardly a nation not working at it, and the numbers are growing.

When 40 years ago, a handful of atomic scientists studied the complex chemistry and mechanics which the war generation had used to raze cities, they were seeking what no one had experienced since the war: military mass destruction in real time, the laboured route from Warsaw to Hamburg to Nagasaki.

The effectiveness of the methods - a carpet of bombs dropped from a thousand choreographed planes on holy Cologne in 1942, the flash of energy in 1945, brighter than a thousand suns, deadlier than 200,000 tonnes of TNT - sent a message: it works! And that which works, anyone can do. And if everyone can do it, it is highly unlikely that nobody will. This 'if' is purely a matter of belief and luck; it is actually the realm of hope and prayers. The 'how' on the other hand is a practical occupation. Since Hiroshima and Dresden, this 'how' has been worked on feverishly. How could similar death zones be made to be safer, more manageable, more cost-effective and larger?

The downfall of the two cities also tells an ugly story about the 'if' of the weapon of mass destruction. With the know-how in place, the grounds for deployment practically took care of themselves. In 1939, a few weeks after Otto Hahn's splitting of uranium had brought him closer to the laws of matter, research was launched into whether something like this could be used in a bomb. To describe this new source of energy, physicists Carl-Friedrich von Weizsäcker and Siegfried Flügge used an image: that the chain reaction in a cubic meter of uranium oxide would be sufficient to catapult Berlin's Wannsee lake into the stratosphere.

The Wehrmacht understood immediately saw that this image was on its head. Far more practical would be to drop a force like the Wannsee onto a city like Berlin. Either way this was a practical application of Einstein's formula E = mc2. Einstein, who fled to the USA to escape the Nazis, understood better than anyone the identity between understanding the world and destroying it. After Hahn's uranium experiments, phenomenal capacities for energy and destruction were available to all. In his day, immense resources, a monstrous character and access to uranium were required. Everything is much simpler today; you can just buy it.

When the monster Hitler battered France in May 1940, taking Belgium on the way, he also gained access to the world's uranium chamber: the Belgian Congo. This prompted Einstein to write President Roosevelt, advising him to counter the destructive potential in his formula. America should build an atom bomb as a preventive measure. To stop the annihilator Hitler from possessing it first, the free world must have a monopoly on it. Their bomb would arrive before his - to some extent, the weapon expression of his character: a machine of hell to overthrow the prince of hell. The only problem was that the bomb had to be built before the war was decided.

While the industrial giant USA embarked on the most formidable development project of all time, the military giants Germany and Russia competed for victory. Germany seemed to have the advantage in the autumn of 1942 as it stood at the heights of Caucasus and the banks of the Volga. Just next door lay Kazakhstan and Iran. Aside from these two front lines, thousands of kilometres apart, the Germans had another front about four kilometres over their heads. In the sky above Germany, the men of Prime Minister Churchill and Air Marshall Harris were fighting doggedly and with heavy losses. Since 1942 they had stopped bombing key military targets and started burning cities.

Because Germany had more factories than England had bombers, precision strikes on steel and hydrogenation plants were less painful than precision strikes on sparse aircraft. At the beginning of 1942, the 400 or so bombers did not present an insurmountable force for Germany's anti-aircraft guns and fighter pilots. Understandably, the bombers took refuge in the darkness of the night sky where they were more difficult to see. But they couldn't see much either, at most the vague outlines of a city.

A city like Hamburg, with 1.5 million inhabitants, cannot be bombed in 30 minutes with 3,000 tonnes of bombs. More time and more tonnage are needed. The British had to learn to burn cities. As one of their foremost fire strategists, Horatio Bond, explained, the navigational problem of "hit or not hit" could be solved by dropping 600,000 incendiary bombs on Dresden. The detonation bomb intended for the Krupp factory in Essen which lands instead on the Krupp hospital is a waste in military terms. Not so the incendiary bomb, because the hospital spreads the fire. All of the bombs pay off, because the city itself multiplies their effect. But the city fights them too, by extinguishing and choking the flames. The Royal Air Force and the US bombing fleet took three years to halfway master the technique of airborne fire bombing: the preparation of an inextinguishable inner city fire.

