Little Boy
Atomic bomb dropped on Hiroshima
Little Boy was a type of atomic bomb created by the United States as part of the Manhattan Project during World War II. The name is also often used to describe the specific bomb (L-11) used in the bombing of the Japanese city of Hiroshima by the Boeing B-29 Superfortress "Enola Gay" on 6 August 1945, making it the first nuclear weapon used in warfare, and the second nuclear explosion in history, after the Trinity nuclear test. It exploded with an energy of approximately and had an explosion radius of approximately which caused widespread death across the city. It was a gun-type fission weapon which used uranium that had been enriched in the isotope uranium-235 to power its explosive reaction.
Little Boy was developed by Lieutenant Commander Francis Birch's group at the Los Alamos Laboratory. It was the successor to a plutonium-fueled gun-type fission design, Thin Man, which was abandoned in 1944 after technical difficulties were discovered. Little Boy used a charge of nitrocellulose to fire a hollow cylinder (the "bullet") of highly enriched uranium through an artillery gun barrel into a solid cylinder (the "target") of the same material. The design was highly inefficient: the weapon used on Hiroshima contained of uranium, but less than a kilogram underwent nuclear fission. Unlike the implosion design developed for the Trinity test and the Fat Man bomb design that was used against Nagasaki, which required sophisticated coordination of shaped explosive charges, the simpler but inefficient gun-type design was considered almost certain to work, and was never tested prior to its use at Hiroshima.
After the war, numerous components for additional Little Boy bombs were built. By 1950, at least five weapons were completed; all were retired by November 1950.
Naming the bomb.
There are two primary accounts of how the first atomic bombs got their names. Los Alamos Laboratory and Project Alberta physicist Robert Serber stated, many decades after the fact, that he had named the first two atomic bomb designs during World War II based on their shapes: Thin Man and Fat Man. The "Thin Man" was a long, thin device, and its name came from the Dashiell Hammett detective novel and series of movies about "The Thin Man". The "Fat Man" was round and fat so it was named after Kasper Gutman, a rotund character in Hammett's 1930 novel "The Maltese Falcon", played by Sydney Greenstreet in the 1941 film version. Little Boy was named by others as an allusion to Thin Man since it was based on its design. It was also sometimes referred to as the "Mark I" nuclear bomb design, with "Mark II" referring to the abandoned Thin Man, and "Mark III" to the "Fat Man."
In September 1945, another Project Alberta physicist, Norman F. Ramsey, stated in his brief "History of Project A," that the early bomb ballistic test shapes designs were referred to as "Thin Man" and "Fat Man" by (unspecified) "Air Force representatives" for "security reasons," so that their communications over telephones sounded "as if they were modifying a plane to carry Roosevelt (the Thin Man) and Churchill (the Fat Man)," as opposed to modifying the B-29s to carry the two atomic bomb shapes as part of Project Silverplate in late 1943.
Another explanation of the names, from a classified United States Air Force history of Project Silverplate from the 1950s, implies a possible reconciliation of the two versions: that the terms "Thin Man" and "Fat Man" were first developed by someone at or from Los Alamos (i.e., Serber), but were consciously adopted by the officers in Silverplate when they were adopting their own codenames for their own project (including "Silverplate"). As Silverplate involved modifying B-29s for a secret purpose, deliberately using codenames that would align with modifying vehicles for Roosevelt and Churchill would serve their needs well.
Development.
Early gun-type design work.
Because of its perceived simplicity, the gun-type nuclear weapon design was the first approach pursued by the scientists working on bomb design during the Manhattan Project. In 1942, it was not yet known which of the two fissile materials pathways being simultaneously pursued—uranium-235 or plutonium-239—would be successful, or if there were significant differences between the two fuels that would impact the design work. Coordination with British scientists in May 1942 convinced the American scientists, led by J. Robert Oppenheimer, that the atomic bomb would not be difficult to design and that the difficulty would lie only in the production of fuel. Calculations in mid-1942 by theoretical physicists working on the project reinforced the idea that an ordinary artillery gun barrel would be able to impart sufficient velocity to the fissile material projectile.
Several different weapon designs, including autocatalytic assembly, a nascent version of implosion, and alternative gun designs (e.g., using high explosives as a propellent, or creating a "double gun" with two projectiles) were pursued in the early years of the project, while the facilities to manufacture fissile material were being constructed. The belief that the gun design would be an easy engineering task once fuel was available led to a sense of optimism at Los Alamos, although Oppenheimer established a small research group to study implosion as a fallback in early 1943. A full ordnance program for gun-design development was established by March 1943, with expertise provided by E.L. Rose, an experienced gun designer and engineer. Work was begun to study the properties of barrels, internal and external ballistics, and tampers of gun weapons. Oppenheimer led aspects of the effort, telling Rose that "at the present time [May 1945] our estimates are so ill founded that I think it better for me to take responsibility for putting them forward." He soon delegated the work to Naval Captain William Sterling Parsons, who, along with Ed McMillan, Charles Critchfield, and Joseph Hirschfelder would be responsible for rendering the theory into practice.
Concern that impurities in reactor-bred plutonium would make predetonation more likely meant that much of the gun-design work was focused on the plutonium gun. To achieve high projectile velocities, the plutonium gun was long with a narrow diameter (suggesting its codename as the Thin Man) which created considerable difficulty in its ballistics dropping from aircraft and fitting it into the bomb bay of a B-29.
In early 1944, Emilio G. Segrè and his P-5 Group at Los Alamos received the first samples of plutonium produced from a nuclear reactor, the X-10 Graphite Reactor at Clinton Engineer Works in Oak Ridge, Tennessee. Analyzing it, they discovered that the presence of the isotope plutonium-240 (Pu-240) raised the rate of spontaneous fission of the plutonium to an unacceptable amount. Previous analyses of plutonium had been made from samples created by cyclotrons and did not have as much of the contaminating isotope. If reactor-bred plutonium was used in a gun-type design, they concluded, it would predetonate, causing the weapon to destroy itself before achieving the conditions for a large-scale explosion.
From Thin Man to Little Boy.
As a consequence of the discovery of the Pu-240 contamination problem, in July 1944 almost all research at Los Alamos was redirected to the implosion-type plutonium weapon, and the laboratory was entirely reorganized around the implosion problem. Work on the gun-type weapon continued under Person's Ordnance (O) Division, for use exclusively with highly enriched uranium as a fuel. All the design, development, and technical work at Los Alamos was consolidated under Lieutenant Commander Francis Birch's group.
In contrast to the plutonium implosion-type nuclear weapon and the plutonium gun-type fission weapon, the uranium gun-type weapon was much simpler to design. As a high-velocity gun was no longer required, the overall length of the gun barrel could be dramatically decreased, and this allowed the weapon to fit into a B-29 bomb bay without difficulty. Though not an optimal use of fissile material compared to the implosion design, it was seen as a nearly guaranteed weapon.
The design specifications were completed in February 1945, and contracts were let to build the components. Three different plants were used so that no one would have a copy of the complete design. The gun and breech were made by the Naval Gun Factory in Washington, D.C.; the target case and some other components by the Naval Ordnance Plant in Center Line, Michigan; and the tail fairing and mounting brackets by the Expert Tool and Die Company in Detroit, Michigan. The bomb, except for the uranium payload, was ready at the beginning of May 1945. Manhattan District Engineer Kenneth Nichols expected on 1 May 1945 to have enriched uranium "for one weapon before August 1 and a second one sometime in December", assuming the second weapon would be a gun type; designing an implosion bomb for enriched uranium was considered, and this would increase the production rate. The enriched uranium projectile was completed on 15 June, and the target was completed on 24 July. The target and bomb pre-assemblies (partly assembled bombs without the fissile components) left Hunters Point Naval Shipyard, California, on 16 July aboard the heavy cruiser , arriving on 26 July. The target inserts followed by air on 30 July.
