ENOLA GAY, LITTLE BOY AND HIROSHIMA
In the afternoon of Aug. 5, 1945, on the island of Tinian in the Pacific Ocean, “Little Boy,” the first combat atomic bomb, was taken to a loading pit and lifted into the bomb bay of a modified B-29 Superfortress.
The flight’s weaponeer and bomb commander, Navy Capt. William S. “Deak” Parsons, was worried about crashing on takeoff from Tinian, a distinct possibility with heavily loaded B-29s. He was particularly concerned that the bomb could detonate in a crash and destroy half the island. The decision was made to allow Parsons to arm the bomb in flight.
Parsons began practicing the task of inserting the propellant (four bags of cordite) into the bomb.
The mission was to be piloted by Col. Paul W. Tibbets Jr., commanding officer of the 509th Composite Group.
Tibbets had his mother’s name, Enola Gay, painted on the side of the plane.
TAKING OFF
In the early morning of Aug. 6, the crew boarded the Enola Gay.
The four-engine plane, followed by two observation planes carrying cameras and scientific instruments, took off into the Pacific night. The Enola Gay was one of seven making the trip to Hiroshima, but it was the only plane carrying a bomb.
LITTLE BOY
Little Boy was a gun bomb. At one end of a gun’s barrel was a Uranium-235 target shaped like a sphere with a conical wedge removed from it. Another cone-shaped bullet of U-235 was at the other end with its point toward the gap in the target. The bullet was fired by the charge of cordite at a set altitude after dropping. The force of the impact would weld the two pieces of uranium together, creating a critical mass, and the explosion would follow instantly.
Some time after takeoff, Parsons loaded the cordite into the bomb and armed the device. Enola Gay rendezvoused with the observation planes over Iwo Jima.
Gun breech
assembly
U-235
bullet
U-235
target
Neutron
initiator
Detonator
Box
tailfins
Gun barrel
Cordite
Barometric
sensing ports
Telemetry
monitoring probes
APPROACHING JAPAN
As the Enola Gay came within sight of the Japanese mainland, Tibbets began the climb to the drop altitude above 30,000 feet.
Seoul
Sea of
Japan
200 MILES
KOREA
JAPAN
Tokyo
Kyoto
Hiroshima
Kobe
Osaka
Kokura
Nagasaki
SHIKOKU
Kagoshima
Yakushima
East
China
Sea
Pacific
Ocean
Okinawa
At 7:15 a.m., the Japanese early-warning radar net detected the approach of planes headed for southern Japan. Radio broadcasting stopped in Hiroshima, and air-raid warnings were sounded. The planes approached the coast at a very high altitude.
Iwo Jima
By 8:00 a.m., the air-raid alert was lifted because the radar operator in Hiroshima saw how few planes there were.
Tinian
Hiroshima finally came into the view of the Enola Gay. The target was the T-shaped Aioi Bridge in the center of the city.
Guam
HIROSHIMA
Hiroshima was a city of considerable military importance. It contained the 2nd Army Headquarters, which commanded the defense of southern Japan. The city was a communications center, a storage point and an assembly area for troops.
The city was located on a broad, flat delta of the Ota River, which has seven channel outlets dividing the city into six islands that project into Hiroshima Bay.
On the morning of the bombing, an estimated 348,000 people were in Hiroshima, including 285,000 civilians, 12,000 conscripted Japanese workers, 3,000 conscripted Korean workers, 48,000 Japanese soldiers, and a small number of prisoners of war.
THE BLAST
At 8:15 a.m., Little Boy dropped. The fall to the burst altitude of 1,968 feet lasted 43 seconds. At that moment, Little Boy was moving faster than the speed of sound.
The bomb exploded with a blinding flash above the center of the city.
The burst temperature was estimated at more than 1 million degrees Celsius. It ignited the surrounding air, forming a fireball about 900 feet in diameter.
Thirty seconds after the explosion, the Enola Gay circled to get a better look at what was happening. The city itself was engulfed in black smoke and, although the bomber was flying at 30,000 feet, the mushroom cloud had already risen above it, eventually reaching almost 56,000 feet.
