The Mark 36 was a second-generation hydrogen bomb. It weighed about half as much as the early thermonuclears—but 10 times more than the new, sealed-pit bombs that would soon be mass-produced for SAC [the Strategic Air Command]. It was a transitional weapon, mixing old technologies with new, featuring thermal batteries, a removable core, and a contact fuze for use against underground targets. The nose of the bomb contained piezoelectric crystals, and when the nose hit the ground, the crystals deformed, sending a signal to the X-unit, firing the detonators, and digging a very deep hole. The bomb had a yield of about 10 megatons. It was one of America’s most powerful weapons.

A B-47 bomber was taxiing down the runway at a SAC base in Sidi Slimane, Morocco, on January 31, 1958. The plane was on ground alert, practicing runway maneuvers, cocked but forbidden to take off. It carried a single Mark 36 bomb. To make the drill feel as realistic as possible, a nuclear core had been placed in the bomb’s in-flight insertion mechanism. When the B-47 reached a speed of about 20 miles an hour, one of the rear tires blew out. A fire started in the wheel well and quickly spread to the fuselage. The crew escaped without injury, but the plane split in two, completely engulfed in flames. Firefighters sprayed the burning wreckage for 10 minutes—long past the time factor of the Mark 36—then withdrew. The flames reached the bomb, and the commanding general at Sidi Slimane ordered that the base be evacuated immediately. Cars full of airmen and their families sped into the Moroccan desert, fearing a nuclear disaster.

The fire lasted for two and a half hours. The high explosives in the Mark 36 burned but didn’t detonate. According to an accident report, the hydrogen bomb and parts of the B-47 bomber melted into “a slab of slag material weighing approximately 8,000 pounds, approximately 6 to 8 feet wide and 12 to 15 feet in length with a thickness of 10 to 12 inches.” A jackhammer was used to break the slag into smaller pieces. The “particularly ‘hot’ pieces” were sealed in cans, and the rest of the radioactive slag was buried next to the runway. Sidi Slimane lacked the proper equipment to measure levels of contamination, and a number of airmen got plutonium dust on their shoes, spreading it not just to their car but also to another air base.

The Air Force planned to issue a press release about the accident, stressing that the aircraft fire hadn’t led to “explosion of the weapon, radiation, or other unexpected results.” The State Department thought that was a bad idea; details about the accident hadn’t reached Europe or the United States. “The less said about the Moroccan incident the better,” one State Department official argued at a meeting on how much information to disclose. A public statement might be distorted by Soviet propaganda and create needless anxiety in Europe. The Department of Defense agreed to keep the accident secret, although the king of Morocco was informed. When an American diplomat based in Paris asked for information about what had happened at Sidi Slimane, the State Department told him that the base commander had decided to stage a “practice evacuation.”

Two weeks after an accident that could have detonated a hydrogen bomb in Morocco, the Department of Defense and the Atomic Energy Commission issued a joint statement on weapon safety. “In reply to inquiries about hazards which may be involved in the movement of nuclear weapons,” they said, “it can be stated with assurance that the possibility of an accidental nuclear explosion . . . is so remote as to be negligible.”

Less than a month later, Walter Gregg and his son, Walter Junior, were in the toolshed outside their home in Mars Bluff, South Carolina, when a Mark 6 atomic bomb landed in the yard. Mrs. Gregg was inside the house, sewing, and her daughters, Helen and Frances, aged six and nine, were playing outdoors with a nine-year-old cousin. The Mark 6 had a variable yield of anywhere from 8 to 160 kilotons, depending on the type of nuclear core that was used. The bomb that landed in the yard didn’t contain a core. But the high explosives went off when the weapon hit the ground, digging a crater about 50 feet wide and 35 feet deep. The blast wave and flying debris knocked the doors off the Gregg house, blew out the windows, collapsed the roof, riddled the walls with holes, destroyed the new Chevrolet parked in the driveway, killed half a dozen chickens, and sent the family to the hospital with minor injuries.

The atom bomb had been dropped by a B-47 en route from Hunter Air Force Base near Savannah, Georgia, to Bruntingthorpe Air Base in Leicestershire, England. The locking pin had been removed from the bomb before takeoff, a standard operating procedure at SAC. Nuclear weapons were always unlocked from their bomb racks during takeoff and landing—in case the weapons had to be jettisoned during an emergency. But for the rest of the flight they were locked to the racks. Bombs were locked and unlocked remotely on the B-47, using a small lever in the cockpit. The lever was attached by a lanyard to the locking pin on the bomb. As the B-47 above South Carolina climbed to an altitude of about 15,000 feet, a light on the instrument panel said that the pin hadn’t reengaged. The lever didn’t seem to be working. The pilot told the navigator, Captain Bruce Kulka, to enter the bomb bay and insert the locking pin by hand.