Although all of its components had been individually tested, no full test of a gun-type nuclear weapon occurred before the Little Boy was dropped over Hiroshima. The only test explosion of a nuclear weapon concept had been of an implosion-type device employing plutonium as its fissile material, which took place on 16 July 1945 at the Trinity nuclear test. There were several reasons for not testing a Little Boy type of device. Primarily, there was the issue of fissile material availability. K-25 at Clinton Engineer Works was designed to produce around 30 kilograms of enriched uranium per month, and the Little Boy design used over 60 kilograms per bomb. So testing the weapon would incur a considerable delay in use of the weapon. (By comparison, B Reactor at the Hanford Site was designed to produce around 20 kilograms of plutonium per month, and each Fat Man bomb used around 6 kilograms of material.) Because of the simplicity of the gun-type design, laboratory testing could establish that its parts worked correctly on their own: for example, dummy projectiles could be shot down the gun barrel to make sure they were "seated" correctly onto a dummy target. Absence of a full-scale test in the implosion-type design made it much more difficult to establish whether the necessary simultaneity of compression had been achieved. While there was at least one prominent scientist (Ernest O. Lawrence) who advocated for a full-scale test, by early 1945 Little Boy was regarded as nearly a sure thing and was expected to have a higher yield than the first-generation implosion bombs.
Though Little Boy incorporated various safety mechanisms, an accidental detonation of a fully-assembled weapon was very possible. Should the bomber carrying the device crash, the hollow "bullet" could be driven into the "target" cylinder, possibly detonating the bomb from gravity alone (though tests suggested this was unlikely), but easily creating a critical mass that would release dangerous amounts of radiation. A crash of the B-29 and subsequent fire could trigger the explosives, causing the weapon to detonate. If immersed in water, the uranium components were subject to a neutron moderator effect, which would not cause an explosion but would release radioactive contamination. For this reason, pilots were advised to crash on land rather than at sea. Ultimately, Parsons opted to keep the explosives out of the Little Boy bomb until after the B-29 had taken off, to avoid the risk of a crash that could destroy or damage the military base from which the weapon was launched.
Design.
The Little Boy was in length, in diameter and weighed approximately . The design used the gun method to explosively force a hollow sub-critical mass of enriched uranium and a solid target cylinder together into a super-critical mass, initiating a nuclear chain reaction. This was accomplished by shooting one piece of the uranium onto the other by means of four cylindrical silk bags of cordite powder. This was a widely used smokeless propellant consisting of a mixture of 65 percent nitrocellulose, 30 percent nitroglycerine, 3 percent petroleum jelly, and 2 percent carbamite that was extruded into tubular granules. This gave it a high surface area and a rapid burning area, and could attain pressures of up to . Cordite for the wartime Little Boy was sourced from Canada; propellant for post-war Little Boys was obtained from the Picatinny Arsenal. The bomb contained of enriched uranium. Most was enriched to 89% but some was only 50% uranium-235, for an average enrichment of 80%. Less than a kilogram of uranium underwent nuclear fission, and of this mass only was transformed into several forms of energy, mostly kinetic energy, but also heat and radiation.
Assembly details.
Inside the weapon, the uranium-235 material was divided into two parts, following the gun principle: the "projectile" and the "target". The projectile was a hollow cylinder with 60% of the total mass (). It consisted of a stack of nine uranium rings, each in diameter with a bore in the center, and a total length of , pressed together into the front end of a thin-walled projectile long. Filling in the remainder of the space behind these rings in the projectile was a tungsten carbide disc with a steel back. At ignition, the projectile slug was pushed along the , smooth-bore gun barrel. The slug "insert" was a 4-inch cylinder, 7 inches in length with a axial hole. The slug comprised 40% of the total fissile mass (). The insert was a stack of six washer-like uranium discs somewhat thicker than the projectile rings that were slid over a 1-inch rod. This rod then extended forward through the tungsten carbide plug, impact-absorbing anvil, and nose plug backstop, eventually protruding out of the front of the bomb casing. This entire target assembly was secured at both ends with locknuts.
When the hollow-front projectile reached the target and slid over the target insert, the assembled super-critical mass of uranium would be completely surrounded by a tamper and neutron reflector of tungsten carbide and steel, both materials having a combined mass of . Neutron initiators inside the assembly were activated by the impact of the projectile into the target.
Counter-intuitive design.
The material was split almost in half, with at one end a group of rings of highly enriched uranium with 40% of the supercritical mass, and at the other end another group of slightly larger rings with 60% of the supercritical mass, which was fired onto the smaller group, with four polonium-beryllium neutron initiators to make the supercritical mass explode.
A hole in the center of the larger piece dispersed the mass and increased the surface area, allowing more fission neutrons to escape, thus preventing a premature chain reaction. But, for this larger, hollow piece to have minimal contact with the tungsten carbide tamper, it must be the projectile, since only the projectile's back end was in contact with the tamper prior to detonation. The rest of the tungsten carbide tamper surrounded the sub-critical mass target cylinder (called the "insert" by the designers) with air space between it and the insert. This arrangement packs the maximum amount of fissile material into a gun-assembly design.
For the first fifty years after 1945, every published description and drawing of the Little Boy mechanism assumed that a small, solid projectile was fired into the center of a larger, stationary target. However, critical mass considerations dictated that in Little Boy the more extensive, hollow piece would be the projectile. Hollow cylinders have higher critical masses than solid pieces of fissile material, because any neutrons encountered by or generated by the material are more likely to get scattered in the air than to continue a chain reaction. The larger piece would also avoid the effects of neutron reflection from the tungsten carbide tamper until it was fully joined with the rest of the fuel. Once joined and with its neutrons reflected, the assembled fissile core would comprise more than two critical masses of uranium-235. In 2004, John Coster-Mullen, a truck driver and model maker from Illinois who had studied every photograph and document on the Hiroshima bomb to make an accurate model, corrected earlier published accounts.
Fuze system.
The fuzing system was designed to trigger at the most destructive altitude, which calculations suggested was . It employed a three-stage interlock system:
Rehearsals.
The Little Boy pre-assemblies were designated L-1, L-2, L-3, L-4, L-5, L-6, L-7, and L-11. Of these, L-1, L-2, L-5, and L-6 were expended in test drops. The first drop test was conducted with L-1 on 23 July 1945. It was dropped over the sea near Tinian in order to test the radar altimeter by the B-29 later known as "Big Stink", piloted by Colonel Paul W. Tibbets, the commander of the 509th Composite Group. Two more drop tests over the sea were made on 24 and 25 July, using the L-2 and L-5 units in order to test all components. Tibbets was the pilot for both missions, but this time the bomber used was the one subsequently known as "Jabit". L-6 was used as a dress rehearsal on 29 July. The B-29 "Next Objective", piloted by Major Charles W. Sweeney, flew to Iwo Jima, where emergency procedures for loading the bomb onto a standby aircraft were practiced. This rehearsal was repeated on 31 July, but this time L-6 was reloaded onto a different B-29, "Enola Gay", piloted by Tibbets, and the bomb was test dropped near Tinian. L-11 was the assembly used for the Hiroshima bomb, and was fully assembled with its nuclear fuel by 31 July.
Bombing of Hiroshima.
