Atomic Bombing of Hiroshima
The United States dropped the first atomic bomb used in warfare on the Japanese city of Hiroshima.
Where this fits on the timeline. By the summer of 1945, World War II was nearly over. Germany had surrendered in May, but Japan fought on, and the fighting in the Pacific had grown horrifically bloody. Then, in the space of three days in August, two American atomic bombs destroyed two Japanese cities, Japan surrendered, and the world crossed into the nuclear age. The bombing of Hiroshima on August 6, 1945, is one of the most consequential, and most fiercely debated, events in human history.
A secret weapon and a brutal war
Two things came together in 1945. The first was the Manhattan Project, a vast, top-secret American program that had spent years and billions of dollars racing to build an atomic bomb, led by scientists at Los Alamos, New Mexico. On July 16, 1945, they tested the first nuclear device in the New Mexico desert, and it worked. The second was the shape of the Pacific war. The battles for Iwo Jima and Okinawa earlier in 1945 had been appallingly costly for both sides, and American planners feared that invading Japan's home islands would cost hundreds of thousands more lives. In late July the Allies issued the Potsdam Declaration, demanding Japan's unconditional surrender or 'prompt and utter destruction.' Japan's government did not accept it. President Harry S. Truman, who had learned the bomb even existed only after becoming president that April, gave the order to use it.
August 6, 1945
Eight-fifteen in the morning. A B-29 bomber named the Enola Gay, piloted by Colonel Paul Tibbets, flew over Hiroshima and released a uranium bomb nicknamed 'Little Boy.' It detonated roughly 1,900 feet above the city at about 8:15 a.m., with the force of some 15,000 tons of TNT. In an instant a blinding fireball hotter than the surface of the sun seared the city; the blast and the firestorm that followed flattened nearly everything within about a mile and a half. Hiroshima, a city of several hundred thousand people that morning, was largely destroyed by a single bomb dropped from a single plane.
The human cost
Behind the numbers were people. The death toll at Hiroshima is difficult to count and is always given as an estimate. Roughly 70,000 to 80,000 people were killed almost instantly, most of them civilians, and by the end of 1945 the total had risen to about 140,000 as people died of burns, injuries, and a new and terrible affliction, radiation sickness. Survivors, known in Japan as hibakusha, or 'people affected by the bomb,' suffered burns and, in the years that followed, higher rates of leukemia and other cancers. Their testimony has become one of the world's most powerful warnings about nuclear weapons. These figures are estimates that differ across sources, because so many records and lives were destroyed at once.
Nagasaki and Japan's surrender
Three days later, and then the end. On August 8 the Soviet Union declared war on Japan and invaded Japanese-held Manchuria. The next day, August 9, a second American bomb, a plutonium weapon called 'Fat Man,' destroyed the city of Nagasaki, killing tens of thousands more. Facing atomic attack from the United States and invasion from the Soviet Union, Emperor Hirohito's government gave in. Japan announced its surrender on August 15, 1945, and signed the formal documents aboard the USS Missouri on September 2, 1945, bringing World War II to an end.
A debate that continues
Historians still argue about this, and students should understand why. Supporters of the decision argue that the bombs ended the war quickly and prevented a full-scale invasion of Japan that could have cost enormous numbers of American and Japanese lives, given how bloody Iwo Jima and Okinawa had been. Critics argue that the massive civilian death toll was not justified, that Japan was already near defeat with its navy and air force shattered, and that the Soviet entry into the war, a demonstration of the bomb, or modified surrender terms might have ended the fighting without destroying two cities. This is a genuine and unresolved ethical debate, and thoughtful people disagree; the goal in studying it is to understand the arguments on both sides, not to memorize a single verdict.
The nuclear age
A door that could not be closed. Hiroshima and Nagasaki are the first, and so far the only, times nuclear weapons have been used in war. They opened the nuclear age and helped set off the arms race between the United States and the Soviet Union that would define the Cold War. In Hiroshima, the skeletal ruin of one building near the blast's center was preserved as the Atomic Bomb Dome, now part of the Hiroshima Peace Memorial and a UNESCO World Heritage Site, standing as a plea that such weapons never be used again.
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Key Takeaways
On August 6, 1945, the U.S. dropped the first atomic bomb used in war on Hiroshima, Japan
The bomb, "Little Boy," was built by the secret Manhattan Project and dropped from the B-29 Enola Gay
About 70,000–80,000 people died almost instantly; the toll reached roughly 140,000 by the end of 1945 (figures are estimates)
A second bomb destroyed Nagasaki on August 9, and Japan announced its surrender on August 15, 1945
Historians still debate whether the bombings were necessary or justified, and the arguments on both sides matter
The bombings opened the nuclear age and the Cold War arms race; the Atomic Bomb Dome memorializes the victims