The bomb, which exploded near its target over the center of the city, leveled two square miles. A firestorm incinerated everything within 6,000 feet of ground zero.
The blast wave shattered windows within 10 miles and was felt as far away as 37 miles. More than two-thirds of Hiroshima’s buildings were demolished. The heat ignited fires as far as two miles from ground zero.
The nuclear fireball and the ensuing blast killed 60,000 to 80,000 people in the time it has taken you to read this paragraph, and mortally wounded or seriously injured an estimated 50,000 more.
THE DEVASTATION
27% killed, 37% injured
Completely destroyed
8,200 ft.
Partially destroyed
86% killed, 10% injured
3,000 ft.
Aioi
Bridge
Ground
zero
Hiroshima Bay
4,000 ft.
THE SURVIVORS
The single greatest factor influencing survival was a distance from the center of the explosion. But few who survived could find care, because 90 percent of all medical personnel were killed or disabled. Only three of the 45 civilian hospitals were usable, and medical supplies quickly ran out.
THE INJURIES
Flash burns, caused by the near-instantaneous radiation of heat and light at the moment of the explosion.
Burns resulting from fires.
Injuries such as fractures, lacerations, contusions and abrasions from flying debris, crumbling buildings and other indirect blast effects.
Injuries caused by exposure to radiation, ranging from nausea, bleeding and hair loss to death. Most of those who had been close to the epicenter died within a week.
JAPAN’S UNDERSTANDING
Military headquarters personnel tried to contact the Army Control Station in Hiroshima but were met with silence. Radio stations went off the air, and the main line telegraph stopped working just north of Hiroshima. Reports of a terrible explosion came from some small railway stops within 10 miles of the city and were transmitted to the headquarters of the Japanese General Staff. The Japanese were puzzled. They knew of no large enemy raid over Hiroshima.
Tokyo’s first knowledge of what had really caused the disaster came from President Harry S. Truman’s announcement in Washington 16 hours after Hiroshima had been devastated.
“Sixteen hours ago an American airplane dropped one bomb on Hiroshima. It is an atomic bomb. We are now prepared to obliterate more rapidly and completely every productive enterprise the Japanese have above ground in any city. If they do not now accept our terms they may expect a rain of ruin from the air the like of which has never been seen on this earth."
— President Harry S. Truman
ENOLA GAY, LITTLE BOY AND HIROSHIMA
In the afternoon of Aug. 5, 1945, on the island of Tinian in the Pacific Ocean, “Little Boy,” the first combat atomic bomb, was taken to a loading pit and lifted into the bomb bay of a modified B-29 Superfortress.
The flight’s weaponeer and bomb commander, Navy Capt. William S. “Deak” Parsons, was worried about the possibility of crashing on takeoff from Tinian, a distinct possibility with heavily loaded B-29s. He was particularly concerned that the bomb could detonate in a crash and destroy half the island. The decision was made to allow Parsons to arm the bomb in flight.
Parsons began practicing the task of inserting the propellant (four bags of cordite) into the bomb.
The mission was to be piloted by Col. Paul W. Tibbets Jr., commanding officer of the 509th Composite Group.
TAKING OFF
In the early morning of Aug. 6, the crew boarded the Enola Gay.
The four-engine plane, followed by two observation planes carrying cameras and scientific instruments, took off into the Pacific night. The Enola Gay was one of seven making the trip to Hiroshima, but it was the only plane carrying a bomb.
LITTLE BOY
Little Boy was a gun bomb. At one end of a gun’s barrel was a Uranium-235 target shaped like a sphere with a conical wedge removed from it. Another cone-shaped bullet of U-235 was at the other end with its point toward the gap in the target. The bullet was fired by the charge of cordite at a set altitude after dropping. The force of the impact would weld the two pieces of uranium together, creating a critical mass, and the explosion would follow instantly.
Some time after takeoff, Parsons loaded the cordite into the bomb and armed the device. Enola Gay rendezvoused with the observation planes over Iwo Jima.
Box tailfins
Gun breech
assembly
Detonator
Cordite
U-235
bullet
Barometric
sensing
ports
Gun
Barrel
U-235
target
Telemetry
monitoring
probes
Neutron
initiator
APPROACHING JAPAN
As the Enola Gay came within sight of the Japanese mainland, Tibbets began the climb to the drop altitude above
30,000 feet.