Parsons, the "Enola Gay"'s weaponeer, was concerned about the possibility of an accidental detonation if the plane crashed on takeoff, so he decided not to load the four cordite powder bags into the gun breech until the aircraft was in flight. After takeoff, Parsons and his assistant, Second Lieutenant Morris R. Jeppson, made their way into the bomb bay along the narrow catwalk on the port side. Jeppson held a flashlight while Parsons disconnected the primer wires, removed the breech plug, inserted the powder bags, replaced the breech plug, and reconnected the wires. Before climbing to altitude on approach to the target, Jeppson switched the three safety plugs between the electrical connectors of the internal battery and the firing mechanism from green to red. The bomb was then fully armed. Jeppson monitored the bomb's circuits.
The bomb was dropped at approximately 08:15 (JST) on 6 August 1945. After falling for 44.4 seconds, the time and barometric triggers started the firing mechanism. The detonation happened at an altitude of . It was less powerful than the Fat Man, which was dropped on Nagasaki, but the damage and the number of victims at Hiroshima were much higher, as Hiroshima was on flat terrain, while the hypocenter of Nagasaki lay in a small valley. According to figures published in 1945, 66,000 people were killed as a direct result of the Hiroshima blast, and 69,000 were injured to varying degrees. Later estimates put the deaths as high as 140,000 people. The United States Strategic Bombing Survey estimated that out of 24,158 Imperial Japanese Army soldiers in Hiroshima at the time of the bombing, 6,789 were killed or missing as a result of the bombing.
The exact measurement of the explosive yield of the bomb was problematic since the weapon had never been tested. President Harry S. Truman officially announced that the yield was . This was based on Parsons's visual assessment that the blast was greater than what he had seen at the Trinity nuclear test. Since that had been estimated at , speech writers rounded up to 20 kilotons. Further discussion was then suppressed, for fear of lessening the impact of the bomb on the Japanese. Data had been collected by Luis Alvarez, Harold Agnew, and Lawrence H. Johnston on the instrument plane, "The Great Artiste", but this was not used to calculate the yield at the time. More rigorous estimates of the bomb yield and conventional bomb equivalent were made when more data was acquired following the end of the war. A 1985 study estimated the bomb's yield was around .
Physical effects.
After being selected in April 1945, Hiroshima was spared conventional bombing to serve as a pristine target, where the effects of a nuclear bomb on an undamaged city could be observed. While damage could be studied later, the energy yield of the untested Little Boy design could be determined only at the moment of detonation, using instruments dropped by parachute from a plane flying in formation with the one that dropped the bomb. Radio-transmitted data from these instruments indicated a yield of about 15 kilotons.
Comparing this yield to the observed damage produced a rule of thumb called the lethal area rule. Approximately all the people inside the area where the shock wave carried such an overpressure or greater would be killed. At Hiroshima, that area was in diameter.
The damage came from three main effects: blast, fire, and radiation.
Blast.
The blast from a nuclear bomb is the result of X-ray-heated air (the fireball) sending a shock wave or pressure wave in all directions, initially at a velocity greater than the speed of sound, analogous to thunder generated by lightning. Knowledge about urban blast destruction is based largely on studies of Little Boy at Hiroshima. Nagasaki buildings suffered similar damage at similar distances, but the Nagasaki bomb detonated from the city center over hilly terrain that was partially bare of buildings.
In Hiroshima, almost everything within of the point directly under the explosion was completely destroyed, except for about 50 heavily reinforced, earthquake-resistant concrete buildings, only the shells of which remained standing. Most were completely gutted, with their windows, doors, sashes, and frames ripped out. The perimeter of severe blast damage approximately followed the contour at .
Later test explosions of nuclear weapons with houses and other test structures nearby confirmed the 5 psi overpressure threshold. Ordinary urban buildings experiencing it were crushed, toppled, or gutted by the force of air pressure. The picture at right shows the effects of a nuclear bomb-generated 5 psi pressure wave on a test structure in Nevada in 1953.
A major effect of this kind of structural damage was that it created fuel for fires that were started simultaneously throughout the severe destruction region.
Fire.
The first effect of the explosion was blinding light, accompanied by radiant heat from the fireball. The Hiroshima fireball was in diameter, with a surface temperature of , about the same temperature as at the surface of the sun. Near ground zero, everything flammable burst into flame. One famous, anonymous Hiroshima victim, sitting on stone steps from the hypocenter, left a permanent shadow, having absorbed the fireball heat that permanently bleached the surrounding stone. Simultaneous fires were started throughout the blast-damaged area by fireball heat and by overturned stoves and furnaces, electrical shorts, etc. Twenty minutes after the detonation, these fires had merged into a firestorm, pulling in surface air from all directions to feed an inferno which consumed everything flammable.
The Hiroshima firestorm was roughly in diameter, corresponding closely to the severe blast-damage zone. (See the USSBS map, right.) Blast-damaged buildings provided fuel for the fire. Structural lumber and furniture were splintered and scattered about. Debris-choked roads obstructed firefighters. Broken gas pipes fueled the fire, and broken water pipes rendered hydrants useless. At Nagasaki, the fires failed to merge into a single firestorm, and the fire-damaged area was only one-quarter as great as at Hiroshima, due in part to a southwest wind that pushed the fires away from the city.
As the map shows, the Hiroshima firestorm jumped natural firebreaks (river channels), as well as prepared firebreaks. The spread of fire stopped only when it reached the edge of the blast-damaged area, encountering less available fuel. The Manhattan Project report on Hiroshima estimated that 60% of immediate deaths were caused by fire, but with the caveat that "many persons near the center of explosion suffered fatal injuries from more than one of the bomb effects."
Radiation.
Local fallout is dust and ash from a bomb crater, contaminated with radioactive fission products. It falls to earth downwind of the crater and can produce, with radiation alone, a lethal area much larger than that from blast and fire. With an air burst, the fission products rise into the stratosphere, where they dissipate and become part of the global environment. Because Little Boy was an air burst above the ground, there was no bomb crater and no local radioactive fallout.
However, a burst of intense neutron and gamma radiation came directly from the fission of the uranium. Its lethal radius was approximately , covering about half of the firestorm area. An estimated 30% of immediate fatalities were people who received lethal doses of this direct radiation, but died in the firestorm before their radiation injuries would have become apparent. Over 6,000 people survived the blast and fire, but died of radiation injuries. Among injured survivors, 30% had radiation injuries from which they recovered, but with a lifelong increase in cancer risk. To date, no radiation-related evidence of heritable diseases has been observed among the survivors' children.
After the surrender of Japan was finalized, Manhattan Project scientists began to immediately survey the city of Hiroshima to better understand the damage, and to communicate with Japanese physicians about radiation effects in particular. The collaboration became the Atomic Bomb Casualty Commission in 1946, a joint U.S.–Japanese project to track radiation injuries among survivors. In 1975 its work was superseded by the Radiation Effects Research Foundation.
In 1962, scientists at Los Alamos created a mockup of Little Boy known as "Project Ichiban" in order to answer some of the unanswered questions about the exact radiation output of the bomb, which would be useful for setting benchmarks for interpreting the relationship between radiation exposure and later health outcomes. But it failed to clear up all the issues. In 1982, Los Alamos created a replica Little Boy from the original drawings and specifications. This was then tested with enriched uranium but in a safe configuration that would not cause a nuclear explosion. A hydraulic lift was used to move the projectile, and experiments were run to assess neutron emission.
Conventional weapon equivalent.
