From Air Force Magazine:
In October 1939, one month after war erupted in Europe, FDR directed the Army to study the matter.
In late July, President Truman warned the Japanese they must surrender or face terrible consequences. They ignored him. On Aug. 2, Tibbets received orders to drop the bomb. The Enola Gay took off from Tinian at 2:30 a.m., Aug. 6, 1945. The flight en route was uneventful, and at 8:15 a.m. the bomb exploded above Hiroshima at an altitude of 1,890 feet to maximize the blast effect.
Vice Adm. William H. P. Blandy was the overall commander for Crossroads, with Maj. Gen. William E. Kepner, from the AAF, as his deputy, and Brig. Gen. Roger M. Ramey leading the AAF contingent of 2,200 people.
One naval officer at Bikini commented that the Navy was much chastened by the tests. It had expected to sail the target fleet back to San Francisco to demonstrate the negligible effects atomic weapons had against it, but the radioactivity on the ships was so severe that the Navy abandoned the plan and sank the fleet—the contamination could not be removed despite countless attempts to do so.
In hindsight, it is apparent there was a great deal of institutional jealousy and gamesmanship being played by the atomic gatekeepers. The bomb’s assembly and arming, as well as the modifications carried out on the B-29s used for delivery, were not as complex as pretended. Moreover, secrecy was hardly airtight—the Soviets infiltrated the Manhattan Project early in the war and spies passed on invaluable secrets to Moscow.
Early Atomic Air
The airmen charged with delivering nuclear weapons were often kept in the dark about the revolutionary weapons.
Theoretically, it had been known for decades that splitting the atom would release enormous power—far greater than any explosive ever invented. In the 1930s the theories of nuclear fission began to take definite shape as scientists in Germany, the US, and elsewhere began experiments that revealed the secrets of the atom.
In early 1939 it was apparent war was coming in Europe. It was also obvious to a group of scientists in America, some of whom had recently fled Germany, that the Nazis were working toward an atomic bomb. This was a frightening possibility, so these individuals, led by Albert Einstein, wrote to President Franklin D. Roosevelt, warning him of the peril represented by German research. The US needed to beat the Nazis to the atomic bomb, and it would take immediate action and vast funds to do so.
509th Composite Group aircraft on Tinian, before its bombing mission to Hiroshima. Enola Gay is in the foreground. (Photo from the collection of Harold Agnew )
For the next six years the Army managed the Manhattan Project to build an atomic bomb. This was the most secretive weapon-development program of the war. The entire project was enormous, requiring not only covert laboratories, "heavy water" plants, and vast amounts of silver to produce the required electrical coils, but also mining operations to obtain the necessary uranium.
On Dec. 2, 1942, a team of scientists led by Nobel Prize winner Enrico Fermi huddled in a secret lab beneath the stands of the abandoned football stadium at the University of Chicago and produced the world’s first self-sustaining nuclear reaction. A year later scientists at Los Alamos, N.M., under the leadership of J. Robert Oppenheimer, began building a weapon from Fermi’s achievement. On July 16, 1945, an atomic device was detonated at Trinity Site in the New Mexico desert. The blast was seen as far away as Albuquerque and El Paso and entailed the now familiar ball of fire and mushroom cloud. One observer described the blast as "unprecedented, magnificent, beautiful, stupendous, and terrifying."
Ending the War
President Harry Truman was in Potsdam, discussing the postwar settlement of Germany with Joseph Stalin and British Prime Minister Clement Attlee, when he was told of the Trinity blast. According to Truman, there was never any question in his mind that he would use the atomic bomb against Japan. The issues now dealt with delivery and the appropriate target.
Because of its size and weight, the bomb could only be carried in a B-29; even so, the bombers had to be specially modified and the crews specially trained to handle the new weapon. In the summer of 1944, Gen. Henry H. "Hap" Arnold chose Lt. Col. Paul W. Tibbets Jr., a superb pilot with a distinguished combat record, to head the unit that would deliver the bomb. The 509th Composite Group was activated on Dec. 17, 1944, and after training in the US, Tibbets moved his unit to the island of Tinian in the Marianas. After undergoing normal theater orientation, the 509th flew a number of combat missions against Japan, utilizing large conventional bombs, termed "pumpkins," that resembled the atomic bombs in size, shape, and weight.
The target question involved several factors. President Truman and his advisors decided to hit an actual military target, rather than attempt a demonstration, such as exploding a bomb off the coast of Tokyo. There were too few bombs available to waste on empty space. It was also feared that since the actual bomb had not yet been tested—Trinity was a huge, static device detonated under laboratory conditions—the psychological and propaganda harm of announcing a demonstration only to have the bomb fail to explode was too great a risk.
This concern was not trivial; even the head of the Joint Chiefs of Staff, Fleet Adm. William D. Leahy (who considered himself an ordnance expert), predicted failure.
In addition, military planners and scientists wanted an untouched target so they could more easily determine the effects of the atomic blast. Secretary of War Henry L. Stimson then crossed Kyoto off the target list because of its historical and cultural significance. The name then coming out on top was Hiroshima—Japan’s eighth largest city, a large seaport, headquarters of the Second Army, and a major war industry center.