Between February and August 1945, in Dresden, Pforzheim, Würzburg, Halberstadt, Kobe, Osaka, Nagoya, Yokohama, Tokyo etc., a total of 330,000 people died in conventional incendiary attacks, 120,000 in nuclear ones. Four fifths of Japanese victims were buried without being identified. Dr. Shigenori, military air defence commander, wrote: "Countless bodies, clothed and naked, black as coal, were floating in the dark waters of the Sumida River. It was unreal. They were dead people, but you couldn't tell if they were men or women. You couldn't even tell if the objects floating past were arms, legs or burnt wood." Before they died, they had jumped into the water to escape the fiery air which braised their lungs and set their clothes alight. People ran from the burning zones with their belongings strapped to their backs, failing to notice when these caught fire. One mother slung her baby over her shoulder and only noticed when she stopped to catch her breath that the child was engulfed in flames. Those who jumped into the water were no better off. The liquid was bubbling like the air, and the swimmers cooked in it.

Had the Hiroshima bomb hit Tokyo instead, there would have been four times the number of dead. Theoretically, 1,000 bombers each loaded with 10 tonnes of conventional munition could also have achieved 300,000 dead, but it would have been more laborious and far less certain of success. In Germany in 1945, death rates in the tens of thousands were only achieved three times: in Dresden, Pforzheim and Swinemünde.

The difference between the methods of destruction is, put simply, that nuclear weapons themselves produce the pressure and heat energy that pulverises buildings, sears people and generates fire. The combination of burning and explosion in conventional operations takes a less direct path via the materials of the city. These must react to the various impulses of the finely tuned munition: roofs are torn up, windows shatter. Otherwise, the houses wouldn't become ovens, nor the cellars crematoriums; fire requires draught. The stone facades must channel the heat down to the foundations where the people are cowering.

There were cities like Berlin that did not work right. The width of the streets, the firewalls, the abundance of greenery and canals opposed the fire-injections and responded wrong. But Dresden's narrow streets, decorative old town and wooden buildings fed the fires according to plan. The carefully selected triangle between the Ostragehege park and the main railway station functioned as a "fire-raiser". The old cities, bent with age, testimonies to the distant past, were best suited to such attacks. Freiburg, Heilbronn, Trier, Mainz, Nuremberg, Paderborn, Hildesheim, Halberstadt, Würzburg: this avenue of German history shared the lot of Dresden in these months. For the allied fire bomb strategists, the study of their material composition was a science in itself.

In Watford, England, as well as in Eglin Field, Florida, and Dugway Ground, Utah, dummy towns were built complete with German and Japanese materials and inventories. This sort of thing requires thoroughness. Only real Japanese floor matting can be used, only the right number of real German toys in the German house. More woollen coats are stored in Germany than in Japan, in solid cupboards of oak, pine and beech. How many books, which curtains, what type of cushions? The German roof beams provide the crowning touch. Then the practise can start.

The practise is a success when the right combustibles meet the right materials. That is the most difficult part, because it has to be carried out from four kilometres up in the night sky.

Red and green lights mark the death zone as if drawn with a coloured pen. To drop all the munition into this lit frame, a new flight technique was developed in August 1944 over Königsberg, known as "the fan". The oncoming squadron crosses a designated point, in Dresden a sports field. That is the hinge. When the point is crossed, the aeroplanes fan out from each other, to the north-east and the south-east. Each plane breaks off at its own angle, and knows a distance measured in seconds from the hinge, called the overshoot. Each pilot is allotted a different overshoot. When it shows on the display, the bomb bay opens.

The fan flies at three altitudes. With exact wind calculation, the munition from all three altitudes fall in parabolic trajectories over the target segment, equally distributed. Then it's saturated. When an air force has achieved such a feat, it does not ask too probingly whether mass destruction is worthwhile from military perspective. There's nothing wrong in showing what you can do. What does not count now will count later, and then it should be done well. One can only rehearse for future wars in current ones. That hardens people in a different way.