Sea of
Japan
JAPAN
Tokyo
Hiroshima
SHIKOKU
East
China
Sea
Yakushima
Okinawa
Iwo Jima
Pacific
Ocean
Tinian
Guam
200 MILES
At 7:15 a.m., the Japanese early-warning radar net detected the approach of planes headed for southern Japan. Radio broadcasting stopped in Hiroshima, and air-raid warnings were sounded. The planes approached the coast at a very high altitude.
By 8:00 a.m., the air-raid alert was lifted because the radar operator in Hiroshima saw how few planes there were.
Hiroshima finally came into the view of the Enola Gay. The target was the T-shaped Aioi Bridge in the center of the city.
HIROSHIMA
Hiroshima was a city of considerable military importance. It contained the 2nd Army Headquarters, which commanded the defense of southern Japan. The city was a communications center, a storage point and an assembly area for troops.
The city was located on a broad, flat delta of the Ota River, which has seven channel outlets dividing the city into six islands that project into Hiroshima Bay.
On the morning of the bombing, an estimated 348,000 people were in Hiroshima, including 285,000 civilians, 12,000 conscripted Japanese workers, 3,000 conscripted Korean workers, 48,000 Japanese soldiers, and a small number of prisoners of war.
THE BLAST
At 8:15 a.m., Little Boy dropped. The fall to the burst altitude of 1,968 feet lasted 43 seconds. At that moment, Little Boy was moving faster than the speed of sound.
The bomb exploded with a blinding flash above the center of the city.
The burst temperature was estimated at more than 1 million degrees Celsius. It ignited the surrounding air, forming a fireball about 900 feet in diameter.
Thirty seconds after the explosion, the Enola Gay circled to get a better look at what was happening. The city itself was engulfed in black smoke and, although the bomber was flying at 30,000 feet, the mushroom cloud had already risen above it, eventually reaching almost 56,000 feet.
The bomb, which exploded near its target over the center of the city, leveled two square miles. A firestorm incinerated everything within 6,000 feet of ground zero.
The blast wave shattered windows within 10 miles and was felt as far away as 37 miles. More than two-thirds of Hiroshima’s buildings were demolished. The heat ignited fires as far as two miles from ground zero.
The nuclear fireball and the ensuing blast killed 60,000 to 80,000 people in the time it has taken you to read this paragraph, and mortally wounded or seriously injured an estimated 50,000 more.
THE DEVASTATION
Completely destroyed
Partially destroyed
27% killed, 37% injured
8,200 ft.
86% killed, 10% injured
3,000 ft.
Aioi
Bridge
Ground
zero
Hiroshima Bay
4,000 ft.
THE SURVIVORS
The single greatest factor influencing survival was a distance from the center of the explosion. Few who survived could find care, because 90 percent of all medical personnel were killed or disabled. Only three of the 45 civilian hospitals were usable, and medical supplies quickly ran out.
THE INJURIES
Flash burns, caused by the near-instantaneous radiation of heat and light at the moment of the explosion.
Burns resulting from fires.
Injuries such as fractures, lacerations, contusions and abrasions from flying debris, crumbling buildings and other indirect blast effects.
Injuries caused by exposure to radiation, ranging from nausea, bleeding and hair loss to death. Most of those who had been close to the epicenter died within a week.
JAPAN’S UNDERSTANDING
Military headquarters personnel tried to contact the Army Control Station in Hiroshima but were met with silence. Radio stations went off the air, and the main line telegraph stopped working just north of Hiroshima. Reports of a terrible explosion came from some small railway stops within 10 miles of the city and were transmitted to the headquarters of the Japanese General Staff. The Japanese were puzzled. They knew of no large enemy raid over Hiroshima.
Tokyo’s first knowledge of what had really caused the disaster came from President Harry S. Truman’s announcement in Washington 16 hours after Hiroshima had been devastated.
“Sixteen hours ago an American airplane dropped one bomb on Hiroshima. It is an atomic bomb. We are now prepared to obliterate more rapidly and completely every productive enterprise the Japanese have above ground in any city. If they do not now accept our terms they may expect a rain of ruin from the air the like of which has never been seen on this earth."