After hostilities ended, a survey team from the Manhattan Project that included William Penney, Robert Serber, and George T. Reynolds was sent to Hiroshima to evaluate the effects of the blast. From evaluating the effects on objects and structures, Penney concluded that the yield was 12 ± 1 kilotons. Later calculations based on charring pointed to a yield of 13 to 14 kilotons. In 1953, Frederick Reines calculated the yield as . Based on the Project Ichiban data, and the pressure-wave data from "The Great Artiste", the yield was estimated in the 1960s at 16.6 ± 0.3 kilotons. A review conducted by a scientist at Los Alamos in 1985 concluded, on the basis of existing blast, thermal, and radiological data, and then-current models of weapons effects, that the best estimate of the yield was with an uncertainty of 20% (±3 kt). By comparison, the best value for the Nagasaki bomb was evaluated as with an uncertainty of 10% (±2 kt), the difference in uncertainty owing to having better data on the latter.
To put these numerical differences into context, it is necessary to know that the acute effects of nuclear detonations, especially the blast and thermal effects, do not scale linearly, but generally as a cubic root. Specifically, the distance of these effects scale as a function of the yield raised to an exponential power of <templatestyles src="Fraction/styles.css" />1⁄3. So the range of the overpressure damage expected from a detonated 12 kiloton weapon with a height of burst at would be expected to be , whereas a 20 kiloton weapon would have the same range extend to , a difference of only . The areas affected for each would be and , respectively. As such, the practical differences in effects at these yield ranges are smaller than may at first appear, if one assumes that there is a linear relationship between yield and damage.
Although Little Boy exploded with the energy equivalent of around 15 kilotons of TNT, in 1946 the Strategic Bombing Survey estimated that the same blast and fire effect could have been caused by 2.1 kilotons of conventional bombs distributed evenly over the same target area: "220 B-29s carrying 1.2 kilotons of incendiary bombs, 400 tons of high-explosive bombs, and 500 tons of anti-personnel fragmentation bombs." Since the target was spread across a two-dimensional plane, the vertical component of a single spherical nuclear explosion was largely wasted. A cluster bomb pattern of smaller explosions would have been a more energy-efficient match to the target.
Post-WWII.
When the war ended, it was not expected that the inefficient Little Boy design would ever again be required, and many plans and diagrams were destroyed. However, by mid-1946 the Hanford Site reactors were suffering badly from the Wigner effect. Faced with the prospect of no more plutonium for new cores and no more polonium for the initiators for the cores that had already been produced, the Director of the Manhattan Project, Major General Leslie R. Groves, ordered that some Little Boys be prepared as an interim measure until a solution could be found. No Little Boy assemblies were available, and no comprehensive set of diagrams of the Little Boy could be found, although there were drawings of the various components, and stocks of spare parts.
At Sandia Base, three Army officers, Captains Albert Bethel, Richard Meyer, and Bobbie Griffin attempted to re-create the Little Boy. They were supervised by Harlow W. Russ, an expert on Little Boy who served with Project Alberta on Tinian, and was now leader of the Z-11 Group of the Los Alamos Laboratory's Z Division at Sandia. Gradually, they managed to locate the correct drawings and parts, and figured out how they went together. Eventually, they built six Little Boy assemblies. Although the casings, barrels, and components were tested, no enriched uranium was supplied for the bombs. By early 1947, the problem caused by the Wigner effect was on its way to solution, and the three officers were reassigned.
The Navy Bureau of Ordnance began in 1947 to produce 25 "revised" Little Boy mechanical assemblies for use by the nuclear-capable Lockheed P2V Neptune aircraft carrier aircraft (which could be launched from, but not land on, the "Midway"-class aircraft carriers). Components were produced by the Naval Ordnance Plants in Pocatello, Idaho, and Louisville, Kentucky. Enough fissionable material was available by 1948 to build ten projectiles and targets, although there were only enough initiators for six. However, no actual fissionable components were produced by the end of 1948, and only two outer casings were available. By the end of 1950, only five complete Little Boy assemblies had been built. All were retired by November 1950.
The Smithsonian Institution displayed a Little Boy (complete, except for enriched uranium), until 1986. The Department of Energy took the weapon from the museum to remove its inner components, so the bomb could not be stolen and detonated with fissile material. The government returned the emptied casing to the Smithsonian in 1993. Three other disarmed bombs are on display in the United States; another is at the Imperial War Museum in London.
Notes.
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References.
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Enola Gay
US Army Air Forces Boeing B-29 airplane that dropped the first atomic bomb
The Enola Gay () is a Boeing B-29 Superfortress bomber, named after Enola Gay Tibbets, the mother of the pilot, Colonel Paul Tibbets. On 6 August 1945, during the final stages of World War II, it became the first aircraft to drop an atomic bomb in warfare. The bomb, code-named "Little Boy", was targeted at the city of Hiroshima, Japan, and destroyed about three-quarters of the city. "Enola Gay" participated in the second nuclear attack as the weather reconnaissance aircraft for the primary target of Kokura. Clouds and drifting smoke resulted in Nagasaki, a secondary target, being bombed instead.
After the war, the "Enola Gay" returned to the United States, where it was operated from Roswell Army Air Field, New Mexico. In May 1946, it was flown to Kwajalein for the Operation Crossroads nuclear tests in the Pacific, but was not chosen to make the test drop at Bikini Atoll. Later that year, it was transferred to the Smithsonian Institution and spent many years parked at air bases exposed to the weather and souvenir hunters, before its 1961 disassembly and storage at a Smithsonian facility in Suitland, Maryland.
In the 1980s, veterans groups engaged in a call for the Smithsonian to put the aircraft on display, leading to an acrimonious debate about exhibiting the aircraft without a proper historical context. The cockpit and nose section of the aircraft were exhibited at the National Air and Space Museum (NASM) on the National Mall, for the bombing's 50th anniversary in 1995, amid controversy. Since 2003, the entire restored B-29 has been on display at NASM's Steven F. Udvar-Hazy Center. The last survivor of its crew, Theodore Van Kirk, died on 28 July 2014 at the age of 93.
World War II.
Early history.
The "Enola Gay" (Model number B-29-45-MO, Serial number 44-86292, Victor number 82) was built by the Glenn L. Martin Company (later part of Lockheed Martin) at its bomber plant in Bellevue, Nebraska, located at Offutt Field, now Offutt Air Force Base. The bomber was one of the first fifteen B-29s built to the "Silverplate" specification— of 65 eventually completed during and after World War II—giving them the primary ability to function as nuclear "weapon delivery" aircraft. These modifications included an extensively modified bomb bay with pneumatic doors and British bomb attachment and release systems, reversible pitch propellers that gave more braking power on landing, improved engines with fuel injection and better cooling, and the removal of protective armor and gun turrets.
"Enola Gay" was personally selected by Colonel Paul W. Tibbets Jr., the commander of the 509th Composite Group, on 9 May 1945, while still on the assembly line. The aircraft was accepted by the United States Army Air Forces (USAAF) on 18 May 1945 and assigned to the 393d Bombardment Squadron, Heavy, 509th Composite Group. Crew B-9, commanded by Captain Robert A. Lewis, took delivery of the bomber and flew it from Omaha to the 509th base at Wendover Army Air Field, Utah, on 14 June 1945.
Thirteen days later, the aircraft left Wendover for Guam, where it received a bomb-bay modification, and flew to North Field, Tinian, on 6 July. It was initially given the Victor (squadron-assigned identification) number 12, but on 1 August, was given the circle R tail markings of the 6th Bombardment Group as a security measure and had its Victor number changed to 82 to avoid misidentification with actual 6th Bombardment Group aircraft. During July, the bomber made eight practice or training flights and flew two missions, on 24 and 26 July, to drop pumpkin bombs on industrial targets at Kobe and Nagoya. "Enola Gay" was used on 31 July on a rehearsal flight for the actual mission.
