Everything about the bombing of Hiroshima and Nagasaki

Everything about the bombing of Hiroshima and Nagasaki

On August six 1945, an American B-29 bomber dropped the world’s first deployed atomic bomb over the Japanese city of Hiroshima and on nine, 1945 the United States of America’s B-29 detonated the second nuclear weapons over the Japanese cities of Nagasaki, respectively. That’s how the Bombing of Hiroshima and Nagasaki took place.

The two bombing killed between 129,000 and 226,000 people, most of which were civilians, and remained the only use of nuclear weapons in the war. After which on 15th august Japan’s Emperor Hirohito announced its surrender in World War II.


Pacific war, a major threat of World War II that covered a large portion of the Pacific Ocean, East Asia, and Southeast Asia, with significant engagements occurring as far south as northern Australia and as far north as the Aleutian Islands.

In 1945, the Pacific War between the Empire of Japan and the Allies entered its fourth year. Most Japanese military units fought fiercely, ensuring that the Allied victory would come at an enormous cost.

The total U.S casualties in the war were 1.2 million including military personnel killed and wounded and nearly one million of those casualties occurred during the first year of the war. 

Fighting continued in the peripheral theatres of the Pacific War in 1945, with the Allies returned to the Philippines and recaptured  Burma.

Offensives were undertaken to reduce the Japanese forces remaining in Bougainville, New Guinea, and the Philippines. By April 1945, the American forces landed on Okinawa where heavy fighting continued till June.

Along the way, the ratio of Japanese to American casualties dropped from five to one in the Philippines to two to one on Okinawa. Some Japanese soldiers were taken prisoner, most fought until they were killed or committed suicide.

Okinawa saw the first use by the Japanese of a suicide weapon called baka. It was a glider loaded with explosives, powered by rockets, and guided to its target by a single pilot who plunged to death along with his glider. The baka was brought within range of its target by a bombing plane and then released.

For U.S. troops the Okinawa invasion had been the longest and bloodiest Pacific campaign since Guadalcanal in 1942. Total U.S. casualties for the campaign, including naval and air units, ranged upward from 12,000 killed and 36,000 wounded. Thirty-four U.S. ships were sunk and 368 damaged. It was estimated that Japanese losses exceeded 100,000 killed.

As the Allies advanced towards Japan, conditions became steadily worse for the Japanese people. Japan’s merchant fleet declined from 5,250,000 gross tons in 1941 to 557,000 tons in August 1945 Lack of raw materials forced the Japanese war economy into a steep decline after the middle of 1944, hunger and malnutrition became widespread. In February 145, Prince Fumimaro Konoe advised Emperor Hirohito that defeat was inevitable, and urged him to abdicate.

Invading Japan

Operation Downfall was an Allied plan to invade Japan during the end of World War II in 1945. This operation had two parts: Operation Olympic and Operation Coronet.

Further, the operation was called off as on June 15, 1945, a study by the Joint War Plans Committee who provided planning information to the Joint Chiefs of Staff, estimated that Olympic would result in 130,000 to 220,000 U.S. casualties, with U.S. dead in the range from 25,000 to 46,000 after insights gained from the Battle of Okinawa.

Air Strikes

While the United States had plans for air strikes for Japan, the Allied bases were captured in the western Pacific within the first week of conflict, so the offense did not begin till 1944 when Boeing b-29 Superfortress was ready to be used in the war.

The operation involved India based b-29 through bases in China to make a series of raids on specific targets on Japan. This plan failed to achieve its objective due to some logistical problems, mechanical difficulties, the vulnerability of Chinese bases, and extreme range required to reach the Japanese cities.

Brigadier General Haywood S. Hansell suggested that Guan, Tinian, and Saipan in the Mariana Island would be better based for the B-29, but at that time they were acquired by the Japanese, so the islands were captured between June and August 1944.

Strategies were shifted for air combat. But as the China-based air raids, the Mariana bases were also not effective in their high-altitude precision bombing Japan due to some logistical and technical difficulties like unfavorable weather, advanced aircraft, and remote locations.

After Hansell’s early retirement due to loss of hearing disability his successor, Major General Curtis LeMay resumed from January 1945, continued the same technique with the same unsuccessful results.

Under the pressure of the United States Army Air Force (USAAF), LeMay had to change his tactics to low-level incendiary raids to destroy their production capabilities, thus changing from precision bombing to area bombardment with incendiaries. The air offensives’ aim was to kill or disable civilian employees and to destroy war industries.

