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The Month That Changed The World: 1945, 75 Years Ago

[Revised and updated repost of 2016 essay]

From “Trinity” to V-J Day

The Month That Changed the World


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The Atomic Bomb Dome-Hiroshima (Photo Courtesy of Hiroshima and Nagasaki Remembered)

 On August 6, 1945, the New York Times asked:

“What is this terrible new weapon?”

(New York Times, August 6, 1945: “First Atomic Bomb Dropped on Japan”)

The story followed the announcement made by President Harry S. Truman:

“SIXTEEN HOURS AGO an American airplane dropped one bomb on Hiroshima, an important Japanese Army base. That bomb had more power than 20,000 tons of T.N.T. It had more than two thousand times the blast power of the British ‘Grand Slam’ which is the largest bomb ever yet used in the history of warfare.”

August 6, 1945

President Harry S. Truman (Photo: Truman Library)

President Harry S. Truman
(Photo: Truman Library)

(“Statement by the President Announcing the Use of the A-Bomb at Hiroshima”: Truman Library and Museum)

The first atomic device was exploded in the “Trinity” test at Alamogordo, New Mexico, on July 16, 1945. Read this excellent account of the test in National Geographic.

In the course of the next weeks, the world would be transformed, with the arrival of the Atomic Age, Japan’s surrender, the end of World War II, the charter of the United Nations, and the beginning of the Cold War.

President Truman had taken office upon the death of President Roosevelt on April 12 without knowledge of the Manhattan Project or the atomic bomb’s existence. After he was told about the potential weapon, he was informed of the success of the Trinity test while at a meeting with Churchill and Soviet Union leader Joseph Stalin in Potsdam, a city in defeated Germany. On July 17, Truman came face to face with the Soviet dictator.

“I told Stalin that I am no diplomat but usually said yes or no to questions after hearing all the argument.”

–Read Post on Potsdam and Truman meeting Stalin.

Following the successful Trinity test, the components of the atomic bomb were loaded on the USS Indianapolis and transported to an airbase on Tinian Island in the Pacific. Many of the crew of nearly 1,200 men had no idea what the ship was carrying.

On Jul7 24, Truman informed Stalin of a “new weapon of unusual destructive force.” But Stalin already know about the atomic bomb because of a network of spies.

Prime Minister Winston Churchill was defeated in the general election on July 26, and replaced by Clement Attlee as Prime Minister.

“The landslide victory comes as a major shock to the Conservatives following Mr Churchill’s hugely successful term as Britain’s war-time coalition leader, during which he mobilised and inspired courage in an entire nation.”


At the Potsdam Conference, the Potsdam Declaration demanded Japan’s “Unconditional surrender” on July 26. The Indianapolis reached Tinian that day.

USS Indianapolis 10 July 1945, after final overhaul and repair of combat damage. Photograph from the Bureau of Ships Collection in the U.S. National Archives (Naval History and Heritage Command

“Indianapolis departed San Francisco on 16 July 1945, foregoing her post-repair shakedown period. Touching at Pearl Harbor on 19 July, she raced on unescorted and reached Tinian on 26 July, covering some 5,000 miles from San Francisco in only ten days.

After the delivery of the atomic bomb components, the ship sailed for Guam and the Philippines. On July 30, the ship was torpedoed by a Japanese submarine and sank in twelve minutes.

“What followed was an ordeal of hell on earth for those who survived the sinking. For a whole host of reasons, many related to the secrecy of her atom bomb mission, the rest of the Navy did not know that Indianapolis was missing.”

— Sam Cox (Rear Adm., USN, Ret.), “Lest We Forget: USS Indianapolis and her sailors”

The Japanese government rejected the surrender demand on July 29.  The assembly of the atomic bomb, nicknamed “Little Boy,” was completed on July 31.

In Potsdam, President Truman was notified of the bomb being ready. He wrote a message that concluded:

“Release when ready, but not sooner than August 2. HST”

According to the Truman Library:

The actual reply that President Truman wrote on July 31, 1945 (Photo taken by Dawn Wilson at the Harry S. Truman Presidential Library)

“No known written record exists in which Harry Truman explicitly ordered the use of atomic weapons against Japan. The closest thing to such a document is this handwritten order, addressed to Secretary of War Henry Stimson, in which Truman authorized the release of a public statement about the use of the bomb. It was written on July 31, 1945 while Truman was attending the Potsdam Conference in Germany. In effect, this served as final authorization for the employment of the atomic bomb, though the expression ‘release when ready’ refers to the public statement.”

Source: Truman Library

On August 1, 1945, the atomic bomb was ready and flight orders were prepared. But weather delayed the mission. Of four potential target cities, Hiroshima was chosen as the primary target.

In Potsdam that day, the Big Three were wrapping up their meetings and discussed plans for the  trials of war criminals that later become known as the Nuremberg Trials.

In the Pacific, hundreds of survivors from the Indianapolis were desperately trying to stay afloat in the shark-infested waters.

“In that clear water you could see the sharks circling. Then every now and then, like lightning, one would come straight up and take a sailor and take him straight down.” – Survivor the Indianapolis sinking to the BBC.

The U.S. Navy was still unaware that the ship had gone down. About 800 men had gone into the water and the survivors were spotted by a reconnaissance plane four days after the sinking; 317 survivors were rescued on August 2.