The partially assembled Little Boy gun-type fission weapon L-11, weighing , was contained inside a wooden crate that was secured to the deck of the . Unlike the six uranium-235 target discs, which were later flown to Tinian on three separate aircraft arriving 28 and 29 July, the assembled projectile with the nine uranium-235 rings installed was shipped in a single lead-lined steel container weighing that was locked to brackets welded to the deck of Captain Charles B. McVay III's quarters. Both the L-11 and projectile were dropped off at Tinian on 26 July 1945.
Hiroshima mission.
On 5 August 1945, during preparation for the first atomic mission, Tibbets assumed command of the aircraft and named it after his mother, Enola Gay Tibbets, who, in turn, had been named for the heroine of a novel. When it came to selecting a name for the plane, Tibbets later recalled that: <templatestyles src="Template:Blockquote/styles.css" />... my thoughts turned at this point to my courageous red-haired mother, whose quiet confidence had been a source of strength to me since boyhood, and particularly during the soul-searching period when I decided to give up a medical career to become a military pilot. At a time when Dad had thought I had lost my marbles, she had taken my side and said, "I know you will be all right, son."
In the early morning hours, just prior to the 6 August mission, Tibbets had a young Army Air Forces maintenance man, Private Nelson Miller, paint the name just under the pilot's window. Regularly assigned aircraft commander Robert A. Lewis was unhappy to be displaced by Tibbets for this important mission and became furious when he arrived at the aircraft on the morning of 6 August to see it painted with the now-famous nose art.
Hiroshima was the primary target of the first nuclear bombing mission on 6 August, with Kokura and Nagasaki as alternative targets. "Enola Gay", piloted by Tibbets, took off from North Field, in the Northern Mariana Islands, about six hours' flight time from Japan, accompanied by two other B-29s, "The Great Artiste", carrying instrumentation, and a then-nameless aircraft later called "Necessary Evil", commanded by Captain George Marquardt, to take photographs. The director of the Manhattan Project, Major General Leslie R. Groves Jr., wanted the event recorded for posterity, so the takeoff was illuminated by floodlights. When he wanted to taxi, Tibbets leaned out the window to direct the bystanders out of the way. On request, he gave a friendly wave for the cameras.
After leaving Tinian, the three aircraft made their way separately to Iwo Jima, where they rendezvoused at and set course for Japan. The aircraft arrived over the target in clear visibility at . Navy Captain William S. "Deak" Parsons of Project Alberta, who was in command of the mission, armed the bomb during the flight to minimize the risks during takeoff. His assistant, Second Lieutenant Morris R. Jeppson, removed the safety devices 30 minutes before reaching the target area.
The release at 08:15 (Hiroshima time) went as planned, and the Little Boy took 53 seconds to fall from the aircraft flying at to the predetermined detonation height about above the city. "Enola Gay" traveled before it felt the shock waves from the blast. Although buffeted by the shock, neither "Enola Gay" nor "The Great Artiste" was damaged.
The detonation created a blast equivalent to . The U-235 weapon was considered very inefficient, with only 1.7% of its fissile material reacting. The radius of total destruction was about , with resulting fires across . Americans estimated that of the city were destroyed. Japanese officials determined that 69% of Hiroshima's buildings were destroyed and another 6–7% damaged. Some 70,000–80,000 people, 30% of the city's population, were killed by the blast and resultant firestorm, and another 70,000 injured. Out of those killed, 20,000 were soldiers and 20,000 were Korean slave laborers.
"Enola Gay" returned safely to its base on Tinian to great fanfare, touching down at 2:58 pm, after 12 hours 13 minutes. "The Great Artiste" and "Necessary Evil" followed at short intervals. Several hundred people, including journalists and photographers, had gathered to watch the planes return. Tibbets was the first to disembark and was presented with the Distinguished Service Cross on the spot.
Nagasaki mission.
The Hiroshima mission was followed by another atomic strike. Originally scheduled for 11 August, it was brought forward by two days to 9 August owing to a forecast of bad weather. This time, a nuclear bomb code-named "Fat Man" was carried by B-29 "Bockscar", piloted by Major Charles W. Sweeney. "Enola Gay", flown by Captain George Marquardt's Crew B-10, was the weather reconnaissance aircraft for Kokura, the primary target. "Enola Gay" reported clear skies over Kokura, but by the time "Bockscar" arrived, the city was obscured by smoke from fires from the conventional bombing of Yahata by 224 B-29s the day before. After three unsuccessful passes, "Bockscar" diverted to its secondary target, Nagasaki, where it dropped its bomb. In contrast to the Hiroshima mission, the Nagasaki mission has been described as tactically botched, although the mission did meet its objectives. The crew encountered a number of problems in execution and had very little fuel by the time they landed at the emergency backup landing site Yontan Airfield on Okinawa.
Crews.
Hiroshima mission.
"Enola Gay"'s crew on 6 August 1945 consisted of 12 men. The crew was:
Asterisks denote regular crewmen of the "Enola Gay".
Of mission commander Parsons, it was said: "There is no one more responsible for getting this bomb out of the laboratory and into some form useful for combat operations than Captain Parsons, by his plain genius in the ordnance business."
Nagasaki mission.
For the Nagasaki mission, "Enola Gay" was flown by Crew B-10, normally assigned to "Up An' Atom":
Source: Campbell, 2005, pp. 134, 191–192.
Subsequent history.
On 6 November 1945, Lewis flew the "Enola Gay" back to the United States, arriving at the 509th's new base at Roswell Army Air Field, New Mexico, on 8 November. On 29 April 1946, "Enola Gay" left Roswell as part of the Operation Crossroads nuclear weapons tests in the Pacific. It flew to Kwajalein Atoll on 1 May. It was not chosen to make the test drop at Bikini Atoll and left Kwajalein on 1 July, the date of the test, reaching Fairfield-Suisun Army Air Field, California, the next day.
The decision was made to preserve the "Enola Gay", and on 24 July 1946, the aircraft was flown to Davis–Monthan Air Force Base, Tucson, Arizona, in preparation for storage. On 30 August 1946, the title to the aircraft was transferred to the Smithsonian Institution and the "Enola Gay" was removed from the USAAF inventory. From 1946 to 1961, the "Enola Gay" was put into temporary storage at a number of locations. It was at Davis-Monthan from 1 September 1946 until 3 July 1949, when it was flown to Orchard Place Air Field, Park Ridge, Illinois, by Tibbets for acceptance by the Smithsonian. It was moved to Pyote Air Force Base, Texas, on 12 January 1952, and then to Andrews Air Force Base, Maryland, on 2 December 1953, because the Smithsonian had no storage space for the aircraft.
It was hoped that the Air Force would guard the plane, but, lacking hangar space, it was left outdoors on a remote part of the air base, exposed to the elements. Souvenir hunters broke in and removed parts. Insects and birds then gained access to the aircraft. Paul E. Garber of the Smithsonian Institution became concerned about the "Enola Gay"'s condition, and on 10 August 1960, Smithsonian staff began dismantling the aircraft. The components were transported to the Smithsonian storage facility at Suitland, Maryland, on 21 July 1961.
