Were the A-Bombs the Last Resort?

Last August marked the 75th anniversary of the atomic bombing of Hiroshima; three days later a second bomb obliterated Nagasaki. As early as August 9, the day of the Nagasaki explosion, the Federal Council of Churches of Christ wired President Harry S. Truman:

Many Christians deeply disturbed over use of atomic bombs against Japanese cities because of their necessarily indiscriminate efforts [effects?] and because their use sets extremely dangerous precedent for future of mankind. 

Truman replied:

Nobody is more disturbed over the use of Atomic bombs than I am but I was greatly disturbed over the unwarranted attack on Pearl Harbor and their murder of our prisoners of war. The only language they seem to understand is the one we have been using to bombard them.

When you have to deal with a beast you have to treat him as a beast.

Since then, debate has never subsided about whether it was morally justified to drop the bombs. This blog post will certainly not settle this question. My aim in the first part is simply to set out the terms of the argument. In the second, I’ll explain why it is such a hard question morally and legally. In the third part, though, I will suggest that the bombings may have violated the just war principle of last resort – and therefore that they may not have been militarily necessary.


We often pose the question this way:

Was it justifiable to drop the bomb on cities (killing tens of thousands of civilians) if the alternative was a bloody, brutal ground invasion of the Japanese homeland?

Let’s stipulate what seems overwhelmingly likely: a ground invasion would have cost hundreds of thousands of American lives, along with untold numbers of Japanese casualties – including Japanese and Chinese civilians. If so, might dropping the bomb, horrible as it was, have been a life-saver on a vast scale?

        Call this the “lesser evil” question, because it says that the A-bombs were a lesser evil compared with the next-best alternative, a horrifyingly bloody ground invasion. If the bombings were the lesser evil, doesn’t that justify them? It’s a hard question because of course lesser evils are still evil. That’s one side of the argument. But greater evils are, by definition, even more evil! That’s the other side.

        For some, and especially U.S. troops who were getting ready for the ground invasion, the answer to “was the bombing a lesser evil?” is a resounding yes. The historian Paul Fussell was one of those Marines. In 1981 he published a famous article called “Thank God for the Atom Bomb.” The title speaks for itself, and the article pulls no punches.

When the atom bombs were dropped and … we learned to our astonishment that we would not be obliged in a few months to rush up the beaches near Tokyo assault-firing while being machine-gunned, mortared, and shelled, for all the practiced phlegm of our tough facades we broke down and cried with relief and joy. We were going to live. We were going to grow to adulthood after all.

No doubt there were plenty of Allied POWs who felt the same way; and it isn’t hard to imagine that even some patriotic Japanese, both civilians and war-weary soldiers, shared Fussell’s reaction (even if they pushed it out of their minds as shameful).

        Fussell is angry. He heaps sarcasms on the “sensitive humanitarian” who “was not socially so unfortunate as to find himself down there with the ground forces, where he might have had to compromise the purity and clarity of his moral system by the experience of weighing his own life against someone else’s.” He argues that nobody is qualified to condemn the bomb if they never personally experienced “the unspeakable savagery of the Pacific war,” with its “crazy brutality and sadism.” That even includes other military personnel who were in the Pacific theater but not in the front-line fight. Even they are not entitled to impose “ex post facto a rational and even a genteel ethics on this event.” Nobody is entitled to judge other than those who saw combat at its worst.

        Fussell has a point, but he goes too far. Notice that he doesn’t mention the experiences of Hiroshima survivors vomiting from radiation sickness as they buried what was left of their families. They saw the bomb at its worst, which Fussell never did. They might answer him with his own argument: who are you to say how bad it was?

        The fact is that outsiders have no choice but to judge. Otherwise, current leaders could never draw “lessons learned” from the decision to drop the bomb. To guide future conduct, we have no alternative to a dispassionate moral analysis – humbly acknowledging that those who didn’t go through the horror can never know how bad it was. But we must beware of false humility that throws our own power of judgment out the window. False humility merely ducks the responsibility to think.