Kulka couldn’t have been thrilled with the idea. The bomb bay wasn’t pressurized, the door leading to it was too small for him to enter wearing a parachute, and he didn’t know where the locking pin was located, let alone how to reinsert it. Kulka spent about 10 minutes in the bomb bay, looking for the pin, without success. It must be somewhere above the bomb, he thought. The Mark 6 was a large weapon, about 11 feet long and 5 feet in diameter, and as Kulka tried to peek above it, he inadvertently grabbed the manual bomb release for support. The Mark 6 suddenly dropped onto the bomb bay doors, and Kulka fell on top of it. A moment later, the 8,000-pound bomb broke through the doors. Kulka slid off it, got hold of something in the open bomb bay, and held on tight. Amid the gust and roar of the wind, about 3 miles above the small farms and cotton fields of Mars Bluff, he managed to pull himself back into the plane. Neither the pilot nor the copilot realized the bomb was gone until it hit the ground and exploded.

The accident at Mars Bluff was impossible to hide from the press. Although Walter Gregg and his family had no idea what destroyed their home, the pilot of the B-47, unable to communicate with Hunter Air Force Base, told controllers at a nearby civilian airport that the plane had just lost a “device.” News of the explosion quickly spread. The state police formed checkpoints to keep people away from the Gregg property, and an Air Force decontamination team arrived to search for remnants of the Mark 6. Unlike the accident at Sidi Slimane, this one couldn’t have produced a nuclear yield—and yet it gained worldwide attention and inspired a good deal of fear. “Are We Safe from Our Own Atomic Bombs?” the New York Times asked. “Is Carolina on Your Mind?” echoed London’s Daily Mail. The Soviet Union claimed that a nuclear detonation had been prevented by “sheer luck” and that South Carolina had been contaminated by radioactive fallout.

The Strategic Air Command tried to counter the Soviet propaganda with the truth: there’d never been a risk of nuclear detonation, nor of harmful radioactivity. But SAC also misled reporters. During a segment entitled “‘Dead’ A-Bomb Hits US Town,” Ed Herlihy, the narrator of a popular American newsreel, repeated the official line, telling nervous movie audiences that this was “the first accident of its kind in history.” In fact, a hydrogen bomb had been mistakenly released over Albuquerque the previous year. Knocked off balance by air turbulence while standing in the bomb bay of a B-36, the plane’s navigator had steadied himself by grabbing the nearest handle—the manual bomb release. The weapon broke through the bomb doors, and the navigator held onto the handle for dear life. The H-bomb landed in an unpopulated area, about one third of a mile from Sandia. The high explosives detonated but did not produce a nuclear yield. The weapon lacked a core.

The Air Force grounded all its bombers after the accident at Mars Bluff and announced a new policy: the locking pins wouldn’t be removed from nuclear weapons during peacetime flights. But the announcement failed to dampen a growing antinuclear movement in Great Britain. [SAC commander] General [Thomas S.] Power had inflamed public opinion by telling a British journalist, who’d asked whether American aircraft routinely flew with nuclear weapons above England, “Well, we did not build these bombers to carry crushed rose petals.” Members of the opposition Labour Party criticized Prime Minister Harold Macmillan for allowing such flights and demanded an end to them. Macmillan was in a difficult position. For security reasons, SAC wouldn’t allow him to reveal that the bombs lacked cores—and wouldn’t even let him know when American planes were carrying nuclear weapons in British airspace.

Within weeks of the accident at Mars Bluff, a newly formed organization, the Campaign for Nuclear Disarmament (CND), led thousands of people on a protest march from London’s Trafalgar Square to the British nuclear weapon factory at Aldermaston. The CND rejected the whole concept of nuclear deterrence and argued that nuclear weapons were “morally wrong.” In preparation for the four-day march, the artist Gerald Holtom designed a symbol for the antinuclear movement. “I drew myself,” Holtom recalled, “the representative of an individual in despair, with palms outstretched outwards and downwards in the manner of Goya’s peasant before the firing squad.” He placed a circle around the self-portrait, an elongated stick figure, and created an image later known as the peace sign.