When soldier Jack Couffer walked among the houses of the Dugway Proving Grounds in Utah in 1943, which, according to the Air Force "correspond to the type of housing in which 80 percent of the German industrial population lives", he started imagining things. "I looked in the empty windows and imagined with terrible clarity that the houses were inhabited, bursting with life, with people walking through the narrow alleys on their way to and from the factories, street traders, shoppers, children playing. It is easier to set a sterile place like that on fire if you whisk such fantasies away". The coming air war was no longer to be won with scruples. Five years later Curtis Le May, warhorse in the campaigns over Germany and Japan and then head of the US Strategic Air Command, comforted himself with the thought that as there were no longer any civilians, there was no longer anyone to protect. Otherwise he could not have run the office that developed the "Reaper" and "Trojan" plans in 1949 - 1950, in which 100 atom bombs were to be dropped on 70 Russian cities causing 2.7 million deaths. The plan was based on assessments General Le May had brought home from Japan. "We knew when we burned a city back then, that we would kill many women and children. The aim of the strategy is to destroy the enemy's war-making potential. All that had to be obliterated." The Japanese had a complex and broad-based manufacturing system. "You only needed to walk through one of our roasted targets and take a look at the ruins of the countless tiny houses. Some kind of drill press stuck out of every pile of rubble. The entire population was involved in building aeroplanes or war munition. Men, women and children." That's why they were slaughtered in the Second World War. "There are no innocent civilians. Nowadays you fight a people, not armed forces."

When whole populations have to be exterminated, it is no wonder that 10,000 US nuclear warheads were amassed at the time of the Berlin and Cuba crises. Four hundred would have been enough to wipe out a third of the Russian population, which was 200 million in 1960. Defence Secretary Robert McNamara wanted to keep US casualties below 20 percent in the event of a skirmish. More would not be acceptable. As a result, 10 percent - a loss of 18 million - would be accepted.

Einstein had long lived in horror of his bomb, which was supposed to erase evil from the planet. It was evil itself and the evil was his creation. The special weapon against Hitler lost its addressee before it was ready. And already in November 1944, secret service intelligence suggested that it was a false alarm. Hitler's weapon of mass destruction didn't exist. The Germans were lagging way behind in these arts and would not achieve much more in this last of their foreseeable wars. General Eisenhower was already in Aachen, and Marshall Zhukov was on the Vistula. Both the same distance from Berlin.

While the armies raced against each other to take Hitler's last bastions - the economic one in the Ruhr region and the political in Berlin - the atomic physicists were racing against the end of the war. It looked as though the military campaigns would be over before the bomb was ready. If Hitler - the bomb's cause and intended object - was no longer a viable target, Roosevelt and Churchill had agreed that, under certain circumstances, Japan might serve the purpose. But these circumstances were being taken care of, one after another. Like the Third Reich, the Empire of the Sun was militarily and economically knocked out, cut off from the sea and without a supply of oil, metal and foodstuffs. It was defenceless against Le May's fire attacks. Moreover, the US de-coding service, which had broken the diplomatic code to the Japanese Embassy in Moscow, reported breathlessly that Tokyo was imploring Stalin to intercede for peace.

The uranium bomb was also non-essential because the fire hurricanes were capable of equally respectable damage. Moreover, it had just been established in Germany that surgical strikes on oil lines and transport routes caused far more military damage. With the German fighters grounded for lack of fuel, attacks could be carried out with practically no losses. This also made conventional mass destruction unnecessary. The relatively ineffective emergency stopgap would not, thankfully, be necessary; now there was something better. It was clear that the Allies would be victorious, Hitler and Albert Speer knew it as well. On January 30th, Speer, the Minister for Armaments and War Production, announced to Hitler that the country's economy would be demolished in four to eight weeks. "After this collapse, the war can not be continued, also from a military perspective." An accurate calculation.

But none of the war lords were clear on what kind of a political circumstance was to be established after these eight weeks on the shattered continent. At least Stalin knew what he wanted. Hitler knew things were out of his hands. All he could do was drag as many people as possible with him into death and leave all that remained standing in Germany to be decimated. Hitler's instructions to Speer and the regional Nazi leaders dovetailed with those of the two remaining war leaders; Churchill and Roosevelt unleashed with their 3,000 aeroplanes an "around-the-clock-bombing", which Basil Liddell Hart, the greatest British military historian of his day, termed "the Mongol devastations". Two thirds of the bomb tonnage of the five year air war fell in February, March and April of 1945, most of it on militarily insignificant targets. The tiniest part of this tonnage, the precision strikes on the 16 major train routes connecting the Ruhr region with the rest of Germany, had the greatest effect.