Over the next 6 months, LeMay firebombed 67 Japanese cities. The firebombing of Tokyo on 9-10 March destroyed 16 square miles of the city killing an estimated 100,000 people; it was the deadliest bombing raid of the war, while b-29 shot down. And by mid-June six largest cities of Japan were completely ruined.

The Japanese military was unable to stop the Allied attacks and the country’s civil defense preparations proved inadequate. Japanese fighters and anti-aircraft guns had difficulty engaging bombers flying at high altitudes.

The Imperial Japanese Army Air Service and the navy stopped intercepting the air raid as they were saving aircraft and fuel for the expected invasion, while the Japanese decided to resume attacks on Allied forces from late June, but there were only a few operational fighters available for this change is plan to obstruct the raids.  

The Beginning of the end 

The Origin- “Manhattan Project”

 Before the outbreak of war in 1939, American scientists, many of them refugees from fascist regimes in Europe, were alarmed by nuclear weapons research being conducted in Nazi Germany. So they took steps to organize a project to exploit the newly recognized fission process for military purposes.

The first contact with the government was made by G.B. Pegram of Columbia University, who arranged a conference between Enrico Fermi and the Navy Department in March 1939.

In the summer of 1939, Albert Einstein was persuaded by his fellow scientists to use his influence and present the military potential of an uncontrolled fission chain reaction to Pres. Franklin D. Roosevelt. 

In 1940, the U.S. government began funding its own atomic weapons development program, which came under the joint responsibility of the Office of Scientific Research and Development and the War Department was created in June 1941.

Over the next several years, the program’s scientists worked on producing the key materials for nuclear fission—uranium-235 and plutonium (Pu-239).

They sent them to Los Alamos, New Mexico, where a team led by J. Robert Oppenheimer worked to turn these materials into a workable atomic bomb Early on the morning of July 16, 1945, the Manhattan Project held its first successful test of an atomic device a plutonium bomb at the Trinity test site at Alamogordo, New Mexico.

The Manhattan Project had produced two types of atomic bombs: “Fat Man”, a plutonium implosion-type nuclear weapon; and “Little Boy”, an enriched uranium gun-type fission weapon.  

No Surrender Japan

By the time of the Trinity test, the Allied powers had already defeated Germany in Europe. Japan, however, vowed to fight to the bitter end in the Pacific, despite clear indications (as early as 1944) that they had little chance of winning.

In fact, between mid-April 1945 (when President Harry Truman took office) and mid-July, Japanese forces inflicted Allied casualties totaling nearly half those suffered in three full years of war in the Pacific, proving that Japan had become even more deadly when faced with defeat.

The target 

In April 1945, a Target Committee was formed to decide the dropping of the bombs. The Target Committee nominated five places

  1. Hiroshima: Industrial center and major military headquarters
  2. Kokura: Largest munitions plant.
  3. Yokohama: Urban center for aircraft manufacture  machine tools, docks, electrical equipment, and oil refineries
  4. Niigata: Port with steel and Aluminum plants and an oil refinery 
  5. Kyoto: A major industrial center

The target committee agreed that psychological factors in the target selection were of great importance.

But on May 30 Stimson asked Groves to remove Kyoto from the target list because of its historical, religious and cultural significance. Further on July 25, Nagasaki replaced Kyoto. It was a major port and one of the largest ship building and repair centers of Japan.

The Agreement

Due to the ‘Quebec Agreement’ signed by the United States and the United Kingdom, which stated no nuclear weapon would be used against another country without mutual consent, a meeting of Combined Policy Committee was held in the Pentagon on 4th July 1945, where  Field Marshal Sir Henry Maitland Wilson announced the British government concurred with the use of nuclear weapons against Japan, which would be officially recorded as a decision of the Combined Policy Committee.

Potsdam Declaration

In late July, Japan’s militarist government rejected the Allied demand for surrender put forth in the Potsdam Declaration, was an ultimatum issued by the United States, Great Britain, and China on July 26, 1945, calling for the unconditional surrender of Japan which threatened the Japanese with “Inevitable and complete destruction” if they refused. On July 28, the Japanese papers reported that the Potsdam Declaration was rejected by the Japanese Government.

Little boy and Fat Man

Hiroshima at the time of war was an Industrial hub with major military headquarters located roughly 500 miles from Tokyo. The most important of which was the headquarters of Field Marshal Shunroku Hata’s Second General Army, which commanded the defense of all of southern Japan.  

The bombing of Hiroshima and Nagasaki (Mushroom cloud)

Hiroshima’s population was around 350,000 and an estimated 40,000 Japanese military personnel were stationed in the city. As Hiroshima was the primary target for the Atomic bomb on 6th August a B-29 Enola gay named after pilot Tibbets’s mom took off from Tinian an approximate six-hour flight time to Japan.

