By all accounts, the strategy achieved its goal. The destruction of Nagasaki and Hiroshima persuaded the Japanese war cabinet to accept the Allied terms of surrender, which they had rejected only weeks earlier. That decision–forced by the obliteration of two Japanese cities–saved millions of lives on both sides, helping pave the war for a peaceful occupation of Japan, and transformation of that nation into a liberal democracy.

But, as we noted on the Hiroshima anniversary earlier this week, Harry Truman’s decision to use atomic weapons has been discredited and demonized over the past seven decades. It was morally reprehensible, critics charge, and militarily unnecessary. Under the weight of a naval blockade and the continued fire-bombing of its cities, they argue, Japan would have surrendered in a matter of months, around the time of the scheduled invasion (1 November).

But many of those military forecasts were fatally optimistic. Japan had marshaled remaining reserves of gas, ammunition and personnel for a final, desperate defense of the home islands. The recently-completed Okinawa campaign had resulted in 72,000 Allied casualties (mostly American); projections for invasion of Japan suggested that more than 250,000 U.S. military personnel would be killed or wounded, with even higher casualties among Japanese civilians that would assist their army in defending the homeland.

As recounted in Richard Frank’s Downfall: The End of the Japanese Imperial Empire, the mission of Japan’s populace was foretold in the Imperial Headquarters’ war journal, which made it clear that all Japanese were expected to resist the invasion:

“We can no longer direct the war with any hope of success. The only course left is for Japan’s one hundred million people to sacrifice their lives by charging the enemy to make them lose the will to fight.

Such thoughts were echoed by General Anami Korechika, the hard-line Army Minister who observed:

“Even though we may have to eat grass, swallow dirt, and lie in the fields, we shall fight on to the bitter end, ever firm in our faith that we shall find life in death”

The prospect of fighting the entire population of Japan–on their home soil–led some American military leaders to reassess the invasion’s prospects for success. By August 1945, the Chief of Naval Operations, Admiral Ernest King, and the Pacific Fleet Commander, Admiral Chester Nimitz, expressed concerns that the planned invasion might end in a Japanese victory, allowing them to sue for peace on more favorable terms. By some estimates, the assault on Kyushu would result in 300,000 Americans killed, wounded or captured, a staggering toll for a nation anxious to see the war end.

Given those estimates, our ability to decisively defeat Japan in 1945–using conventional weapons–was far from assured. From a military perspective, Truman’s decision to use the atomic bomb was clearly justified. One Japanese official later described the attacks on Hiroshima and Nagasaki (and the concurrent Soviet invasion of Manchuria), as “gifts from the gods,” allowing the war to end quickly, and without an invasion of the home islands.

The morality of Truman’s choice is more problematic, at least in the minds of many liberals. In today’s Washington Post, novelist Nora Gallagher muses on “The Soul of the Destroying Nation,” a title taken from Gandhi’s observation about the atomic bombing of Hiroshima and Nagasaki. He said that the attacks “resulted for the time being in destroying the soul of Japan. What has happened to the soul of the destroying nation is yet too early to see.”

Ms. Gallagher reports that she has been mulling over that question since completing her latest novel Changing Light, set against the backdrop of the Manhattan Project, and the dawn of the nuclear age. From her perspective, the U.S. changed–and for the worse–when we dropped the bombs on Hiroshima and Nagasaki:

What has happened to the soul of the destroying nation?

What happened to us as a nation on August 6, 1945? Did the use of a weapon designed to ruthlessly annihilate whole cities contribute to where we find ourselves today? How did Hiroshima erode our sense of morality, what we permit ourselves as a nation to do? How did it affect our fragile sense of what is permissible for one human being to do to another? Finally, what is the connection between Hiroshima and Guantanamo, Hiroshima and Abu Ghraib?

What has happened, indeed?

Well, the nation that developed the atomic bomb–and used it to end the most destructive war in history–remains the global champion for freedom and liberty. The United States that helped transform defeated foes into democratic allies is the same nation that led the fight against Soviet communism, and eventually defeated that threat as well. Hundreds of millions of people across Europe and Asia owe their liberty (directly or indirectly) to a nation that ushered in the nuclear era, and used those same weapons to keep the peace for more than 60 years. It’s the same nation that returned from World War II and established a more prosperous, just and equitable society for all its citizens. America is far from perfect, but I’d say our collective soul is in pretty good shape.

Ms. Gallagher sees only senseless slaughter at Hiroshima and Nagasaki, agonizing over the innocents who died in both cities. But was suffering unique to the civilian population of Japan? Hardly. Most of the British who died in The Blitz were civilians. The same holds true among residents of Hamburg and Dresden, devastated by Allied fire raids in 1943 and 1945, respectively. And, lest we forget, the combined casualties of Hiroshima and Nagasaki are roughly equal to those inflicted during the Rape of Nanking, perpetuated by the forces of Imperial Japan.

Revisionists like Ms. Gallagher prefer to view the atomic bombings as isolated, horrific events, outside the prism of a global war and President Truman’s determination to end it, once and for all. In that wider context, Mr. Truman faced the most difficult of moral dilemmas–unleashing atom bombs that would kill thousands, in the hope of saving millions; civilian and soldier, friend and foe alike.

Militarily and morally, history records that Harry Truman made the right decision, reflecting a national soul that is rooted in freedom, not destruction. And finally, to answer Ms. Gallagher’s question, the only “connection” between Hiroshima, Nagasaki and Guantanamo lies in the shared determination to defeat our enemies, save innocent lives, and defend freedom.

Harry Truman understood that. Nora Gallagher clearly doesn’t.