The "Enola Gay" remained at Suitland for many years. By the early 1980s, two veterans of the 509th, Don Rehl and his former navigator in the 509th, Frank B. Stewart, began lobbying for the aircraft to be restored and put on display. They enlisted Tibbets and Senator Barry Goldwater in their campaign. In 1983, Walter J. Boyne, a former B-52 pilot with the Strategic Air Command, became director of the National Air and Space Museum, and he made the "Enola Gay"'s restoration a priority. Looking at the aircraft, Tibbets recalled, was a "sad meeting. [My] fond memories, and I don't mean the dropping of the bomb, were the numerous occasions I flew the airplane ... I pushed it very, very hard and it never failed me ... It was probably the most beautiful piece of machinery that any pilot ever flew."
Restoration.
Restoration of the bomber began on 5 December 1984, at the Paul E. Garber Preservation, Restoration, and Storage Facility in Suitland-Silver Hill, Maryland. The propellers that were used on the bombing mission were later shipped to Texas A&M University. One of these propellers was trimmed to for use in the university's Oran W. Nicks Low Speed Wind Tunnel. The lightweight aluminum variable-pitch propeller is powered by a 1,250 kVA electric motor, providing a wind speed up to . Two engines were rebuilt at Garber and two at San Diego Air & Space Museum. Some parts and instruments had been removed and could not be located. Replacements were found or fabricated, and marked so that future curators could distinguish them from the original components.
Exhibition controversy.
The "Enola Gay" became the center of a controversy at the Smithsonian Institution when the museum planned to put its fuselage on public display in 1995 as part of an exhibit commemorating the 50th anniversary of the atomic bombing of Hiroshima. The exhibit, "The Crossroads: The End of World War II, the Atomic Bomb and the Cold War," was drafted by the Smithsonian's National Air and Space Museum staff, and arranged around the restored "Enola Gay".
Critics of the planned exhibit, especially those of the American Legion and the Air Force Association, charged that the exhibit focused too much attention on the Japanese casualties inflicted by the nuclear bomb, rather than on the motives for the bombing or the discussion of the bomb's role in ending the conflict with Japan. The exhibit brought to national attention many long-standing academic and political issues related to retrospective views of the bombings. After attempts to revise the exhibit to meet the satisfaction of competing interest groups, the exhibit was canceled on 30 January 1995. Martin O. Harwit, Director of the National Air and Space Museum, was compelled to resign over the controversy. He later reflected that
<templatestyles src="Template:Blockquote/styles.css" />The dispute was not simply about the atomic bomb. Rather, the dispute was sometimes a symbolic issue in a "culture war" in which many Americans lumped together the seeming decline of American power, the difficulties of the domestic economy, the threats in world trade and especially Japan's successes, the loss of domestic jobs, and even changes in American gender roles and shifts in the American family. To a number of Americans, the very people responsible for the script were the people who were changing America. The bomb, representing the end of World War II and suggesting the height of American power was to be celebrated. It was, in this judgment, a crucial symbol of America's "good war", one fought justly for noble purposes at a time when America was united. Those who in any way questioned the bomb's use were, in this emotional framework, the enemies of America.
The forward fuselage went on display on 28 June 1995. On 2 July 1995, three people were arrested for throwing ash and human blood on the aircraft's fuselage, following an earlier incident in which a protester had thrown red paint over the gallery's carpeting. The exhibition closed on 18 May 1998 and the fuselage was returned to the Garber Facility for final restoration.
Complete restoration and display.
Its restoration work began in 1984, and eventually required 300,000 staff hours. While the fuselage was on display, from 1995 to 1998, work continued on the remaining unrestored components. The aircraft was shipped in pieces to the National Air and Space Museum's Steven F. Udvar-Hazy Center in Chantilly, Virginia from March–June 2003, with the fuselage and wings reunited for the first time since 1960 on 10 April 2003 and assembly completed on 8 August 2003. The aircraft has been on display at the Udvar-Hazy Center since the museum annex opened on 15 December 2003. As a result of the earlier controversy, the signage around the aircraft provided only the same succinct technical data as is provided for other aircraft in the museum, without discussion of the controversial issues. It read:<templatestyles src="Template:Blockquote/styles.css" />
Boeing's B-29 Superfortress was the most sophisticated propeller-driven bomber of World War II, and the first bomber to house its crew in pressurized compartments. Although designed to fight in the European theater, the B-29 found its niche on the other side of the globe. In the Pacific, B-29s delivered a variety of aerial weapons: conventional bombs, incendiary bombs, mines, and two nuclear weapons.
On 6 August 1945, this Martin-built B-29-45-MO dropped the first atomic weapon used in combat on Hiroshima, Japan. Three days later, Bockscar (on display at the U.S. Air Force Museum near Dayton, Ohio) dropped a second atomic bomb on Nagasaki, Japan. "Enola Gay" flew as the advance weather reconnaissance aircraft that day. A third B-29, "The Great Artiste", flew as an observation aircraft on both missions.
<templatestyles src="Template:Blockquote/styles.css" />"Transferred from the U.S. Air Force"
Wingspan:
Length:
Height:
Weight, empty:
Weight, gross:
Top speed:
Engines: 4 Wright R-3350-57 Cyclone turbo-supercharged radials, 2,200 hp
Crew: 12 (Hiroshima mission)
Armament: two .50 caliber machine guns
Ordnance: Little Boy atomic bomb
Manufacturer: Martin Co., Omaha, Nebraska, 1945
A19500100000
The display of the "Enola Gay" without reference to the historical context of World War II, the Cold War, or the development and deployment of nuclear weapons aroused controversy. A petition from a group calling themselves the Committee for a National Discussion of Nuclear History and Current Policy bemoaned the display of "Enola Gay" as a technological achievement, which it described as an "extraordinary callousness toward the victims, indifference to the deep divisions among American citizens about the propriety of these actions, and disregard for the feelings of most of the world's peoples". It attracted signatures from notable figures including historian Gar Alperovitz, social critic Noam Chomsky, whistle blower Daniel Ellsberg, physicist Joseph Rotblat, writer Kurt Vonnegut, producer Norman Lear, actor Martin Sheen and filmmaker Oliver Stone.
References.
Notes.
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Citations.
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Bibliography.
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Further reading.
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Enola Gay (disambiguation)
The Enola Gay is a USAAF B-29 Superfortress, that dropped Little Boy, the first atomic bomb used in warfare, on Hiroshima in Japan during WWII
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Enola Gay may also refer to:
See also.
Topics referred to by the same term
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 This page lists associated with the title .

Aerial bombing of cities
Bombardment of a city from aircraft
The aerial bombing of cities is an optional element of strategic bombing, which became widespread in warfare during World War I. The bombing of cities grew to a vast scale in World War II and is still practiced today. The development of aerial bombardment marked an increased capacity of armed forces to deliver ordnance from the air against combatants, military bases, and factories, with a greatly reduced risk to its ground forces. The killing of civilians and non-combatants in bombed cities has variously been a deliberate goal of strategic bombing, or unavoidable collateral damage resulting from intent and technology. A number of multilateral efforts have been made to restrict the use of aerial bombardment so as to protect non-combatants and other civilians.
Before World War I.
Kites.
Incendiary kites were first used in warfare by the Chinese. During the Song dynasty the "Fire Crow", a kite carrying incendiary powder, a fuse, and a burning stick of incense was developed as a weapon. Walter de Milemete's 1326 "De nobilitatibus, sapientiis, et prudentiis regum" treatise depicts a group of knights flying kites laden with a black-powder filled firebomb over the wall of city. In the 17th century, the forces of Thai king Phetracha tied gunpowder barrels to kites used for airborne assault.
First Italian War of Independence.