        With those cautions in mind, let’s turn to the lesser evil question. You can think about it in several ways: as a matter of morality and law, but also as a matter of historical fact. The next section looks at the law and morality, to explain why the question is so hard.

        Then comes the factual question: were dropping the bomb and a bloody invasion really the only alternatives? If not, maybe the “lesser evil” conversation is attempting to answer the wrong question.


        Start with the law and morality of war. Today, there is no question that deliberately targeting civilians, and using an indiscriminate weapon, are war crimes. This wasn’t as obvious 75 years ago. The law at the time only prohibited bombardment of undefended cities (Hague Regulations, art. 25). A 1922 draft of new rules that forbid aerial attacks on civilian targets, and terror bombing, was never adopted.

        At some level, people understood that attacking civilians is morally wrong – otherwise, those draft rules would never have been written in the first place. But in a total, existential, war where both sides were bombing cities, the morality became at least unclear. In Just and Unjust Wars, the modern classic of just war theory, Michael Walzer calls this a “supreme emergency” – and he admits that in a supreme emergency, ordinary jus in bello rules may not apply.

Yet here we need to be careful. The 1940 Battle of Britain really was a supreme emergency. Winston Churchill was not exaggerating in June 1940 when he said of the struggle to come: “Upon it depends our own British life, and the long continuity of our institutions and our Empire.” France had fallen, the U.S. was not yet in the war, and Britain was fighting alone.

        But the U.S. was never in that kind of supreme emergency, and especially not in 1945. It seems more plausible simply to say that after years of total war at an unprecedented level, moral lines that might seem clear now were not so clear, especially when there was no settled law to point to. Cities had been bombed for years by Allies and Axis powers alike. The fog of war was also moral fog. Americans were ware-weary and frightened for our troops, and the American people wanted above all else for the war to end fast. That, probably more than any studied moral reflection, explains the decision to drop the bomb within weeks of the July 16 Trinity Test in Alamogordo.

        But, the reply goes, there really is a rational moral justification for dropping the bomb: the lesser evils argument. Plausible estimates of A-bomb fatalities in Hiroshima and Nagasaki total about 200,000. (I don’t know whether U.S. planners had estimates of how many Japanese the explosions would destroy.) Estimates of U.S. casualties in the ground invasion varied widely, but none of them were lower than 200,000, and several were much higher. And this doesn’t include Japanese military casualties or civilian “collateral” damage, which would surely have doubled or even tripled the casualty count.

        If you think about these numbers and the “lesser evil” in utilitarian terms, it sounds like a trolley problem – do you take some lives to spare even more lives? – and  most people seem to think the answer is “yes” Drop the bombs!

        But there’s a competing principle: the absolute rule against deliberately killing the innocent, even to save the lives of others. (Here, “innocent” means simply “people who have done nothing to forfeit their right to life,” including non-combatants who have not taken up arms.) “Thou shalt not murder” is Ten Commandments morality – and, in military ethics, “Soldiers fight only enemy combatants” is Rule Number One on the U.S. Army’s “Boots on the Ground” list of ten “soldier rules” – the Army’s ten commandments.

        As a moral matter, we generally don’t think that it’s okay to carve up an innocent person to harvest their organs even if you could save five lives with the transplants. People aren’t fungible that way. The victim has done nothing to waive their rights, and the number of lives saved doesn’t matter – murder is murder. (Notably, in empirical Trolley Problem studies, people who opt for saving five lives at the cost of one change their view if the only way to stop the runaway trolley and save five people is to hurl a very large man in its path. Murder is murder.)

        Sometimes it’s said that Hiroshima was a legitimate target because it was “dual use.” In a May 1945 target list for the bomb, J. A. Darry wrote of Hiroshima, “This is an important army depot and port of embarkation in the middle of an urban industrial area,” and two months later another target list described it as “an ‘Army’ city; a major POE.” Neither was true of Nagasaki – but more importantly, the point of bombing Hiroshima was not to weaken Japanese military power, but to force quick surrender by wiping out a city. Dual use is no excuse.

