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The United States’ Use Of Nuclear Weapons 77 Years Ago Was A Moral And Strategic Imperative

Americans are no strangers to “times that try men’s souls,” to borrow a phrase from Thomas Paine. By mid-1945, the United States had been at war for three-and-a-half years, enduring the draft, separation from loved ones, mounting numbers of casualties, and rationing, with no end in sight. Many Americans were weary, not unlike our feelings now, after two-and-a-half years of privations and anguish related to the COVID-19 pandemic.

That sense of anxiety and the widespread desire to return to normality brought to mind how World War II was suddenly – and to many, unexpectedly – resolved. Saturday, Aug. 6, marks one of the United States’ most important anniversaries, memorable not only for what happened on this date in 1945 but for what did not happen.

What did happen was that the Enola Gay, an American B-29 Superfortress bomber, dropped Little Boy, a uranium-based atomic bomb, on the Japanese city of Hiroshima. That historic act hastened the end of World War II, which concluded within a week after the Aug. 9 detonation of Fat Man, a plutonium-based bomb, over Nagasaki.

They were the only two nuclear weapons ever used in warfare.

I have two peripheral connections to those events. The first is that when Little Boy was dropped on Hiroshima, my father, a staff sergeant in the U.S. Army infantry who had fought in the Italian campaigns of WWII, was on a troopship, expecting to be deployed to the Pacific theater of operations. (The European Axis powers had surrendered three months earlier.)  Neither he nor his fellow soldiers relished the prospect of participating in the impending invasion of the Japanese main islands. When the Japanese surrendered on Aug. 14, the ship headed, instead, for Virginia, where the division was disbanded. Dad headed home to Philadelphia, and I was born two years later.

My second connection was that during the 1960s, three of my M.I.T. physics professors had participated three decades earlier in the Manhattan Project, the military research program that developed the atomic bombs during the war. In class, one of these professors recalled that, after the first test explosion (code-named “Trinity”), he was assigned to drive Maj. Gen. Leslie Groves, the director of the project, to view the result. They arrived to find a crater 1,000 feet in diameter, and 6 feet deep, with the desert sand inside turned into glass by the intense heat. Groves’ response was, “Is that all?”

Approximately 66,000 are thought to have died in Hiroshima from the acute effects of the Little Boy bomb, and about 39,000 in Nagasaki from the Fat Man device. In addition, there was a significant subsequent death toll due to the effects of radiation and wounds.

Shortly thereafter, the “Was it really necessary?” questions began. The Monday-morning quarterbacks started to question the morality and military necessity of using nuclear weapons on Japanese cities. Even nuclear physicist Leo Szilard, who in 1939 had composed the letter for Albert Einstein‘s signature that resulted in the formation of the Manhattan Project, characterized the use of the bombs as “one of the greatest blunders of history.” Since then, there have been similar periodic eruptions of revisionism, uninformed speculation, political correctness, and historical amnesia.

The historical context and military realities of 1945 are often forgotten when judging whether it was “necessary” for the United States to use nuclear weapons. The Japanese had been the aggressors, launching the war with a sneak attack on Pearl Harbor in 1941, and systematically and flagrantly violating various international agreements and norms by employing biological and chemical warfare, the torture and murder of prisoners of war, and the brutalization of civilians, including forcing them into prostitution and slave labor.

But leaving aside whether our enemy “deserved” to be attacked with the most fearsome weapons ever employed, skeptics are also quick to overlook the “humanitarian” and strategic aspects of the decision to use them.

Operation Downfall Meets A Fork In The Road

As a result of the bombing of Hiroshima and Nagasaki, what did not need to happen was “Operation Downfall” – the massive Allied (largely American) invasion of the Japanese home islands that was being actively and meticulously planned. As Allied forces closed in on the main islands, the strategies of Japan’s senior military leaders ranged from “fighting to the last man” to inflicting heavy enough losses on invading American ground forces that the United States would be forced to agree to a conditional peace. Operation Downfall was being pursued primarily because U.S. strategists knew (from having broken the Japanese military and diplomatic codes) that there was virtually no inclination on the part of the Japanese to surrender unconditionally.

Lastly, because the Allied military planners assumed that “operations in this area will be opposed not only by the available organized military forces of the Empire (of Japan), but also by a fanatically hostile population,” astronomical casualties on both sides were thought to be inevitable. The losses between February and June 1945, just from the Allied invasions of the Japanese-held islands of Iwo Jima and Okinawa, were staggering: a total of 18,000 dead and 78,000 wounded. That harrowing experience was accounted for in the planning for the final invasion.

As I discussed this retrospective with a friend who is a retired Marine four-star general, he told me this: “[F]ollowing Okinawa and Iwo Jima, all six Marine divisions were being refitted for the attack on the home islands. None of the divisions had post-assault missions, because the casualty estimates were so high that they would initially be combat inoperable until they were again remanned and refitted. Basically, the Marines were to land six divisions abreast on Honshu, then the Army would pass through for the big fight on the plains inland.” (Note: a division has approximately 23,000 Marines.)