— President Harry S. Truman
BOCKSCAR, FAT MAN AND NAGASAKI
On Aug. 7, 1945, the day after a bomb called Little Boy obliterated much of Hiroshima, U.S. officials meeting in Guam decided to bomb until Japan surrendered.
The modified B-29 Superfortress “Bockscar” was named after its usual commander, Capt. Frederick Bock. But Bock wouldn’t fly it this time. The next mission had been assigned to Maj. Charles Sweeney and his crew, who had accompanied the Enola Gay to Hiroshima.
Bockscar would carry the “Fat Man” bomb. In the early hours of Aug. 9, a broken fuel transfer pump was discovered aboard. The bad fuel pump wasn’t a deal-breaker, but it meant Bockscar wouldn’t be able to access more than 600 gallons of fuel stored in its tail.
At 3:49 a.m. Bockscar and five other B-29s left the island of Tinian, south of Japan, aiming for the industrial city of Kokura, home to Japan’s largest munitions plants.
FAT MAN
The second nuclear bomb that would be dropped on Japan was nicknamed Fat Man for British Prime Minister Winston Churchill. Unlike Little Boy, Fat Man’s explosive power came from plutonium, not uranium. Scientists had originally planned to use a bomb that contained the same gun-type detonation method as Little Boy. But testing went poorly, and the plutonium reaction proved hard to control. So Fat Man was pressed into action with an innovative design. An outer ring of explosive charges compressed the plutonium core with enough pressure to produce a nuclear explosion.
Fast
explosive
Slow
explosive
Box
tailfins
Plutonium-239
hemispheres
Seoul
Sea of
Japan
200 MILES
KOREA
JAPAN
Tokyo
Kyoto
Hiroshima
Kobe
Osaka
Kokura
On Bockscar’s first pass over Kokura, clouds and smoke from recent bombings impaired visibility. Sweeney made two more passes but found no window through which his bomber could see the city. He diverted toward a secondary target, about 100 miles away: downtown Nagasaki.
Nagasaki
SHIKOKU
Kagoshima
Yakushima
East
China
Sea
Okinawa
Pacific
Ocean
Iwo Jima
On the return trip, Sweeney knew Bockscar was dangerously low on fuel. He prepared to make an emergency landing at Okinawa, the closest U.S. base, but couldn’t contact the busy airstrip’s tower. The crew fired all available flares to signal their arrival. As its fuel-starved engines began to fail, the plane cut into active runway traffic and bounced to a stop behind a B-24 that was taking off.
Tinian
Guam
NAGASAKI
Nagasaki was spread across 35 square miles, but most of the population was concentrated in less than four square miles in the Urakami Valley basin, one of two main valleys separated by a mountain spur.
The city was home to a natural harbor and several Mitsubishi industrial plants that made ordnance and other military materials. Almost 90 percent of the labor force of 280,000 worked in the Mitsubishi complex.
The people of Nagasaki had begun to hear about Hiroshima, but they had troubles of their own. Residents had seen what a series of smaller bombing raids had done to their mostly wood-and-tile buildings, and thousands chose to evacuate. That left an estimated 240,000 residents in the city on Aug. 9, plus 9,000 Japanese soldiers and 400 prisoners of war.
THE BLAST
At 7:50 a.m., air-raid sirens sounded, but stopped 40 minutes later.
At 10:58, the city center was
shrouded in clouds, obscuring
the view from Bockscar. Then an
opening appeared over the
Urakami Valley
industrial area.
The air raid sirens didn’t sound again until 11:09 a.m., seven minutes after Fat Man exploded over Nagasaki with the force of more than 21,000 tons of TNT.
Nearly every structure within a mile of ground zero was destroyed. But the walls of the valley largely contained the bomb’s force to less than two square miles and shielded outside areas. More than half the city’s homes were not damaged. A 1946 U.S. government report said that without the topographical protection, the area of damage probably would’ve been five times larger.
Only 400 people had been in the city’s air-raid shelter tunnels, which could’ve held a third of the population. Those 400 would survive, uninjured, except for a few who had been near shaft entrances.
