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Hiroshima: United States drops atomic bomb

With a blinding flash and a sky-high fireball, the world's first atomic bomb exploded over the Japanese city of Hiroshima on Aug. 6, 1945. The American bomb killed about 70,000 Japanese instantly, and an equal number would soon die of radiation poisoning. The weapon saved American soldiers' lives and ended the Second World War, but it ushered in a new era of nuclear arms. CBC Archives looks at the atomic bomb, its impact on Hiroshima and its legacy.

On Aug. 6, 1945, at 8:15 in the morning, the world changes forever. The United States has unleashed the atomic bomb on Hiroshima, a Japanese city of 350,000. In a radio speech announcing the bombing, U.S. President Harry Truman says Hiroshima was chosen because it is a military base, and the United States wishes to avoid killing civilians. The CBC Radio program Playback rebroadcasts Truman's speech.

"Having found the atomic bomb, we have used it," says Truman. "We have used it against those who attacked us without warning at Pearl Harbor." The president says the bomb will save thousands of American lives, and he warns that the United States will use it again until Japan's ability to make war is completely destroyed: "Only a Japanese surrender will stop us." 
• On Dec. 7, 1941, Japanese warplanes launched a surprise attack on an American naval base at Pearl Harbor in the Hawaiian Islands. The attack prompted the United States, which had previously been neutral, to declare war on Japan and enter the Second World War.
• In a speech the following day denouncing the Pearl Harbor attack, President Franklin Roosevelt described Dec. 7, 1941, as "a date which will live in infamy."

• The Japanese were a formidable enemy. By mid-1945, American attacks on the Japanese islands of Iwo Jima, Okinawa and others had produced heavy casualties for both sides.
• One U.S. general estimated that in a mainland invasion, using conventional weapons, Americans could expect 500,000 casualties.
• The term "casualties" refers to men lost to the military forces due to death, injury or being taken prisoner of war.

• The atomic bomb was literally the United States' secret weapon. On July 26, 1945, just 10 days after the successful Trinity test, U.S. President Harry Truman wrote a surrender ultimatum to the Japanese. The demand did not mention a new weapon, but threatened "prompt and utter destruction" if the Japanese did not surrender.

• The United States identified several criteria while deciding upon which Japanese city to drop the atom bomb. To accurately gauge the bomb's effects, it had to be a city that had not already experienced extensive bombing. That ruled out Tokyo, the capital.
• Kyoto was an early candidate because it was a historically significant city that was psychologically important to the Japanese. Yokohama, Hiroshima and Nagasaki were later added to a list of 17 potential targets.

• U.S. Defence Secretary Henry Stimson rejected Kyoto as a choice. He had visited the city three times in the 1920s and been impressed by its ancient culture. Bombing it, he said, would reduce America's postwar stature.
• Hiroshima, because of its size and its designation as a military city, became the default target. Factories in the city produced war materials and 25,000 troops were stationed there.


• Hiroshima was the seventh-largest city in Japan.
• The atomic bomb was dropped by the Enola Gay, a B-29 bomber named after the mother of its pilot, Paul Tibbets.
• Both plane and pilot were part of the 509th Composite Group, a squadron based on the Pacific island of Tinian.

• The uranium bomb that was dropped on Hiroshima was code-named "Little Boy."
• The total cost of the United States' atomic bomb development program was $2 billion US ($21 billion in 2005 dollars). When the uranium for Little Boy was delivered to Tinian, the chief scientist on the island signed a receipt for it. He calculated its approximate value at half a billion dollars.

• On Aug. 9, 1945, a second bomb, "Fat Man," was dropped on the Japanese city of Nagasaki. Fat Man was a plutonium bomb — the same type that had been tested in New Mexico.
• Canadian serviceman John Ford, who was held in a prisoner of war camp near Nagasaki, witnessed the explosion. See a clip in which Ford describes what he witnessed that day.

• Also on Aug. 9, the Soviets invaded Manchuria, a Japanese-occupied region in the northeast of China.
• On Aug. 15, 1945, Japan officially announced it would agree to the Allied terms of surrender. The official surrender document was signed on Sept. 2 that year aboard the U.S. battleship Missouri.
• Both days (Aug. 15 and Sept. 2) came to known as VJ-Day (Victory in Japan). The day of surrender is marked on Aug. 14 in Japan.
Medium: Radio
Program: Playback
Broadcast Date: March 17, 1969
Guest(s): Harry S. Truman
Duration: 1:12

Last updated: June 18, 2013

Page consulted on February 13, 2014

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