The general continued: “What made this different was, unlike the Pacific campaign to date other than Guadalcanal back in 1942, this would be the first time the Japanese could reinforce their units. After Guadalcanal, in the fights across the ocean, the U.S. Navy isolated the objectives so the Japanese could not reinforce. The home islands would be a different sort of fight, hence the anticipated heavy casualties.”

A study performed by physicist (and future Nobel Laureate) William Shockley for the War Department in 1945 estimated that the invasion of Japan would have cost 1.7-4 million American casualties, including 400,000-800,000 fatalities, and between 5 and 10 million Japanese deaths.

These fatality estimates were, of course, in addition to the members of the military who had already perished during almost four long years of war; American deaths were already about 292,000. The implications of those numbers are staggering: The invasion of Japan could have resulted in the death of more than twice as many Americans as had already been killed in the European and Pacific theaters of WWII up to that time!

The legacy of Little Boy and Big Man was in reshaping the course of history: A swift end to the war made Operation Downfall unnecessary and, thereby, prevented millions of deaths.

Mounting Casualties, Both Non-Military And Military Alike

During the years since WWII, much has been made of the moral boundary that was breached by the use of nuclear weapons, but many military historians regard as far more significant the decisions earlier in the war to adopt widespread urban bombing of civilians. This threshold was initially transgressed by Hitler, who attacked English cities in 1940 and 1941; and the practice was later adopted by the Allied forces, which resulted in the devastation of major cities such as Dresden, Hamburg, and Tokyo.

Previously, the bombing had been focused primarily on military objectives, such as airfields, munitions factories, and oil fields; or on critical transportation links, such as train stations and tracks, bridges, and highways. Never before, on such a scale, had non-military targets been targeted in order to degrade the morale of the populace. In one instance, over 100,000 were killed in a single night of firebombing of Tokyo, March 9-10, 1945. (The figures are imprecise, because many bodies were incinerated and never recovered.) More than 22,000 died in Dresden, February 13-15, 1945, and about 20,000 in Hamburg, July, 1943.

In an email to me, my former colleague historian Victor Davis Hanson called attention to two factors that made the case for the use of America’s nuclear weapons. First, “thousands of Asians and allied prisoners were dying daily throughout the still-occupied Japanese Empire, and would do so as long as Japan was able to pursue the war.” Second, Maj. Gen. Curtis LeMay, who was in charge of all strategic air operations against the Japanese home islands “planned to move forces from the Marianas to newly conquered and much closer Okinawa, and the B-29 bombers, likely augmented by European bomber transfers after V-E Day, would have created a gargantuan fire-bombing air force that, with short-distance missions, would have done far more damage than the two nuclear bombs.”

In fact, the most destructive bombing raid of the war, and in the history of warfare, was the nighttime fire-bombing of Tokyo on March 9-10, 1945. In a three-hour period, the main bombing force dropped 1,665 tons of incendiary bombs, which caused a firestorm that not only killed some 100,000 civilians, but also destroyed a quarter of a million buildings and incinerated 16 square miles of the city. Tokyo was not the only target: By the end of the war, incendiaries dropped by LeMay’s bombers had totally or partially consumed 63 Japanese cities, killing half a million people and leaving eight million homeless.

The WWII casualty statistics are numbing, and bring to mind a saying often attributed to Joseph Stalin: a single death is a tragedy, a million deaths is a statistic.

During World War I, Europe lost most of an entire generation of young men; combatant fatalities alone were approximately 13 million. Memories of that calamity were still fresh three decades later. In 1945, as they deliberated, Allied military planners and political leaders were correct, both strategically and morally, in not wanting to repeat that history. (And President Harry Truman, who had succeeded Franklin D. Roosevelt upon the latter’s death only four months earlier, would not have wanted his legacy to include causing the unnecessary death of hundreds of thousands of American servicemen.) It was their duty to weigh carefully the costs and benefits for the American people, present and future. Had they been less wise or courageous, my generation of post-war Baby Boomers would have been much smaller.

These kinds of decisions are truly the stuff of history, writ large, but governments perform such balancing acts all the time. We are seeing that today in the creation of policies to manage the COVID-19 pandemic. How, for example, do we balance the very real, and high, costs of lockdowns – businesses obliterated, livelihoods lost, children deprived of education and social stimuli – against increasing numbers of deaths, the persistent, debilitating, post-“recovery” effects of infections, the stresses on our health care system, and other spinoff impacts on health from COVID-19 infections, if we are too timid with mask and vaccine mandates?

As Truman found in deciding whether to use Little Boy and Fat Man, sometimes you need to choose the least bad of the alternatives. And to arrive at that, you need to value data and expert analysis over ideology, politics, or vox populi.

I pity the decision-makers.

