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The U.S. Army’s unique, 85-ton artillery launcher could certainly shoot, but could it really scoot?

CAMP DESERT ROCK, in the Frenchman Flat area of the Nevada Test Site, was warm and bustling with activity when dawn broke on May 25, 1953. The occa­sion was the 10th “shot” in a series of 11 nu­clear tests in Operation Upshot­-Knothole, conducted in conjunction with Desert Rock V, a readiness exercise designed to train American troops to fight on a nuclear battlefield. The tests included three atomic bombs dropped from aircraft, seven bombs detonated from towers—and a first-­of-­its-­kind nuclear test, designated Grable.

About 3,000 visitors had arrived at Camp Desert Rock to observe the Grable test shot—congressmen, high-ranking military officers, top officials from the Atomic Energy Commission, and other government agencies, plus more than 100 reporters. While preparations for the test proceeded, Secretary of Defense Charles Wilson and Admiral Arthur Radford, the designated chairman of the Joint Chiefs of Staff, made their way to the viewing area, roughly 10 miles from ground zero. All had come to witness the first atomic shell ever fired from a U.S. Army cannon—the first nuclear artillery piece in the world.

Atomic artillery seems like a quixotic idea now, but the Cold War rivalry between the United States and the Soviet Union in the 1950s was real and provoked all sorts of military machinations. Until this Nevada atomic test, the Air Force had claimed dominion over America’s nuclear arsenal—but the army, worried about a Soviet invasion of Western Europe, convinced the Pentagon that it needed a tactical nuclear weapon. It got one: a massive cannon, whimsically named “Atomic Annie,” that was designed to wipe out advancing enemy divisions more than 20 miles away with an atomic shell packing the same explosive power as the “Little Boy” bomb that had destroyed Hiroshima eight years earlier. The atomic cannon was the largest and most powerful mobile weapon ever deployed by the U.S. Army. Now, the question was: Would it work?


AT THE PROVING GROUNDS, a briefing officer explained for observers why the U.S. Army believed it needed a mobile nuclear launcher. At the end of World War II in 1945, The United States and most other nations demobilized their huge wartime armed forces. But the Soviet Union did not demobilize. Soviet premier Josef Stalin reorganized the massive Red Army and equipped it with new tanks, guns, aircraft, and naval vessels. Meanwhile, the occupied nations of Eastern Europe were forced to establish communist governments and build armies to support the Soviet Union and its aggressive plans for communist expansion, a strategic development that prompted former British prime minister Winston Churchill’s famous March 5, 1946, speech in Fulton, Missouri: “From Stettin in the Baltic to Trieste in the Adriatic, an iron curtain has descended across the Continent.”

When the Soviet Union cut off supplies to Berlin on June 24, 1948, any hopes for a peaceful postwar Europe were dashed. The United States and Great Britain responded with a massive airlift of food, coal, and other goods into the city before Stalin on May 12, 1949, lifted the Berlin blockade. By then there was no doubting the Soviet threat to Western Europe.

Pentagon war planners knew that any Soviet invasion of Western Europe would begin with surprise air strikes against U.S. and Allied air bases. Once tactical air forces were neutralized, the huge Soviet armored and mechanized armies could overrun U.S. and NATO ground forces. The North Atlantic Treaty Organization had been established in April 1949 to strengthen and coordinate a conventional defense against a Soviet invasion. The real deterrent to any attack by the Warsaw Pact nations, however, would be American nuclear capability. But that was problematic: Though the U.S. Air Force feet of long-­range bombers, including the Convair B­36 armed with nuclear bombs, was formidable, it was based in the United States and might not be able to act fast enough to stem a frontal assault.

The Soviets further jangled American nerves when they exploded their first atomic bomb on August 29, 1949. With the military stakes rising, Congress that year approved the development of small tactical nuclear weapons for the air force, and the Department of Defense agreed that the army needed a nuclear capability of its own—a weapon that could be dispersed and thus was less vulnerable to surprise attack. The army focused on mobile artillery as a means of delivering a nuclear warhead. Surface­-to-­surface guided missiles with nuclear warheads were being developed, but they were years away from deployment.


WHAT ARTILLERY PIECE could deliver a nuclear warhead? Since World War II the army had been developing a large, 240mm (9.5­inch) mobile cannon, one that could fire a conventional high­-explosive, spotter, or—eventually—a nuclear projectile to a target several miles away with near pinpoint accuracy, something fighter-­bombers of the period could not achieve. But the 240mm gun was too small to handle the smallest existing atomic warhead, so in November 1949 the order was given to build a new cannon, based mainly on previous design work, that could fire a 280mm (11­inch) nuclear projectile then in development—the T­124 with a W9 warhead—with a longer range than its predecessor. Robert Schwartz, an engineer with the Picatinny Arsenal in New Jersey, created the preliminary designs in only 15 days.