THE DEVASTATION
No exact death toll can be known; estimates range as high as 100,000, but many scholars put the number between 40,000 and 70,000, with a similar number injured.
34% killed, 29% injured
Completely destroyed
8,200 ft.
Partially destroyed
88% killed, 6% injured
3,000 ft.
Ground
zero
4,000 ft.
THE SURVIVORS
A medical school and more than 80 percent of the city’s medical facilities were within 3,000 feet of the explosion’s center and were destroyed. Inside one was Tatsuichiro Akizuki, a doctor, who survived and treated other survivors.
“I saw figures running. Then, looking to the southwest, I was stunned. The sky was as dark as pitch, covered with dense clouds of smoke; under that blackness, over the earth, hung a yellow-brown fog. Gradually the veiled ground became visible, and the view beyond rooted me to the spot with horror. All the buildings I could see were on fire. ... Electricity poles were wrapped in flame like so many pieces of kindling. Trees on the nearby hills were smoking, as were the leaves of sweet potatoes in the fields. To say that everything burned is not enough. It seemed as if the earth itself emitted fire and smoke, flames that writhed up and erupted from underground. The sky was dark, the ground was scarlet, and in between hung clouds of yellowish smoke. Three kinds of color — black, yellow and scarlet — loomed ominously over the people, who ran about like so many ants seeking to escape.”
— Tatsuichiro Akizuki,
A Nagasaki doctor who had been less than a mile from the blast and survived
THE END FOR JAPAN
After the bombing of Hiroshima on Aug. 6, Japan remained defiant. But two days later, the Soviet Union declared war on Japan, and a day after that, Fat Man exploded over Nagasaki. Early on Aug. 10, Japan relayed its desire for peace to the United States, and at noon on Aug. 15, Emperor Hirohito announced the surrender to the Japanese people, saying, “We have resolved to pave the way for a grand peace for all the generations to come by enduring the unendurable and suffering what is insufferable.” The formal surrender occurred Sept. 2 aboard the USS Missouri.
BOCKSCAR, FAT MAN AND NAGASAKI
On Aug. 7, 1945, the day after a bomb called Little Boy obliterated much of Hiroshima, U.S. officials meeting in Guam decided to bomb until Japan surrendered.
The modified B-29 Superfortress “Bockscar” was named after its usual commander, Capt. Frederick Bock. But Bock wouldn’t fly it this time. The next mission had been assigned to Maj. Charles Sweeney and his crew, who had accompanied the Enola Gay to Hiroshima.
Bockscar would carry the “Fat Man” bomb. In the early hours of Aug. 9, a broken fuel transfer pump was discovered aboard. The bad fuel pump wasn’t a deal-breaker, but it meant Bockscar wouldn’t be able to access more than 600 gallons of fuel stored in its tail.
At 3:49 a.m. Bockscar and five other B-29s left the island of Tinian, south of Japan, aiming for the industrial city of Kokura, home to Japan’s largest munitions plants.
FAT MAN
The second nuclear bomb that would be dropped on Japan was nicknamed Fat Man for British Prime Minister Winston Churchill. Unlike Little Boy, Fat Man’s explosive power came from plutonium, not uranium. Scientists had originally planned to use a bomb that contained the same gun-type detonation method as Little Boy. But testing went poorly, and the plutonium reaction proved hard to control. So Fat Man was pressed into action with an innovative design. An outer ring of explosive charges compressed the plutonium core with enough pressure to produce a nuclear explosion.
Box
tailfins
Fast
explosive
Slow
explosive
Plutonium-239
hemispheres
On Bockscar’s first pass over Kokura, clouds and smoke from recent bombings impaired visibility. Sweeney made two more passes but found no window through which his bomber could see the city. He diverted toward a secondary target, about 100 miles away: downtown Nagasaki.
Sea of
Japan
JAPAN
Tokyo
Hiroshima
Nagasaki
SHIKOKU
East
China
Sea
Yakushima
Okinawa
Iwo Jima
Pacific
Ocean
Tinian
Guam
200 MILES
On the return trip, Sweeney knew Bockscar was dangerously low on fuel. He prepared to make an emergency landing at Okinawa, the closest U.S. base, but couldn’t contact the busy airstrip’s tower. The crew fired all available flares to signal their arrival. As its fuel-starved engines began to fail, the plane cut into active runway traffic and bounced to a stop behind a B-24 that was taking off.