Henry I. Miller, a physician and molecular biologist, was a research associate at the National Institutes of Health and the founding director of the FDA’s Office of Biotechnology. You can find him online or on Twitter at @henryimiller, and read more of his writing at

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  • It is a little-known fact that the USA had a Top Secret plan to make a new atomic bomb ‘every ten days’ in 1945. Two days before the Japanese surrender, on August 13, 1945, aides to the US Chief of Staff and the military commander of the Manhattan Project discussed the tactical use of A-bombs for the invasion of Japan. A third A-bomb was ready to be used on August 19. Seven more would be ready by November 1, 1945, the planned date for the invasion of Kyushu.

    And what would be ready after that? The chilling answer was that the US could make a new A-bomb “Every ten days.” By March 1, 1946, the planning date to invade Honshu, a total of 22 A-bombs would have been used or ready to be used, including the two that were actually dropped.

    More details, including a transcript of the phone call between these two aides, are available at:

  • In my opinion, we are doing the same thing now as we did then, in that we are using current knowledge (of what happened back then (and how we view it), and our current tastes in morality
    to judge what was done in the past.
    Also, as Dr. Miller points out, many American children would not have been born. And those who had been born would grow up without a parent, which might have traumatically affected their childhood to their detriment (and ours if an anti-social criminal had been generated because of this).
    It is easy and convenient to make a judgement on past behavior-whether it is slavery (not its historical accuracy), or the bombing of Japan. It is also terribly arrogant and presumptious.

  • Only 3 weeks from Trinity being tested to Hiroshima. Doesn’t seem odd? Does to me. No mention at all of Russian forces either. Weird.

    • Why odd? The Trinity device and Hiroshima bomb were different devices — one employing Plutonium and the other U235, respectively. The U235 device had none of the nuclear complications of the Plutonium bomb and was considered so reliable, it was never even tested ahead of time.

      • The ‘Russians’ advancement is often cited as reason the Japs were about to surrender! I’ve read enough about the Japs defense plans for the main island to know that’s rubbish. But heh we have people arguing about the Founding Fathers intentions….while completely ignoring who Robert Byrd was

  • My dad was a B-24 Liberator crewmember and his brother, my uncle, a B-24 pilot in Europe. I fought in Vietnam. I am also a writer and have written several articles on the decision to drop the A-bomb and the upcoming invasion of Japan. First, I doubt the author’s claim that his father’s troopship was bound for the Pacific. Soldiers weren’t told where they were going so they probably assumed they were on the way to the Pacific. In fact, the military was already demobilizing the men who fought in Europe. My own father was demobilized a few days after the A-bomb was dropped.

    It is a myth that the bombs “ended the war.” In fact, the Japanese did not surrender until Harry Truman, who didn’t know diddly about the bombs, sent a backdoor message to Tokyo promising that the emperor would be allowed to remain on the throne. Only then did Japan agree to surrender. Furthermore, Japanese on Kyushu had been putting out white flags for several days to Fifth Air Force fighter/bombers and light and medium bombers wouldn’t attack them. After the war, Japanese generals responsible for Kyushu were interviewed by MacArthur’s intelligence and the report was classified for 50 years. Since it’s release, authors leave out the part where they relate that they had a very small force of Kamikazes because it contradicts claims made on the basis of an overly ambitious plan the Japanese had to defend the home islands. Read the report at The reality is that Truman rushed to drop the bomb to demonstrate it to the Soviets (who already knew about it) before Japan surrendered.

    • Two very good books about this very topic are “The Fleet at Flood Tide: America at Total War in the Pacific, 1944-1945” by James D. Hornfischer and “The Fall of Japan: The Final Weeks of World War II in the Pacific” by William J. Craig. The Americans knew from the battles closer to the Japanese home islands (Saipan, Okinawa, Iwo Jima) that they were fighting a suicide-death cult. The Japanese military brain-washed island civilians everywhere they went – thus the reason the civilians committed suicide on Saipan by leaping off cliffs. The militarists in Jpn wanted to continue fighting after the 1st atomic bomb, & even after the 2nd bomb was dropped. They still didn’t surrender immediately after the 2nd bomb. There were multiple coup attempts by the militarists to prevent surrender. It was only the involvement of the emperor (who America permitted to remain in power) who ultimately drove them to unconditional surrender, knowing, if they did not surrender, more bobms like Little Boy & Fat Man were en route.

  • Contrary to one other post in here, I believe that at least many of the GIs embarking over the Pacific had a very good idea that they were to be part of the invasion force. Two of my uncles were on ships headed there and they later said, after the invasion was called off, that they believed the A-bombs might have saved their lives. At least one of them told the family, after the war, that they all knew where they were headed and they all knew it was going to real bloody and were forever grateful that Truman decided to drop those bombs. I’m sure their wives and the children they would beget were grateful too.
    Can anyone imagine if Hitler or Japan had gotten the atomic bomb first? Seems almost providential, doesn’t it?

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