Enola Gay crewmembers (l-r) Maj. Theodore Van Kirk, Col. Paul Tibbets Jr., and Maj. Thomas Ferebee. Despite their successful mission over Hiroshima, Tibbets’ crew was bypassed for the tests at Bikini Atoll.
The bomb, termed "Little Boy," had a uranium core and detonated with the equivalent force of 20,000 tons of TNT—equal to thousands of B-29s carrying conventional bombs. Tibbets described the blast as a "giant purple mushroom" that quickly rose to a height of 45,000 feet—three miles higher than the aircraft’s own altitude—and even from several miles away appeared to be "boiling upward like something terribly alive." It gave the unsettling appearance of a phenomenon about to engulf the airplane. In the city below, it destroyed virtually everything within a one-mile radius of the blast.
A second bomb, a more advanced plutonium design nicknamed "Fat Man," was dropped on Nagasaki on Aug. 9. Japan surrendered five days later.
Debate still rages over whether the atomic bombs were necessary to force Japanese surrender, but it was not a serious question at the time. Truman had no regrets over his decision—the invasion of Japan scheduled for November could have cost millions of lives, on both sides. He was not willing to pay that price. Japanese leaders interviewed after the war agreed the bombs had been the final straw that had broken their will. The enormous power of the atomic bombs had as much psychological effect as it did physical. Essentially, everyone believed atomic weapons had fundamentally altered the conduct of war. There would have to be new strategies, new weapons, new organizations, and new doctrines.
When the war ended the Army Air Forces shrank dramatically in size, as did the entire military establishment. The AAF, which had consisted of 243 groups in March 1945, quickly dropped by two-thirds—it would eventually bottom out at 48 groups—and many of those were no longer combat-ready. The 509th was one of the few groups still in good shape, and it formed the core of the "atomic air force."
Besides demobilization and budget cutbacks, the AAF faced the problem of secrecy. The Manhattan Engineer District run by Maj. Gen. Leslie R. Groves was a very close-hold organization. For the airmen, this was a major concern. Their institutional future seemed dependent on atomic weapons, but they had virtually no insight into the bomb’s development or production. It made them a bit paranoid.
The Bikini Atomic Tests
On Aug. 25, 1945, Sen. Brien O. McMahon, chairman of the Senate’s Special Committee on Atomic Energy, suggested taking captured Japanese and German ships out to sea and bombing them with atomic weapons to prove "just how effective the atomic bomb is." The Joint Chiefs agreed, and in January 1946, Acting Secretary of War Kenneth C. Royall and Navy Secretary James V. Forrestal sent a memo to the President emphasizing such tests were necessary "to determine, among other things, the consequences of this powerful aerial weapon with respect to the size, composition, and employment of the armed forces and should particularly facilitate an analysis of future naval design and tactics."
Truman approved tests to be carried out at Bikini Atoll in the Pacific; their code name was Crossroads.
The Army and Navy would jointly conduct these atomic tests because the main targets were to be surplus American ships and captured enemy vessels. The plan called for one air burst over the ships themselves—to be dropped by a B-29 from the 509th—and two underwater detonations arranged by the Navy. (During the event, only one underwater detonation took place because the first was so successful.)
Seated at the Potsdam Conference (l-r): British Prime Minister Clement Attlee, US President Harry Truman, and Soviet Premier Joseph Stalin. Truman learned of the successful Trinity test while at this conference.
The first test, termed Able, was scheduled for July 1. The 509th had been practicing in New Mexico for several months, dropping "pumpkin" dummy bombs in the desert. Accuracy remained a concern. The horrible aerodynamic shape of the 10-foot-long, five-foot-diameter, and 10,000-pound Fat Man bombs had been troublesome since Nagasaki, but little had been done to correct it. Nonetheless, the crews felt confident as they prepared for the trip out to the Marshall Islands.
Crews from the 509th dropped 27 practice bombs on the target to refine their skills. Even so, it appeared trouble was brewing when Kepner received a memo stating, "The scoring system, which worked so well in the States, seems to be giving trouble at Bikini. Of the seven releases, it was possible to measure the accuracy of only four, and those were estimated."
According to the practice scores obtained, Tibbets’ crew was the best. Nonetheless, he was bypassed as mission pilot because of what he later claimed was internal Air Force politics.
On the day of the drop, Tibbets and two of his bombardiers noted the winds and computed when and where to drop the bomb. Their calculations were far different from those of the assigned drop crew. Tibbets offered suggestions to the chosen crew but they ignored him: One of Tibbets’ bombardiers, Maj. Thomas Ferebee, predicted the bomb would fall 1,600 feet short and to the left of the target.
On the morning of July 1, 1946, a B-29 arrived over USS Nevada—painted bright red so as to be visible from 30,000 feet—and dropped its bomb. The device was to explode 550 feet over the top of the battleship and sink it immediately. It detonated at 518 feet, but it missed its target by nearly half a mile, and to the left—as Ferebee had predicted. Despite months of practice and two dry runs immediately before the actual drop, the bomb still missed its target, in perfect weather, by more than five football fields.