On the night of 5th August Japanese radar detected several American Aircraft headed to the southern part. All clear was sounded in Hiroshima at 0.05 am.

About an hour before the bombing Enola Gay picked up a message reading “Cloud cover less than 3/10th at all altitudes. Advice: bomb primary.” Followed by an all-clear again at Hiroshima at 7:09 am. 

An hour later Tibbets handed his control over to his bombardier, Major Thomas Ferebee. And on 8:15 am Little Boy containing about 65kg of Uranium-235 was released and took 44.4 seconds to fall from the aircraft to detonate at a height of about 1,900 feet (580 m) above the city.  

People below described it as a blinding flashlight followed by a loud booming sound. 70,000-80,000 civilians died with 20,000 Japanese military personnel at the time of the blast and more 70,000 were injured by the blast and resultant firestorm. Everything was burned in a radius of 2 kilometers.

After the bombing of Hiroshima, American president Truman issued a statement stating: “We may be grateful to Providence” and that the Allied forces had “spent two billion dollars on the greatest scientific gamble in history—and won”. Warning Japan that if they don’t stop, might expect a rain of ruin from air followed by sea and land force.

The message soon reached Japan stating that more Japanese cities would face a similar fate in the absence of immediate acceptance of the terms of the Potsdam Declaration and emphatically urged civilians to evacuate major cities. On 9th August the Soviet Union officially declared war on Japan.

No indication of surrender from Japan, they proceeded with dropping another bomb on Nagasaki on the 11th but due to poor flying conditions, it was rescheduled two days prior on 9th August.

Nagasaki which a trade-off of Kyoto was a major port and one of the largest shipbuilding and repair center of Japan the Major companies in the city were Mitsubishi Shipyards, Electrical Shipyards, Arms Plant, and Steel and Arms Works, which employed about 90 percent of the city’s labor force and city’s industries, with its population was estimated to be 263,000 including 9,000 Japanese soldiers.

On 9th August around 2:47 am Bockscar, flown by Sweeney’s crew, lifted off from Tinian island with Fat Man a plutonium implosion-type nuclear weapon with primary target Kokura.

The fuel running low because of the failed fuel pump, Bockscar and TheGreat Artiste headed for their secondary target, Nagasaki. Fuel consumption calculations made en route indicated that Bockscar had insufficient fuel to reach Iwo Jima and would be forced to divert to Okinawa, which had become entirely Allied-occupied territory only six weeks earlier.

At about 07:50 Japanese time, an air raid alert was sounded in Nagasaki, but the “all clear” signal was given at 08:30. When only two B-29 Superfortresses were sighted at 10:53 Japanese Time (GMT+9), the Japanese apparently assumed that the planes were only on reconnaissance and no further alarm was given.

At 11:01 Bockscar’s bombardier Captain Kermit Beahan dropped a core of 55kgs of Plutonium over the city’s industrial valley the bomb detonated 47 seconds later at about 165 feet above the ground. 

Unlike Little boy, Fat man was way powerful but the topography of Nagasaki, which was nestled in narrow valleys between mountains, reduced the bomb’s effect.

Casualties, after the bombing were not much compared to Hiroshima and deaths, vary from 22,000 to 75,000 people with only 150 Japanese deaths recorded; the radius of total destruction was 1.6 kilometers followed by fire across the northern part of the city to 3.2 kilometers to the south of the bomb.


Another atomic was ready to be used on 19th august and more three in September and further in October, but on 15th August 1945, Emperor Hirohito announced his country’s surrender in a radio broadcast.

In his declaration, Hirohito referred to the atomic bombings and did not explicitly mention the Soviets as a factor for surrender. After the surrender of Japan, two days of national holiday were announced for celebrations in the UK, the US, and Australia.

On the same day, the United States president addressed the crowd gathered outside the White House stated:  “This is the day we have been waiting for since Pearl Harbor. This is the day when fascism finally dies, as we always knew it would.”

The following day Emperor Hirohito was heard on the radio for the first time and in which he blamed the ‘new and cruel bomb’ as an unconditional surrender for Japan.

The news spread quickly, and “Victory in Japan” or “V-J Day” celebrations broke out across the Allied nations. The formal surrender agreement was signed on September 2, aboard the U.S. battleship Missouri, anchored in Tokyo Bay.

The Hiroshima and Nagasaki bombing was the only use of nuclear bombs in World War II and hence the war came to an end on 19th September 1945.