        I cannot resolve the moral question here: the “lesser evil” argument poses a very hard question indeed!


        But what if we’re asking the wrong question? What if dropping the bombs and a bloody ground invasion weren’t the only alternatives? What if there were things the U.S. could have done to get Japan to surrender without launching a ground invasion?

        In just war theory, the principle of last resort says leaders needed to try those things before dropping the bomb; and the principle of military necessity concurs: using unnecessary violence to achieve a military end like enemy surrender is unjust.

        Here’s a quote:

“It is my opinion that the use of this barbarous weapon at Hiroshima & Nagasaki was of no material assistance in our war with Japan. The Japanese were already defeated and ready to surrender.”

Who said this? The surprising answer is: Admiral William Leahy – Roosevelt and Truman’s Chief of Staff, Chairman of the Joint Chiefs, and the first 5-star admiral in Navy history. Leahy adds:

“My own feeling was that in being the first to use it, we had adopted an ethical standard common to the barbarians of the Dark Ages. I was not taught to make war in that fashion.”

Admiral Leahy is not the only one to express such views. Here’s another:

“I voiced my grave misgivings, first on the basis of my belief … that dropping the bomb was completely unnecessary, and second because I thought that the country should avoid shocking world opinion by the use of a weapon whose employment, I thought, was no longer mandatory as a measure to save American lives. It was my belief that Japan was, at that very moment, seeking some way to surrender with a minimum loss of ‘face.’”

This quote is from another 5-star: none other than General Dwight Eisenhower.

            Why did Leahy and Eisenhower believe this? They don’t say, but it isn’t hard to guess: They understood that Japan was on the ropes, and that the Japanese were well aware they were on the ropes. Doubly so, because with the end of the European war the Allies could turn undivided attention to finishing off the war in the Far East.

        Well, what was the alternative to the A-bombs and the ground invasion? It would have involved two-step diplomatic push before doing either:

        Step One would be to tell the Japanese exactly what the U.S. meant by its demand for an “unconditional” surrender. More precisely, U.S. leaders could have clarified that all we wanted was unconditional military surrender, to remove the Japanese military threat permanently. As Secretary of War Stimson wrote to Gen. Marshall on May 30, 1945, the aim was “permanent destruction of the warmaking power of Japan.” We weren’t planning to hang Emperor Hirohito, who had nearly divine status for the Japanese people, or even to dethrone him. Nor was the American intention to exterminate or enslave the Japanese people, or destroy their economy. That was a real fear in Japan. Japan’s leaders surely understood how fiercely the U.S. public hated them. With those possibilities weighing on them, it’s no surprise that Japan was readying itself to fight to the finish.

        In fact, unconditional military surrender is all our military and civilian officials meant by “unconditional surrender.” Our own military leaders urged civilian leaders to say so publicly. It even went into the draft of the July 26, 1945 Potsdam Proclamation – but President Truman and Secretary of State James Byrnes deleted it.

        By refusing to clarify what “unconditional surrender” meant, we actually gave a powerful argument to the Japanese war faction against the peace faction. They could dig in deeper because they thought they were fighting to save the Emperor, and perhaps the Japanese people themselves.

        Step Two was getting the USSR to enter the war against Japan, which Stalin wanted to do after the German surrender. The USSR terminated its neutrality agreement with Japan back in April 1945 – so the Japanese could see it was coming. (In fact, the USSR declared war on Japan two days after Hiroshima, and one day before Nagasaki. Japan surrendered less than a week later.)

        And there is a great deal of evidence that most U.S. military leaders, and most of Truman’s advisors (except Byrnes) thought that this “two-step” strategy would bring about a surrender with no need for a land invasion. As mentioned, Japan was running on fumes, and after the German and Italian surrenders they now faced the undivided might of the Allies.