The Navy was much amused. Nevada was still afloat—although five other ships were sunk and others were heavily damaged. As an aircraft approached the barely scorched Nevada, one sailor mused: "Well, it looks to me like the atom bomb is just about like the Army Air Force [sic]—highly overrated."
What Had Gone Wrong?
People pointed fingers at the aircrew, airplane, bombsight, and the bomb itself. Maj. Gen. Curtis E. LeMay, the deputy chief of the air staff for research and development, ordered tests of the aircraft and bombsight immediately thereafter, but they showed no malfunction. Crew error was also ruled out, although as noted, some believed that was the culprit. The Strategic Air Command official history blamed unpredictable winds.
One report of the incident concluded lamely that "some unusual force affected the bomb, causing it to veer off in an unpredictable and erratic manner, giving a point of impact somewhere left and short of the theoretical one." One theory was that a bomb fin was damaged on leaving the aircraft and this caused the weapon to veer off course.
The AAF blamed the poor aerodynamics of Fat Man and used this as an argument for greater transparency in the atomic weapons program. If the AAF were to be responsible for dropping the bombs in war, then it should have greater insight into their construction. Divided authority over development and delivery was a recipe for disaster.
In the aftermath, the AAF continued to hammer away at Groves in an attempt to gain more access to the atomic program. By late 1946 an agreement was reached: Groves would train more bomb commanders—air officers who would assemble the bombs—as well as weaponeers to actually monitor the weapon in flight. This was a major step forward. At the same time, despite the embarrassment of the errant bomb, the test gave the services and policy-makers an opportunity to witness the power of the new weapon. Many found this sobering.
Lt. Gen. Henry "Hap" Arnold (r) with Col. Jacob Smart in China. Arnold picked Tibbets to head the 509th Composite Group.
This was, as the naval observer noted, "a momentous decision, a momentous admission." The official committee tasked to examine the results of Crossroads painted the significance of the atomic bomb in stark terms: "If used in numbers, atomic bombs not only can nullify any nation’s military efforts, but can demolish its social and economic structure and prevent their re-establishment for long periods of time." The report went on to state there was no defense against the bomb; therefore the US could only stockpile enough weapons so it could overwhelm any potential enemy.
Atomic weapon development, which took all but the most senior diplomats and military officers by surprise, is recognized as a defining moment in history. The detonation of a single bomb carried by one aircraft that destroyed a large portion of a major city while killing tens of thousands of people had a profound psychological effect on everyone.
Cities and people had been destroyed before—the Romans leveled Carthage in antiquity and 50,000 Roman soldiers had been slaughtered in one afternoon at the Battle of Cannae—but the impact of such destruction occurring nearly instantaneously by such a relatively small device shook the foundations of military theory.
Gen. Carl A. Spaatz, the Commanding General of the AAF, noted this belief when he wrote in April 1946: "Strategic bombing is thus the first war instrument of history capable of stopping the heart mechanism of a great industrialized enemy. It paralyzes his military power at the core."
Airmen believed this, and because initial atomic bombs were so large and cumbersome, only large aircraft could deliver them. Specially modified B-29s, then the largest aircraft in the world, were the sole carriers of the bomb, and they belonged to the AAF. This gave airmen a sense of both euphoria and paranoia. Although they owned the aircraft, they did not own the bombs. The Manhattan Engineer District controlled all aspects of atomic bomb development, construction, and assembly. In January 1947 the district was disbanded and its functions absorbed by the Atomic Energy Commission (AEC).
The cloak of secrecy draped over the program by Groves and then the AEC was so total that airmen were kept almost completely in the dark. Indeed, not just airmen were in this state: When the AEC briefed President Truman in April 1947, they told him the atomic stockpile was "very small." Worse, no bombs were actually assembled and few personnel were trained to do so. Truman, who had been President for two years by then and should have known better, was nonetheless visibly shocked. At that time, there were only 13 unassembled atomic bombs in the entire US arsenal.
The second of two Crossroads nuclear tests at Bikini Atoll in the Pacific in July 1946. Due to severe radioactive contamination, the Navy had to sink the fleet of ships used as targets in the two tests.
As early as 1942 Groves knew the Russians were attempting to infiltrate the Manhattan Project, but did little to stop them. In fact, one historian labeled the MED’s attempts at counterespionage as "amateurish." The heavy mantle of secrecy was successful largely in keeping information from the airmen charged with delivering the bomb, not from the Soviets.
Airmen would fight against this bureaucratic barricade for years. Not until the Korean War broke out, and there were fears of major conflict with the Soviet Union and China, did custody of atomic weapons finally transfer to the military—when atomic weapons were deployed to Guam just in case.
By the end of the decade, as a result of a decree by President Dwight Eisenhower, more than 90 percent of the nuclear stockpile had been transferred to the military. There it would remain.
Phillip S. Meilinger is a retired Air Force pilot with 30 years of service and a doctorate in military history from the University of Michigan. He is the author of eight books and more than 80 articles on military affairs. His latest book is Into the Sun: Novels of the US Air Force. His most recent article for Air Force Magazine, "How Bombers Defeated Japan," appeared in December 2011.