The Soviet Union worked hard to focus attention on the dangers of SAC’s airborne alert and the possibility of an accidental nuclear war. “Imagine that one of the airmen may, even without any evil intent but through nervous mental derangement or an incorrectly understood order, drop his deadly load on the territory of some country,” Khrushchev said during a speech. “Then according to the logic of war, an immediate counterblow will follow.” Arkady A. Sobolev, the Soviet representative to the United Nations, made a similar argument before the Security Council, warning that the “world has yet to see a foolproof system” and that “flights of American bombers bring a grave danger of atomic war.” The Soviet concerns may have been sincere. But they also promoted the idea that American bombers were the greatest threat to world peace—not the hundreds of Soviet medium-range missiles aimed at the capitals of Western Europe. Bertrand Russell, among others, had changed his view about whom to blame. Having once called for the United States to launch a preventive war on the Soviet Union with atomic bombs, Russell now argued that the American air bases in England should be shut down and that Great Britain should unilaterally get rid of its nuclear weapons.

The mental instability of SAC officers became a recurrent theme in Soviet propaganda. According to a Pentagon report obtained by an East German newspaper and discussed at length on Radio Moscow, 67.3 percent of the flight personnel in the United States Air Force were psychoneurotic. The report was a Communist forgery. But its bureaucratic tone, its account of widespread alcoholism, sexual perversion, opium addiction, and marijuana use at SAC, seemed convincing to many Europeans worried about American nuclear strategy. And the notion that a madman could deliberately start a world war became plausible, not long after the forgery appeared, when an American mechanic stole a B-45 bomber from Alconbury Air Force Base in England and took it for a joyride. The mechanic, who’d never received flight training, crashed the jet not long after takeoff and died.

A former Royal Air Force officer, Peter George, captured the new zeitgeist about nuclear weapons, the widespread fear of an accidental war, in a novel published amid the debate over SAC’s airborne alert. Pulp fiction like One of Our H Bombs Is Missing had already addressed some of these themes. But more than 250,000 copies of George’s novel Red Alert were sold in the United States, and it subsequently inspired a classic Hollywood film. Writing under the pseudonym “Peter Bryant,” George described how a deranged American general could single-handedly launch a nuclear attack. The madman’s views were similar to those expressed by Bertrand Russell a decade earlier: the United States must destroy the Soviet Union before it can destroy the West. “A few will suffer,” the general believes, “but millions will live.”

Once the scheme is uncovered, the general’s air base is assaulted by the US Army. The president of the United States tries without success to recall SAC’s bombers, and the Soviets question whether the impending attack really was a mistake. As an act of good faith, SAC discloses the flight paths of its B-52s so that they can be shot down. After negotiations between the leaders of the two nations and revelations about “the ultimate deterrent”— doomsday weapons capable of eliminating life on earth, to be triggered if the Soviets are facing defeat—all but one of the SAC bombers are shot down or recalled. And so a deal is struck: if the plane destroys a Soviet city, the president will select an American city for the Soviets to destroy in retaliation. The president chooses Atlantic City, New Jersey. The lone B-52 drops its hydrogen bomb over the Soviet Union—but the weapon misfires and misses its target. Although Atlantic City is saved and doomsday averted, Red Alert marked an important cultural shift. The Strategic Air Command would increasingly be portrayed as a refuge for lunatics and warmongers, not as the kind of place where you’d find Jimmy Stewart.

General Power was unfazed by protest marches in Great Britain, apocalyptic fears, criticism in the press, freak accidents, strong opposition at the AEC [the Atomic Energy Commission], Eisenhower’s reluctance, and even doubts about the idea expressed by [former SAC commander General Curtis] LeMay. Power wanted an airborne alert. The decision to authorize one would be made by President Eisenhower. The phrase “fail safe” had been removed from Air Force descriptions of the plan. The word “fail” had the wrong connotations, and the new term didn’t sound so negative: “positive control.” With strong backing from members of Congress, SAC proposed a test of the airborne alert. B-52s would take off from bases throughout America, carrying sealed-pit weapons. At a White House briefing in July 1958, Eisenhower was told that “the probability of any nuclear detonation during a crash is essentially zero.” The following month, he gave tentative approval for the test. But the new chairman of the AEC, John A. McCone, wanted to limit its scale. McCone thought that the bombers should be permitted to use only Loring Air Force Base in Maine—so that an accident or the jettison of a weapon would be likely to occur over the Atlantic Ocean, not the United States. During the first week of October, President Eisenhower authorized SAC to take off and land at Loring, with fully assembled hydrogen bombs. The flights secretly began, and SAC’s airborne alert was no longer a bluff.

Editor's note: This article is excerpted from the book Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety. An interview with Eric Schlosser, the book’s author, appears in the March/April issue of the Bulletin. Reprinted by arrangement with The Penguin Press, a member of Penguin Group (USA) LLC, A Penguin Random House Company. Copyright ©Eric Schlosser, 2013.