On August 6, 1945, the Enola Gay dropped the first atomic bomb used in warfare on Hiroshima, Japan, killing at least 80,000 people instantly.

The atomic bombs dropped on Japan had massive human costs

The US atomic bombings of Hiroshima and Nagasaki in August 1945 killed around 210,000 people—more than 38,000 of them estimated to be children—with tens of thousands more later dying from radiation-linked illnesses, leaving lifelong trauma and increased cancer risks.

The death toll of the atomic bombings in Japan remains disputed, with estimates ranging from 110,000 to 210,000.

Nine eyewitness accounts of Hiroshima and Nagasaki survivors

Japan's Hiroshima and Nagasaki became the first cities in history to be hit with nuclear weapons, where tens of thousands of civilians were killed nearly instantly. Hundreds of thousands of people who survived the bombings—referred to as hibakusha—dealt with wounds, radiation poisoning, and alienation from a society unable to process what had happened. This collection of accounts lets nine of those survivors speak, including one of the 165 survivors of both bombings.

Okinawa’s ferocity convinced the US atomic bombs was necessary

The brutal 82-day Battle of Okinawa—where US forces suffered nearly 50,000 casualties and Japanese military and civilians lost over 200,000 lives—clinched the grim reality that a full invasion of Japan would be even bloodier. This stark lesson directly shaped American decisions to deploy atomic weapons, aiming to avoid a potentially catastrophic ground war on the Japanese mainland.

The H-bomb is hundreds of times more powerful than the bomb dropped on Hiroshima

Unlike the atomic bombs dropped on Hiroshima, which relied on nuclear fission, the hydrogen bomb uses fusion to unleash vastly greater destructive power. Developed by both superpowers in the 1950s, it gave each the ability to destroy entire cities in seconds.

Oppenheimer reflected on the atomic bomb's legacy two decades later

In a 1965 CBS interview, J. Robert Oppenheimer discussed his role as Los Alamos director, expressing deeply mixed feelings about Hiroshima and Nagasaki and reflecting on how nuclear weapons had transformed the world since their first use.

A list of reasons against dropping the bomb on Japan

One of the perennial moral debates, the dropping of nuclear bombs on Japanese cities prompted strong, polarizing reactions at the time. This article breaks down one side of the argument: that the bomb was designed for defense, using it was illegal and racist, and that there were alternatives.

The Manhattan Project, the top-secret American program that built the world's first atomic bomb, cost $27B in today's dollars and reshaped global power.

The formal Japanese unconditional surrender that ended World War II took place on the deck of the USS Missouri in Tokyo Bay on Sept. 2, 1945.

Learn how Japan used the jet stream to launch attacks on US soil during World War II

In the final two years of the war, over 9,000 Fu-Go balloon bombs were launched from Japan, with about a thousand estimated to have reached North America. Six civilians killed by a Fu-Go bomb in Bly, Oregon, on May 5, 1945, became the only known deaths on American soil by enemy action during the war.

John Hersey’s ‘Hiroshima’ focused on the stories of atomic bomb victims

The nonfiction book is considered one of the earliest pieces of New Journalism and an arresting case against nuclear warfare. Describing the pain, wounds and trauma of six ordinary citizens, “Hiroshima” played a powerful role in American perception of the war by focusing on its human toll.

A single bomb on the USS Arizona killed 1,177 crew members in seconds

When a Japanese armor-piercing bomb triggered the explosion of the USS Arizona’s forward magazine during the attack, the blast killed 1,177 crew members within moments—accounting for nearly half of all American deaths at Pearl Harbor.

Cold War nuclear tests exposed thousands to atomic blasts

After World War II, nuclear powers conducted thousands of weapons tests. This video pairs archival footage with interviews of veterans who witnessed Pacific test explosions, capturing the scale, shock, and human experience of being near a nuclear detonation.

The Manhattan Project operated at three key sites, each with a distinct role in building the first atomic bomb.

Interviews from the Manhattan Project

This is an archive of interviews with people who worked on and were impacted by the Manhattan Project, the World War II-era effort that resulted in the atomic bomb. Listen to the "father of the atomic bomb," Julius Robert Oppenheimer, describe his daily routine during the project, which he reports officially started Dec. 6, 1941. This archive also includes interviews with survivors of the Hiroshima and Nagasaki bombings.

Building the first atomic bomb required unprecedented coordination

Creating the first atomic bombs demanded breakthroughs in physics, engineering, and logistics—uniting elite scientists with tens of thousands of workers across the US. This in-depth history explains how the Manhattan Project overcame those challenges.