NAGASAKI
Nagasaki was spread across 35 square miles, but most of the population was concentrated in less than four square miles in the Urakami Valley basin, one of two main valleys separated by a mountain spur.
The city was home to a natural harbor and several Mitsubishi industrial plants that made ordnance and other military materials. Almost 90 percent of the labor force of 280,000 worked in the Mitsubishi complex.
The people of Nagasaki had begun to hear about Hiroshima, but they had troubles of their own. Residents had seen what a series of smaller bombing raids had done to their mostly wood-and-tile buildings, and thousands chose to evacuate. That left an estimated 240,000 residents in the city on Aug. 9, plus 9,000 Japanese soldiers and 400 prisoners of war.
THE BLAST
At 7:50 a.m., air-raid sirens sounded, but stopped 40 minutes later.
At 10:58, the city center was shrouded in clouds, obscuring the view from Bockscar. Then an opening appeared over the Urakami Valley industrial area.
The air raid sirens didn’t sound again until 11:09 a.m., seven minutes after Fat Man exploded over Nagasaki with the force of more than 21,000 tons of TNT.
Nearly every structure within a mile of ground zero was destroyed. But the walls of the valley largely contained the bomb’s force to less than two square miles and shielded outside areas. More than half the city’s homes were not damaged. A 1946 U.S. government report said that without the topographical protection, the area of damage probably would’ve been five times larger.
Only 400 people had been in the city’s air-raid shelter tunnels, which could have held a third of the population. Those 400 would survive, uninjured, except for a few who had been near shaft entrances.
THE DEVASTATION
No exact death toll can be known; estimates range as high as 100,000, but many scholars put the number between 40,000 and 70,000, with a similar number injured.
Completely destroyed
Partially destroyed
34% killed, 29% injured
8,200 ft.
88% killed, 6% injured
3,000 ft.
Ground
zero
4,000 ft.
THE SURVIVORS
A medical school and more than 80 percent of the city’s medical facilities were within 3,000 feet of the explosion’s center and were destroyed. Inside one was Tatsuichiro Akizuki, a doctor, who survived and treated other survivors.
“I saw figures running. Then, looking to the southwest, I was stunned. The sky was as dark as pitch, covered with dense clouds of smoke; under that blackness, over the earth, hung a yellow-brown fog. Gradually the veiled ground became visible, and the view beyond rooted me to the spot with horror. All the buildings I could see were on fire. ... Electricity poles were wrapped in flame like so many pieces of kindling. Trees on the nearby hills were smoking, as were the leaves of sweet potatoes in the fields. To say that everything burned is not enough. It seemed as if the earth itself emitted fire and smoke, flames that writhed up and erupted from underground. The sky was dark, the ground was scarlet, and in between hung clouds of yellowish smoke. Three kinds of color — black, yellow and scarlet — loomed ominously over the people, who ran about like so many ants seeking to escape.”
— Tatsuichiro Akizuki,
A Nagasaki doctor who had been less than a mile from the blast and survived
THE END FOR JAPAN
After the bombing of Hiroshima on Aug. 6, Japan remained defiant. But two days later, the Soviet Union declared war on Japan, and a day after that, Fat Man exploded over Nagasaki. Early on Aug. 10, Japan relayed its desire for peace to the United States, and at noon on Aug. 15, Emperor Hirohito announced the surrender to the Japanese people, saying, “We have resolved to pave the way for a grand peace for all the generations to come by enduring the unendurable and suffering what is insufferable.” The formal surrender occurred Sept. 2 aboard the USS Missouri.
Sources: The Avalon Project of Yale Law School; U.S. Strategic Bombing Survey; Harry S. Truman Library and Museum; Atomic Heritage Foundation; AtomicArchive.com; U.S. Department of Energy; “World History in Documents: A Comparative Reader,” second edition, edited by Peter N. Stearns; nuclearweaponsarchive.org; johnstonsarchive.net; robinsonlibrary.com.