The Western Allies had assigned most of their resources to building up their strategic air forces. Their future empire was to be based on this weapon, even better when combined with a nuclear load. Even if there was no suitable recipient for the nearly complete super bomb other than the mortally wounded Japan, War Secretary Henry Stimson, the bomb's greatest advocate, already saw himself in possession of the "most terrible weapon ever known in human history". The bomb had cost two billion dollars. A huge amount of money at the time, but little compared with the sums invested in the worst, or possibly second worst, despot in human history. The lord of the Gulag received ten billion dollars in war goods and supplies to conquer the lord of Auschwitz. The investment paid off.

At the price of over 20 million dead, Stalin had defeated the strongest army ever assembled, which in four years had put a total of eight million men on a breadth of front spanning a maximum of 2,500 km. No other military leader was capable of such a defence. But it was only possible thanks to 17 million tonnes of supplies from his Western partners. For them, the postwar balance sheet looked as follows:

On the assets side were the two billion dollars invested in the military trump card, the atom bomb. On the other side were liabilities of 10 billion dollars, which had promoted the monster Stalin to ruler of the continent. The way the war had progressed, the downfall of Hitler's Germany could only lead to the hegemony of the Soviet Union over Eastern and South-Eastern Europe. And how the impoverished peoples of Southern and Western Europe - Italy, Greece, France - would situate themselves with respect to the political ideology of the invincible Soviet Union was uncertain. The outcome, unavoidable as it was, was not what the two leaders wanted. Neither Churchill nor Roosevelt could come to terms with this disaster.

At the Crimea conference of the big three in Yalta, Churchill recalled why his country had marched against Hitler. "Great Britain entered the war to defend Poland against German aggression. We stand beside Poland because it is a question of honour. Great Britain will never accept a decision which does not give Poland the security of ruling on its own territory."

Stalin, whose forces had now been in Polish territory for three weeks, responded that he understood Churchill's code of honour. "For Russians, however, the Polish question is not only one of honour, but also of security." Russia had previously sinned against Poland, he said, and the Soviet government was keen to make good. "But the core of the problem lies significantly deeper. In the course of the last 30 years, the Germans have marched twice through Poland to attack our country. Why could the enemy march so easily through Poland until now? Above all because Poland was weak." Stalin had by then installed his own followers to form a government that would make the Polish strong, free and independent.

"The British government", said Churchill, "believes that this government does not represent even one third of Polish people." Stalin responded that he would like to speak in his capacity as a military man. "As a soldier, what do I demand from the government of a country liberated by the Red Army? I demand that this government guarantee peace and order in the hinterland of the Red Army, prevent a civil war behind our front, and not stab us in the back." In his view, neither the men of the government who had fled to London in 1939 nor their underground fighters had done that. They had attacked Russian weapons depots, had already murdered 212 Red Army soldiers, and violated his orders concerning the operation of radio broadcasts. When they are arrested, they complain. "If these forces continue attacking our soldiers, we will shoot them."

Because these forces were already acquainted with Stalin when he and his partner Hitler divided Poland and liquidated its officer corps, they blamed the Russians for the annexation of their territory in 1939. East Poland had now been re-conquered; it was and remained White Russia. Stalin did not want his current partners to steal from him what Hitler had given him in the past. He offered the Poles one third of Germany as compensation. To keep this territory in the long run, they should get used to being protected by him.

"The Polish question has given the world headaches for five hundred years," sighed Roosevelt. In Churchill's view, it was necessary to ensure this would not continue. "Absolutely!" agreed Stalin. His headaches had diminished somewhat. All the ground in the East and South-East that Hitler had once subjugated was under Soviet control within a short period of time. And there was no one in sight to challenge him for it. Since advancing onto German territory in September, his Western allies were making extremely slow progress.

When the Germans started a counter-offensive from the Eiffel into the Ardennes killing 76,000 men, the nerves of the Western chiefs of staff were frayed. In Italy, their troops had been crawling for a year and a half up the boot and had hardly made it past Ravenna. Churchill wrote Stalin inquiring "whether we can count on a major Russian offensive on the Vistula front, or elsewhere, during January. I see the situation as urgent." The Red Army, which had beaten the Wehrmacht colossus from the Volga back to Warsaw with incomparable martyrdom, had to quickly relieve the pressure on the inexperienced troops on the allied Western front.

Four weeks later in Yalta, Churchill expressed his admiration for the power of the operation which had begun on January 12. "The winter offensive was the fulfilment of our duty of comradeship," said Stalin, adding that he had recognised "that the Allies needed them desperately." They got a lot:

In 18 days, according to deputy chief of staff Aleksei Antonov, the Soviets had advanced up to 500 kilometres in the general thrust of the attack. "On average, we advanced 25-30 km in 24 hours." 400,000 Germans had been killed or taken prisoner.