The story of the Manhattan Project's unused demon core

A 3-inch, 14-pound sphere of nuclear reactive plutonium-gallium was set to be delivered to the Pacific Theater in 1945 to become the third atomic bomb dropped over Japan. When Japan surrendered, it was returned to Los Alamos in New Mexico for experiment, where two scientists would die testing whether the core could reach criticality—where it would release intense energy—via the use of a dense reflector. Watch the story here.

Hiroshimaites are glass-like spheres of fallout debris found in Hiroshima, where conditions created by the atomic bomb forged a previously unknown metal alloy with a unique crystal structure.

Robert Oppenheimer became the face of the Manhattan Project and the atomic bomb

This feature explores Oppenheimer’s early life, the traits that made him central to the development of the atomic bomb, and how his later years were marked by tension between pride in his work and opposition to weapons of mass destruction.

The Manhattan Project was one of the most expensive undertakings of World War II

Building the first atomic weapons required hundreds of thousands of workers, vast secret facilities, and enormous spending. This 1998 study details the full cost of the Manhattan Project and compares it to other major US wartime expenditures.

In 1962, the US detonated a nuclear weapon in space, which produced an electromagnetic pulse that disabled three low Earth orbit satellites and damaged electrical equipment in Hawaii.

Kurt Vonnegut's 'Cat's Cradle' was inspired by the bombing of Hiroshima

The writer fought in World War II and witnessed the firebombing of Dresden, which he recounted in 1969's satirical "Slaughterhouse Five." Six years earlier, though, he wrote about the bombing of Hiroshima in "Cat's Cradle," channeling some of the horror he witnessed in Dresden to write about the dropping of the atomic bomb. (Some users may experience a paywall.)

Hear the story of the daring Doolittle Raid, America's first strike back at Japan

This podcast recounts the 1942 Doolittle Raid, when US airmen launched a risky bombing mission over Japan just months after Pearl Harbor. The episode also highlights Jimmy Doolittle's leadership, piloting skills, and his lifelong impact on aviation.

Every day, lightning releases several Hiroshima bombs' worth of energy into the atmosphere

If all this lightning struck one location at once, the bolt would be the diameter of the center circle of a basketball court, turning the entire court into a crater. Its heat would ignite surfaces for miles around, and its shockwave would demolish buildings.

Nuclear weapons in WWII

This 14-minute interactive documentary broaches the subject of the human cost of nuclear warfare. Comparing the number of deaths during World War II with the projected deaths of a nuclear exchange, the video can be paused to delve deeper into individual statistics, historical tidbits, and more data that shows the terrible price humanity would pay.

The attacks prompted a quick jump in American public support for war

In a Gallup poll taken days after the attack, an extraordinary 97% of Americans approved Congress declaring war on Japan—reflecting overwhelming national unity in the wake of the strike.

See a visualization of the Japanese attack on Pearl Harbor.

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While both are nuclear weapons, atomic bombs release nuclear energy by splitting large atomic nuclei, whereas hydrogen bombs derive most of their energy from fusing heavy hydrogen isotopes.

The threat of nuclear annihilation reshaped global diplomacy

The first use of atomic weapons introduced the possibility of a war with no survivors. This article examines how nuclear fear shaped Cold War diplomacy and continues to influence international relations today.

During the Cold War, a mid-air fire led to a nuclear bomber crash in Greenland that left a piece of a hydrogen bomb missing to this day.

The Tsar Bomba was the most powerful nuclear weapon ever tested

In 1961, the Soviet Union detonated AN602—known as the Tsar Bomba—the largest nuclear explosion in history. Newly released Russian footage starkly illustrates the unmatched destructive power of this nuclear weapon.

What happened to Americans who were in Japan during Pearl Harbor?

When Japan bombed Pearl Harbor in December 1941, roughly 10,000 American civilians were stranded in Japanese-occupied territory. Tense diplomatic negotiations eventually secured two prisoner exchanges conducted via ship across 20,000 nautical miles to return nearly 3,000 Allied civilians, while Japanese Americans in North and South America were sent in the opposite direction, many to a country they had never called home.

Japan's attack on Pearl Harbor caused heavy losses but failed to cripple the US navy

Japan’s air assault sank or damaged 18 warships (including eight battleships) and destroyed 188 aircraft, killing 2,403 Americans, yet all three Pacific Fleet aircraft carriers were absent and survived, and vital infrastructure like oil depots and repair yards remained intact—preserving core US naval power and enabling a rapid recovery. Watch original reporting here.