In 1849, Austrian forces besieging Venice during the First Italian War of Independence launched some 200 incendiary balloons, each carrying a 24- to 30-pound bomb that was to be dropped from the balloon with a time fuse over the besieged city. The balloons were launched from land and from the Austrian navy ship SMS "Vulcano" that acted as a balloon carrier, though the attack ended in failure as winds blew the balloons away, none reaching their intended target.
Italian Invasion of Libya.
The first ever air raid was conducted during the Italo-Turkish War by Italian forces against the Ottoman province of Libya on November 1, 1911. Giulio Gavotti dropped 1.5 kg of bombs on Ain Zara, a village 8 km west of the capital Tripoli.
Balkan War.
Adrianople (presently Edirne) was bombed by Bulgaria in 1912 in the First Balkan War. Historically, it was the first bombardment of a city from a heavier-than-air aircraft.
In the morning of 29 October 1912 at 9:30 a.m. the plane Albatros F-3 took off from an airfield near the village of Mustafa Pasha – present day Svilengrad, Bulgaria. The pilot was captain Radul Mikov with spotter and bombardier Prodan Tarakchiev. The airfield was specially created to carry out the take off and landing. According to the report weather conditions were perfect. The flight lasted for 1 hour and 20 minutes and the altitude was 500m. During the flight the crew flew over the city of Edirne, discovered hidden Ottoman forces in the nearby villages and flew towards to city railroad station, near the village of Karaagach. The plane was equipped with two bombs, which were released at 10:00 am over the station. The crew landed successfully at the airfield with 4 holes on the hull.
A number of journalists and military attachés attended the site.
Mexican Revolution.
In May 1914, during the revolution of 1910–17, General Venustiano Carranza, later president, ordered a biplane to bomb Neveria Hill adjacent to the downtown area of Mazatlán in order to take the city. The bomb landed not on target but in a city street and in the process killed four civilians, including a French diplomat, and wounded several others.
World War I.
The first civilian target to be bombed from the air was the Belgian city of Antwerp. This city, at that moment the National Redoubt of Belgium, was bombed during the night of 24–25 August 1914. Instead of targeting the surrounding fortresses, the Zeppelin LZ 25's intention was to bomb the clearly distinguishable historical centre of the city. The zeppelin dropped approximately ten bombs, killing ten people and injuring forty.
The British Royal Naval Air Service (RNAS) undertook the first Entente strategic bombing missions on 22 September 1914 and 8 October, when it bombed the Zeppelin bases in Cologne and Düsseldorf. The aeroplanes carried twenty-pound bombs, and at least one airship was destroyed. On 19 January 1915 two German Zeppelins dropped 24 fifty-kilogram (110 lb) high-explosive bombs and ineffective three-kilogram incendiaries on the English towns of Great Yarmouth, Sheringham, King's Lynn, and the surrounding villages; in all, four people were killed, 16 injured, and monetary damage was estimated at £7,740.
London was bombed for the first time on 30 May 1915. In July 1916, the German government allowed directed raids against urban centers, sparking 23 airship raids in 1916 in which 125 tons of ordnance were dropped, killing 293 people and injuring 691. Gradually British air defenses improved and the Germans also introduced large bomber aircraft for bombing Britain. In 1917 and 1918 there were only eleven Zeppelin raids against England, and the final raid occurred on 5 August 1918, which resulted in the death of KK Peter Strasser, commander of the German Naval Airship Department. By the end of the war, 51 raids had been undertaken, in which 5,806 bombs were dropped, killing 557 people and injuring 1,358. In the course of the Zeppelin raids the Germans lost more than half their airships and 40% of their crew. It has been argued that the raids were effective far beyond material damage inflicted, in diverting and hampering wartime production, and diverting twelve squadrons and over 10,000 men to air defenses.
The British developed an Independent Force of long-range bombers that could bomb Berlin, but the war ended before these raids began.
After the war, bombers' increasing sophistication led to the general belief that aerial bombing would both destroy cities and be impossible to stop; as Stanley Baldwin stated in a 1932 speech, "The bomber will always get through".
Interwar period.
Iraqi revolt against the British.
After World War I, there were protests in Iraq against continued British rule. Many Iraqis across a wide spectrum of opinion opposed the British Mandate for Iraq. The Iraqi revolt against the British began, with peaceful demonstrations in May 1920. Initial demands were rejected by the British administration, and fighting broke out in June 1920. This was suppressed, with many deaths, and at very high costs to the Empire. A policy of 'aerial policing', an invention of Winston Churchill's was brought in. This amounted to aerial bombing of rebelling tribesmen, followed up by pacification by ground troops. This continued up to the mid 1920s. The aerial campaign included Sir Arthur Harris, who commanded a Vickers Vernon squadron engaged in the bombing and strafing of revolting tribesmen. Harris once remarked that "the only thing the Arab understands is the heavy hand."
Somaliland Campaign.
Following the end of World War I, the British stepped up their efforts in their war against the Dervish movement, their sultan Diiriye Guure and emir, the so-called "Mad Mullah", whom they had been fighting for the control the area formerly known as British Somaliland. However, they had been unable to defeat the Dervish movement for nearly 25 years. In January 1920, the British launched a combined aerial and land attack against the Dhulbahante garesas, bombarding Taleeh, the capital of the revolt. The Somaliland Campaign has been described as one of the bloodiest and longest-running conflicts in the history of sub-Saharan Africa and the Somali forces are noted for concurrently repelling the invading British, Italian and Abyssinian forces for a period of 25 years.
Tulsa race massacre.
In the United States during the Tulsa race massacre of May 31 – June 1, 1921, private aircraft flown by white men dropped kerosene bombs on the Greenwood neighborhood.
Cristero War.
During the Cristero War in Mexico in 1929, Irish pilot and mercenary Patrick Murphy mistakenly dropped several improvised "suitcase bombs" on the border town of Naco, Arizona, while bombing government forces in the adjacent town of Naco, Sonora, for the Cristero revolutionaries. The bombing, which caused damage to many buildings and injured several bystanders on the American side of the international border, became the first aerial bombardment of the Continental United States by a foreign power in American history.
Second Italo-Abyssinian War.
The Italians used aircraft against the Ethiopian cities in the Second Italo-Abyssinian War. For example, in February 1936, the Italian invasion forces in the south prepared for a major thrust towards the city of Harar. On 22 March, the "Regia Aeronautica" bombed Harar and Jijiga as a prelude. Both cities were reduced to ruins even though Harar had been declared an "open city".
Spanish Civil War.
During the Spanish Civil War, the Nationalists under Francisco Franco made extensive use of aerial bombing on civilian targets. Nazi Germany gave aircraft to Franco to support the overthrow of the Spanish Republican government. The first major example of this came in November 1936, when German and Spanish aircraft bombed Republican-held Madrid; this bombardment was sustained throughout the Siege of Madrid. Barcelona and Valencia were also targeted in this way. On 26 April 1937, the German "Luftwaffe" (Condor Legion) bombed the Spanish city of Guernica carrying out the most high-profile aerial attack of the war. This act caused worldwide revulsion and was the subject of a famous painting by Picasso, but by the standards of bombings during World War II, casualties were fairly minor (estimates ranging from 500 to 1,500).
Shortly after, the front-page headlines of the "Diario de Almeria", dated June 3, 1937, referred to the press in London and Paris carrying the news of the "criminal bombardment of Almeria by German planes".