The Big Three at the end of the Potsdam Conference: Front row (Left to Right) Prime Minister Attlee, President Truman, Generalissimo Stalin. Source: Army Signal Corps Collection in the U.S. National Archives.

Shortly after midnight, the Potsdam Conference concluded that day with a joint communique. It included reference to the United Nations, whose organization and charter had been completed on June 26 at a conference in San Francisco Although Truman mentioned a future Washington meeting, he and Stalin never met again. What was clear was that the Conference had solidified the Soviet Union’s domination over much of Eastern Europe, including the eastern half of a divided Germany. Admiral William D. Leahy, Truman’s Chief of Staff, later wrote:

“The Soviet Union emerged at this time as the unquestioned all-powerful influence in Europe….”

On August 6, 1945, the first atomic bomb was detonated over Hiroshima.

“In less than one second, the fireball had expanded to 900 feet. The blast wave shattered windows for a distance of ten miles and was felt as far away as 37 miles. Over two-thirds of Hiroshima’s buildings were demolished. The hundreds of fires, ignited by the thermal pulse, combined to produce a firestorm that had incinerated everything within about 4.4 miles of ground zero.”

Source: Hiroshima and Nagasaki Remembered.

“In the street, the first thing he saw was a squad of soldiers who had been burrowing into the hillside opposite, making one of the thousands of dugouts in which the Japanese apparently intended to resist invasion, hill by hill, life for life; the soldiers were coming out of the hole, where they should have been safe, and blood was running from their heads, chests, and backs. They were silent and dazed.

Under what seemed to be a local dust cloud, the day grew darker and darker.”

–John Hersey, “Hiroshima,” New Yorker (August 24, 1946)

Fat Man being lowered and checked on transport dolly for airfield trip Image Source: Heritage Foundation

In Hiroshima, the estimated death toll was eighty thousand people killed instantly; as many as 90 percent of the city’s nurses and doctors also died instantly. By 1950, as many as 200,000 had died as a result of long-term effects of radiation.

On August 8, the Soviet Union declared war on Japan and invaded Manchuria the next day, sending more than one million troops into the Japanese-held territory.

Hours later on August 9, a second device, a plutonium bomb nicknamed “Fat Man,” was used against the city of Nagasaki.

The death toll in Nagasaki also reached 80,000 by the end of 1945.

Japan surrendered on August 14 (August 15 in Japan).


Truman announces Japan’s surrender to reporters in Oval Office.
Credit: Rowe, Abbie National Park Service Harry S. Truman Library & Museum.

Across America and England, jubilant crowds filled the streets once more, as they had in May 1945 after Germany’s surrender ended the war in Europe.

V-J Day Times Square August 14, 1945 Library of Congress Prints and Photographs Division. New York World-Telegram and the Sun Newspaper Photograph Collection.

On September 2, 1945, a formal surrender ceremony was performed in Tokyo Bay and that date is also referred to as VJ Day.

Almost since the day the first atomic bomb was dropped on Hiroshima, critics have second-guessed Truman’s decision and motives. A generation of historians have defended or repudiated the need for unleashing the atomic weapon. Admiral William D. Leahy, who was with Truman at Potsdam, later wrote in a memoir:

Once it had been tested, President Truman faced the decision as to whether to use it. He did not like the idea, but he was persuaded that it would shorten the war against Japan and save American lives. It is my opinion that the use of this barbarous weapon at Hiroshima and Nagasaki was of no material assistance in our war against Japan.

–William D. Leahy, I Was There (1950)

What history has confirmed is that some of the men who created the bomb didn’t understand how horrifying its capabilities were. Of course, they understood the destructive power of the bomb, but radiation’s dangers were far less understood. As author Peter Wyden tells it in Day One, an account of the making and dropping of the bomb, scientists involved in creating what they called “the gadget” believed that anyone who might be killed by radiation would die from falling bricks first.

But many historians contend that the United States was wary of Stalin and his designs on Japan’s wartime territory.  They argue that the use of the two devices was also meant as a signal to the Stalin and the Soviet Union –which had declared war on Japan and moved troops into Manchuria– that the United States possessed these weapons and was willing to use them. In other words, the dropping of the atomic bombs became the first volley in the Cold War.

August 6 and 9 should not be days to argue about the politics of the bomb. They should be days of solemn remembrance of the victims. And of contemplating the horrific power of the weapons we create.

The City of Hiroshima Peace Memorial Park and Museum offers an English language website with a history of Hiroshima and the effects of the bombing.

You can read more about Hiroshima and the dropping of the atomic bombs in Don’t Know Much About History and more about President Truman in Don’t Know Much About the American Presidents and in The Hidden History of America At War.


Don't Know Much About History (Revised, Expanded and Updated Edition)

Don’t Know Much About History (Revised, Expanded and Updated Edition)

Now In paperback THE HIDDEN HISTORY OF AMERICA AT WAR: Untold Tales from Yorktown to Fallujah

Now In paperback THE HIDDEN HISTORY OF AMERICA AT WAR: Untold Tales from Yorktown to Fallujah

Don't Know Much About® the American Presidents (Hyperion paperback-April 15, 2014)

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