A US project proposed a 10-gigaton nuclear bomb capable of global devastation

Planned in the early 1950s by US scientists, Project Sundial aimed to create a 10-gigaton thermonuclear bomb—hundreds of times more powerful than any weapon ever built. Had it been tested, it was expected to cause global environmental catastrophe.

Hitler declared war on the United States four days after Pearl Harbor

Despite having no treaty obligation to join Japan’s fight, Hitler declared war on the US on Dec. 11, 1941. The move pulled America into the European theater and is widely seen as one of Hitler’s most strategic blunders.

The Chernobyl disaster released more radioactive material than the Hiroshima bomb.

Worried that Nazi Germany could weaponize nuclear fission first, Albert Einstein wrote a 1939 letter warning President Roosevelt about the possibility of atomic bombs—a decision he later regretted.

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

The Pearl Harbor attack led to the mass internment of Japanese Americans

In the months after Pearl Harbor, the US forcibly removed and incarcerated about 120,000 Japanese Americans—two-thirds of them citizens. Driven by fear and racism, the policy is now recognized as a grave violation of civil rights.

The Soviet Union’s surprising first atomic test ended the US nuclear monopoly

In 1949, the USSR successfully tested its first atomic bomb—ending the US monopoly on nuclear weapons and sparking an arms race that would define the Cold War.

The perplexing Battle of Los Angeles in 1942 generated swaths of UFO conspiracies

On Feb. 24-25, 1942, weeks after the Pearl Harbor attack, a US military radar warned of enemy aircraft. A citywide blackout went into effect, powerful searchlights were lit up, and US forces fired artillery at what they believed to be the enemy. However, no confirmed enemy planes were ever identified. Eyewitnesses reported seeing large objects flying overhead, and much of the public speculated about UFOs and extraterrestrial attacks.

The first nuclear reactor was built three years after nuclear fission was discovered

After learning that large atomic nuclei release energy upon being split apart, scientists quickly researched how to control the reaction to make electricity. Fusion—combining small atomic nuclei—generates massive energy in stars and hydrogen bombs.

Simulate the impact of an antimatter bomb, which releases energy from the annihilation of matter with antimatter, around the world.

The attack at Pearl Harbor required nearly a year of planning and preparation

In early 1941, Admiral Isoroku Yamamoto ordered detailed planning for a surprise carrier strike on Pearl Harbor. Japanese teams spent months refining torpedo modifications, training pilots, and rehearsing the complex attack.

The US asked Japan to leave China less than two weeks before Pearl Harbor

On Nov. 26, 1941, Secretary of State Cordell Hull issued a note calling on Japan to withdraw from China and Indochina—terms Tokyo saw as impossible. The note confirmed to Japanese leaders that diplomacy had collapsed, accelerating plans for the Pearl Harbor strike (which had been formally approved Nov. 5).

Visualizing the chemistry of nuclear weapons

Nuclear weapons have devastating effects, but the science of how they work is atomically small. There are two main types of nuclear reaction: fission and fusion. The fission bomb produces immense energy by splitting an atom, the result of firing a...

The discovery of the neutron paved the way for nuclear weapons

In 1932, James Chadwick discovered the subatomic particle when trying to explain the radiation emitted by beryllium after it was bombarded with alpha particles. The radiation’s ability to eject protons from a target suggested a chargeless particle with slightly more mass than a proton.

US intelligence failures contributed to the success of the Japanese attack

Despite breaking Japan’s diplomatic codes, US agencies failed to integrate warnings, successfully track Japan’s carriers, or even believe a Hawaii strike was possible (they also had not cracked Japan’s naval codes). Missed signals, ignored reports and poor coordination led to one of the worst intelligence failures in US history.

J. Robert Oppenheimer’s grandson says his grandfather would back nuclear power

While the "father of the atomic bomb" referred to the bomb as "an evil thing," after the Manhattan Project, he also described nuclear energy’s potential as an environmentally friendly solution to address the world's energy problem.

Roosevelt’s post-Pearl Harbor address became one of America’s most iconic speeches

Delivered to a joint session of Congress on Dec. 8, 1941, President Franklin D. Roosevelt declared Dec. 7 “a date which will live in infamy.” The speech, heard by tens of millions of Americans, helped consolidate national support for entering the war.