        Significantly, in April 1945, Japan replaced the hard-line militarist prime minister Koiso with the less militarist Admiral Suzuki. Suzuki replaced Koiso the day U.S. forces sank the Japanese flagship Yamato and a week after we invaded Okinawa.

        Historian Gar Alperowitz reports that Japan put out peace feelers in Portugal, Sweden, and Switzerland, and the OSS knew about it. And our own Joint Intelligence Committee thought the two-step would work.

        There is no question that a strong military faction in Japan opposed surrender – even after Hiroshima and Nagasaki. Less than a week after Nagasaki, hard-line militarists attempted a coup in order to keep Japan from surrendering. (After it failed, the coup leaders committed ritual suicide.) More importantly, there is no question that the Japanese Army was making preparations at Kyushu for a fight to the finish.

        But that’s what militaries do: prepare for the worst-case scenario, which was a ground invasion of the homeland. There is no reason to think the Japanese army would have disobeyed an Imperial order to surrender – and the Emperor had already told his cabinet that he wanted to negotiate peace terms.

        So the question is: why didn’t we try the two-step strategy of clarifying what unconditional surrender meant, and waiting for the USSR to declare war?

        Nobody really knows, but there is historical evidence to support four theories:

Theory 1: Since April 1945, the USSR and the U.S. were already in a deadlock over the fate of Poland and Eastern Europe more generally. U.S. leaders became fiercely suspicious of Soviet intentions, and for good reason.

        For that reason, Secretary of State Byrnes didn’t want the Soviets to enter the war and invade through China, even if Soviet entry would have brought a quick Japanese surrender. He wanted the war to end before Stalin had a chance to move east, to minimize Soviet influence in Asia. President Truman agreed, and they deliberately delayed the Potsdam meeting with Stalin (where these matters were discussed) until after the July 16 Trinity test proved the bomb worked.

        That’s Theory 1: since we didn’t want the Soviets to jump in, we wanted to end the war fast. The bombs were the quickest way to accomplish that.

Theory 2: Some U.S. officials thought that unless the Japanese suffered extreme homeland devastation, then even after surrender they would never give up their militarism – fueled by nationalism and revanchism. It was the same logic as in Germany. There, defeat in World War I didn’t end German militarism. Germans consoled themselves with the myth that they had been “stabbed in the back” by civilians. Allied thinking in World War II was that Germany must not only be defeated, but so crushed that no myths could keep German militarism alive. The same thinking might apply to Japan.

Theory 3: Some historians speculate that the American people would have been furious at anything less than an unconditional surrender – so the first step of the two-step strategy wouldn’t fly politically. A Gallup poll in 1945 showed that a stunning 13% of the American public wanted to exterminate the Japanese people. (George Gallup, ed., The Gallup Poll: Public Opinion 1935-1971 (Random House, 1972), vol. 1, pp. 477-78.)

        Theory 4: U.S. leaders were already looking ahead to a world where they wanted a strategic nuclear arsenal. There was a real question whether Congress – which was already skeptical of the $2 billion Manhattan Project – would pay for it if there wasn’t an unmistakable demonstration of what A-bombs could do. As Stimson quipped, “I have been responsible for spending two billions of dollars on this atomic venture. Now that it is successful I shall not be sent to prison in Fort Leavenworth.”

        Now, on all four of these theories the decision to drop the bomb makes geopolitical sense – and also domestic political sense. BUT, in moral, just war terms, the reasons are totally unacceptable. They involve incinerating thousands of civilians for political reasons having nothing to do with the war, or with avoiding a ground invasion.

        An important caveat: all of this history is debatable and hotly debated. And of course different U.S. decisionmakers did not all have the same motivations or follow the same reasoning. So, in the same way that the moral arguments can be debated, the historical arguments can as well.

        But there seems to be no morally valid reason for not trying the two-step strategy before the bomb.

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