The Western powers remained where they had stood for the last four months, on a line roughly between Aachen and Saarbrücken. The respective distances of the Allied and Soviet troops from Berlin, more or less equal until the second week of January, had now changed dramatically. Marshal Zhukov was poised on the Oder near Küstrin, 70 kilometres from the German Reichskanzlei.

"How Poland was freed, and how the Red Army drove its enemy from the country," said Churchill cryptically to Roosevelt, "is a development of major importance". In Roosevelt's cabinet it had been discussed for some time. At the end of October 1944, Averell Harriman, the US ambassador in Moscow, reported to War Secretary Stimson "how the Russians are attempting to force their rule on the countries they have 'liberated', and the use they make of their secret police in doing so." For Harriman there was no difference between the Gestapo and the GPU, the Soviet secret police. US liaison officers had reported similarly on the cold contempt of Poland's liberators, their plundering, murders and rapes. Churchill wrote to Roosevelt in April that it was necessary to get as far east as possible to curtail Stalin's excesses.

From autumn to the following spring, the Western Allies came to see that their "war comrade", who had won the liberation campaign, had his own way of reading the events. Making him see things differently was impossible. In late March and early April, the other Allies were just warming up their military muscles with the encirclement of the Ruhr region. No wonder; they outweighed the German forces 12 to 1. The German Western Army stopped fighting. Their tanks stopped moving. Petrol and the will to fight ran out at the same time. But in the military twilight of February - March, the West took a nervous look at the Soviet military steamroller, rolling forward with no regard for casualties, and loaded the bombs. The occidental Mongol devastations could begin.

Stalin had nothing comparable to this airborne might. While his men could walk 30 kilometres a day, Churchill's bombers could fly at 300 kilometres per hour. The Russian army took 18 days to get from the Vistula to the Oder. But the British planes reached Dresden from the British Midlands in just five hours! After a 40 minute operation, the city is a heap of rubble, strewn with 35,000 dead. At a distance of 110 kilometres from the first lines of Marshall Konyev's troops which were in the process of liberating Upper Silesia, this is, to put it mildly, the demonstration of a capacity. If not a military capacity, then at least the capacity of a military. Konyev, the conqueror on the ground, did not profit militarily from the attack and took no notice. Zhukov would later castigate the barbarianism of his allies in Dresden; from that point on, they were his arch enemies. But what were they in February 1945? And what was Zhukov for them in September 1939? An ally of Hitler's in the subjugation of Poland. In one and the same war, enemies became partners, partners rivals and then partial enemies once more. The Cold War fronts replaced those of the World War as if by an invisible hand. The interfaces are Dresden in Europe and Hiroshima in Asia. In these theatres of slaughter, it is no longer possible to distinguish between partnership and enmity.

In Yalta, where bluffs were camouflaged in rhetoric and threats wrapped in hugs, Russia requested the help of its Western comrades in the storming of Berlin. Perhaps a final courageous ground initiative in the Rhine valley or Italy to join and engage the German troops. Or an air attack on the rail systems in Berlin, Leipzig and Dresden that would disrupt the transfer of Wehrmacht forces from the Western to the Eastern front. There was more courtship than need in the request and it didn't cost anything to ask. The Western colleagues promised air support, although this was the last thing they were interested in providing. Yes, they smashed every railway station and train wagon they could find. But to stop troops that were taking off for the East before their eyes? Why, to let themselves be shot by them?

The British documents on Dresden give troop transports as the target of the attack. But this was not the objective of the night attack. At noon the next day, the Americans superficially bombed the railway installations, which were the first to be repaired. But they did not start a fire storm. The British flew a perfect fire storm attack, not at all interested in the important shunting areas and bridges. The paltry weapons parts produced in Dresden appear nowhere in the otherwise very detailed RAF inventories. They were irrelevant when compared with what Zhukov possessed: five times as many tanks, seven times as much artillery an 17 times the number of aeroplanes. The local military barracks remained unscathed by all these waves of attacks.