Barcelona was bombarded for three days beginning on 16 March 1938, at the height of the Spanish Civil War. Under the command of the Italian dictator Benito Mussolini, Italian aircraft stationed on the island of Majorca attacked 13 times dropping 44 tons of bombs, aimed at the civil population. The medieval Cathedral of Barcelona suffered bomb damage and more than one thousand people died, including many children. The number of people injured is estimated to be in the thousands. Many others Spanish towns and cities were bombed by the German "Legion Condor" and the Italian "Aviazione Legionaria" among them Jaen, Durango, Granollers and Alicante.
The Spanish Republican government also used aerial bombings, but not as extensively, as they did not have as many planes available. Cities such as Valladolid, Granada, Sevilla, Zaragoza or Burgos were bombarded, killing some people. The biggest aerial attack against civil population was in Cabra, a small town away from the war front, and with no strategic value, that was bombed due to an error. 109 people were killed and more than 200 wounded. Planes coming from Barcelona launched three bombs against the Cathedral-Basilica of Our Lady of the Pillar on August 3, 1936. The bombs failed to detonate, but did damage one of the cupolas painted by Goya. The fact was considered a miracle, as, if the bombs had exploded, the eastern half of the Cathedral would have been completely destroyed.
Second Sino-Japanese War.
During the Manchurian Incident of 1931, the Japanese widely used airplanes to indiscriminately bomb key targets and cities, such as Mukden. After the Marco Polo Bridge Incident, the Imperial Japanese Army Air Service, in conjunction with the Imperial Japanese Navy Air Service, began relentlessly bombing Shanghai, Beijing (Peking), Tianjin (Tientsin) and several cities on the Chinese coast from the beginning of the Second Sino-Japanese War in 1937.
The bombing campaigns on Nanjing and Canton which started in September 1937 evoked protests from the Western powers culminating in a resolution by the Far Eastern Advisory Committee of the League of Nations. An example of the many expressions of indignation came from Lord Cranborne, the British Under-Secretary of State For Foreign Affairs: Words cannot express the feelings of profound horror with which the news of these raids had been received by the whole civilized world. They are often directed against places far from the actual area of hostilities. The military objective, where it exists, seems to take a completely second place. The main object seems to be to inspire terror by the indiscriminate slaughter of civilians ...
World War II.
European Theater.
At the beginning of World War II, bombing of cities prior to invasion was an integral part of Nazi Germany's strategy. In the first stages of war, the Germans carried out many bombings of towns and cities in Poland (1939), including the capital Warsaw (also bombed in 1944), with Wieluń being the first city destroyed by 75%. The Soviet Union also attempted strategic bombing against Poland and Finland, bombing Helsinki.
Rotterdam was bombed by Germany at 14 May 1940. The city had already surrendered an hour earlier and the attack was called off, but this did not reach the already flying bombers.
Germany began aerial bombing of British cities immediately after the British declaration of war on Germany in September 1939, while the first British bombing raids against Germany were on the night of 15/16 May 1940, with 78 bombers against oil targets, 9 against steelworks and 9 against marshalling yards, all military and industrial targets in the German hinterland. Oil remained the main British objective until the summer of 1941, although German cities and towns were regularly bombed from May 1940. Previous raids had been carried out by the RAF, but when targets were not found, the bombers returned without making an attack.
After the Fall of France, the Luftwaffe redirected its full attention to the United Kingdom. The scale of the attack increased greatly in July 1940, with 258 civilians killed, and again in August with 1,075 dead. During the night of 25 August, British bombers raided targets in and around Greater Berlin for the first time, in response to the misdirected bombing of Oxford Street and the West End by the Luftwaffe while it was bombing the London docks. On 4 September 1940 Hitler, frustrated by the RAF's superiority over the Luftwaffe and enraged by its bombing of German cities, decided to retaliate by bombing London and other cities in the UK. On 7 September the Luftwaffe began massed attacks on London. The bombing campaign was known in the UK as "the Blitz", and ran from September 1940 through to May 1941. The Coventry Blitz and the Belfast Blitz were two of the heaviest of all bombings by the Luftwaffe, killing 568–1,000 civilians of Coventry, killing over 1,100 civilians in Belfast, and destroying much of both city centres.
British bombing policy evolved during the war. In the beginning, the RAF was forbidden to attack urban targets in Germany due to the risk of accidental civilian casualties. Following a German attack on military targets in the Orkney Islands on 16 March 1940 that killed a civilian, the RAF mounted an attack on the seaplane base on the island of Sylt. The RAF began attacking transport targets west of the Rhine on the night of 10 May following the German invasion of the Low Countries, and military targets in the rest of Germany after the bombing of Rotterdam. On 9 September 1940 RAF crews were instructed that due to the "indiscriminate" nature of German bombing, if they failed to find their assigned targets they were to attack targets of opportunity rather than bring their bombs home. On the 15/16 December the RAF carried out its first area bombing attack (destroying 45% of the city of Mannheim), officially in response to the raid on Coventry.
In 1942, the goals of the British attacks were defined: the primary goal was the so-called "morale bombing", to weaken the will of the civil population to resist. Following this directive intensive bombing of highly populated city centers and working class quarters started. On 30 May 1942, the RAF Bomber Command launched the first "1,000 bomber raid" when 1,046 aircraft bombed Cologne in Operation Millennium, dropping over 2,000 tons of high explosive and incendiaries on the medieval town and burning it from end to end. 411 civilians and 85 combatants were killed, more than 130,000 had to leave the city.
Two further 1,000 bomber raids were executed over Essen and Bremen, but to less effect than the destruction at Cologne. The effects of the massive raids using a combination of blockbuster bombs and incendiaries created firestorms in some cites. The most extreme examples were caused by the bombing of Hamburg in Operation Gomorrah (45,000 dead), and the bombings of Kassel (10,000 dead), Darmstadt (12,500 dead), Pforzheim (21,200 dead), Swinemuende (23,000 dead), and Dresden (25,000 dead).
The Allies also bombed urban areas in the other countries, including occupied France (Caen) and the major industrial cities of northern Italy, like Milan and Turin. Some cities were bombed at the different times by the Luftwaffe and the Allies, for example Belgrade in Yugoslavia and Bucharest in Romania.
The Luftwaffe also bombed cities in the Soviet Union, destroying Stalingrad in a massive air raid at the start of the Battle of Stalingrad and bombing Leningrad during the siege of the city of 1941–1943. The Soviet bombing of the German cities was limited in comparison with the RAF bombing (destruction caused by the Soviet army was mainly due to the land artillery). The Soviet Air Force also bombed Budapest in Hungary.
Asiatic-Pacific Theater.
In the Asiatic-Pacific Theater, Japan continued to bomb Chinese cities and expanded its air operations towards others in Asia such as Singapore, Rangoon, and Mandalay. In the first few months of the war with the Western Powers, Japan projected its airpower on settlements as distant as Honolulu, Darwin, and Unalaska.
The capture of the Mariana Islands in 1944 enabled the United States Army Air Forces to reach the Japanese home islands using the Boeing B-29 Superfortress. The U.S. firebombed Tokyo on the night of March 9–10, 1945, and killed more than 100,000 people in the deadliest conventional bombing in history, known as "Operation Meetinghouse". In a few hours, 100,000 people who were in Tokyo including civilians died either by the bombing or the conflagration that followed the bombing by 325 B-29's night attacks. The bombing was meant to burn wooden buildings and indeed the bombing caused fire that created a 50 m/s wind that is comparable to tornadoes. A total of 381,300 bombs amounting to 1783 tons, were used in the bombing.
After the successful "Operation Meetinghouse" raid, the USAAF went on to firebomb other Japanese cities in effort