Like the bombing of Hiroshima, Dresden's destruction has ever since been bound up with the question: "Why?" Two attacks with maximum overkill, each on a hopelessly defeated people! In the final spurt between the German and the imminent Japanese capitulations, the atomic physicists perfected their work with a test explosion whose lightning a blind woman claimed to have seen. Some of them started to grumble: "Why?" What had begun as an attempt to stop Hitler's world domination was being directed at the last convulsions of a checkmated aspiring power. Certainly, the last Samurais would have prepared a bloody welcome for the invading forces. But what was forcing the marines onto the treacherous beaches? America could rely on the strangling grip of its sea blockade, its airborne superiority and its precision bombing. Time was on its side.

Perhaps, said the sceptics, we could simply demonstrate the omnipotence of the wonder weapon, without using it on people. We could drop it over the ocean! Scientific director J. Robert Oppenheimer, in contrast, saw through the logic of mass destruction: "It needs the impression". Threats don't impress, willingness does. If you don't kill 100,000 defenceless people, nobody will believe you. Technical know-how must be accompanied by an iron will. A nation must act with a clear conscience, the proof will suffice for a generation.

The puzzle of who President Truman wanted to impress has been solved by the records. He was hoping the test explosion would coincide with the opening of the Potsdam Conference in July. Oppenheimer named the test after the godhead: Trinity. But the three gods disagreed on many points, such as Russia's entry in the Japanese War. At Yalta, in a moment of weakness, Stalin had promised to attack the Japanese protectorate in Manchuria, the industrial paradise just north of Beijing. The strongest defence troops were stationed there.

But after all that had happened with Stalin in Poland, Czechoslovakia, Hungary and Romania, his comradeship was turning into something sinister. The two Atlantic empires now wanted less of it, but couldn't rid themselves of their Eurasian third, the devourer of continents. What was stopping Bolshevism from taking over China, and then Korea? Russia had always had its eye on Japan; invasion losses were of no importance to it. The only thing that could keep the giant in check were the apocalyptic 'Little Boy' - the slim uranium bomb - and 'Fat Man', the pot-bellied plutonium bomb.

Decisive was not Japan's capitulation; that was already decided. But it had to capitulate as quickly as possible, and exclusively to the USA. The sequence of events speaks louder than words: August 6: 'Little Boy' on Hiroshima. August 8: the Soviets invade Manchuria. August 9: 'Fat Man' on Nagasaki. August 14: Japan capitulates to the USA. August 21: Japan capitulates to Russia. August 28: Japan capitulates to Mao Tse-Tung. The war ends.

But the principle of mass destruction has no natural end. After killing 100,000 random souls, no command prohibits the killing of ten million. It is not a matter of principle, but of what you can accept. Mao Tse-Tung, who forged Red China in 1949 out of the collapse of Japan, said he could easily replace 300 million losses. In a population of one billion, that's 30 percent. One would take the Maos and McNamaras for blusterers, were it not for the fact that the tools for putting their words into practise do indeed exist.

In figures, Dresden and Hiroshima were short steps in the war of mass destruction. They lie just one generation back, and have deterred repetition, because they were seriously realised. Not that there was no other way out. From a military perspective, both cities burned to cinders needlessly. When Churchill gave the order to set Dresden alight, he thought of the hordes of refugees from Breslau and Silesia: "Tan the Germans' hide as they retreat from Breslau", "create panic and confusion on the administrative and evacuation routes", "terror with military pretence", as he wrote six weeks later. In this way the Royal Air Force was somehow a player in the collapse and reconstruction of the architecture of power in Central Europe. It gave the signal, even it could not control the ensuing events.

The forced partnership with Stalin's fractious rogue state also made necessary the spectacle of the two atomic mushrooms. The liberators of East and South-East Asia curbed the oppressor at their side, to prevent him from gaining ground in this hemisphere as well. Yet another signal that had little effect. China was lost, and so was North Korea, over which the next war would have to be fought. Tiny, specious advantages, acquired with the curse of a weapon of mass destruction that will never go away, but is set to grow. Its first deployment went without a hitch. The know-how was there, and there was no alternative. Some people are probably still saying that.

*

The article originally appeared in German in Die Welt, on 10 February, 2005.

Jörg Friedrich was born in 1944. Since the 70s he has written extensively on the legal history of the Second World War, and the NS war crimes. His Book "Der Brand", on the Allied bombing of Germany, achieved international acclaim. Jörg Friedrich lives as a freelance author in Berlin.

Translation: lp and jab.