The design of the gun and its carriage were influenced by the German 280mm K5 (E) railway gun, which had shelled American troops on the Anzio beachhead before being captured in Italy in 1944. Members of the Picatinny design team visited Aberdeen Proving Ground, in Maryland, to examine the K5, which in the United States had been dubbed “Anzio Annie.” That seems to be why the atomic cannon eventually was named Atomic Annie. Twenty guns were ordered—and with the start of the Korean War on June 25, 1950, the development of the 280mm cannon, designated the T131, was accelerated. The carriages were made at the Army’s Watertown Arsenal in Massachusetts, and the gun tubes and breeches were made and assembled at its Watervliet Arsenal in New York.

The atomic cannon consisted of three main parts: the gun, its carriage, and the transporter. Other than its size, the gun was of rather conventional design, as was its ammunition. But the nuclear ammunition and the T10 transporter were new, unique designs. The gun had a muzzle velocity of 2,060 feet per second, a range of 18.6 miles, elevation of 0 to 55 degrees, and traverse of 360 degrees. The gun could be fired electrically from a distance or by a lanyard. The weapon’s overall length, including transporter, was 84 feet 2 inches—and the complete unit weighed 85 tons. It required a crew of 27 men, plus support vehicles.

Moving this hulking artillery piece was a serious challenge. The transporter, which comprised two specially designed cabs, or tractors, picked up the gun and carriage and lodged them between the two vehicles. Each tractor had independent steering, forward or backward, similar to that of extra­long fire engines. When in transit, the forward tractor controlled the throttle and brakes for both units. The somewhat awkward combination could reach 35 miles an hour and negotiate right turns on roads at least 28 feet wide. The weapon could even move sideways by turning the tractors at right angles to the center section. The transporter had its own hydraulic system for lifting the gun into its traveling position and lowering it to firing position on the ground. A generator supplied the power to ram the projectile and separate bagged powder charges into the breech.


THE ATOMIC ANNIE PROTOTYPE was completed in the spring of 1951, and that autumn it and two other test cannons were taken to Aberdeen Proving Ground for initial test firing with conventional ammunition. The first gun was later moved to the Army Artillery Center at Fort Sill, Oklahoma, where a specially formed Artillery Test Unit of the 867th Field Artillery Battalion spent a year training with it, firing on the range with conventional ammunition and spotter and dummy nuclear rounds, and obtaining vital information on various firing techniques. Crew duties were defined, firing tables were confirmed, and experience gained in the operation of the gun.

Technicians from the Atomic Energy Commission, which at the time controlled nuclear munitions, trained crewmen to safely handle the nuclear ammunition. All soldiers assigned to nuclear munitions units were issued dosimeters, and the AEC established the limits of ionizing radiation for soldiers. The army later issued pen­-type dosimeters that could more accurately measure the cumulative exposure to radiation. Dosimeters were examined periodically, and any crewman who had reached his maximum exposure level was transferred out of the unit.

The nuclear ammunition developed for the atomic cannon was a marvel of miniaturization. The first atomic projectile was designed initially by Robert Schwartz and developed in cooperation with scientists from the AEC’s Los Alamos and Sandia Laboratories. The first shell, the T­124 with W9 nuclear warhead, was only 541 inches long, 11 inches in diameter, and weighed 803 pounds—far smaller than the Mk 1 Little Boy but with the same explosive power.

Because the nuclear warhead would be subjected to an unprecedented jolt when fired at 2,060 feet per second, the cannon’s stability was paramount. The shooting mechanism had an absolute minimum of moving parts, all mounted securely to resist shock. What’s more, the reliability of the nuclear shells had to be far higher than conventional ammunition to prevent accidents and keep unexploded projectiles from falling into enemy hands.

The atomic cannon entered production in 1952, and on January 20, 1953, one Atomic Annie, on its transporter, trundled through the streets of Washington, D.C., as part of the inaugural parade for President Dwight D. Eisenhower.


AT THE TEST SITE at Frenchman Flat, Atomic Annie and a backup M65 cannon were brought in, removed from their transporters, and placed in firing positions. Atomic Annie was situated on ground high enough to be in direct line of sight to ground zero. (This would have been an impractical location for the gun in combat but was necessary for the test for technical and instrumentation reasons). Several adjustment and registration (spotting) rounds were fired at the so-­called air zero point, about seven miles away, to zero-­in the gun. The chief of section (gun captain) signaled that Annie was ready to fire a live atomic shell. Meteorologists again checked the wind direction, and the thousands of troops on the simulated nuclear battlefield were ordered to take cover in trenches and bunkers and shield their eyes.

The gun crew felt confident but nervous when they received the order to prepare for firing. AEC technicians removed the T­124 shell from its container, and uranium­235 components along with the fuze were inserted into the W9 warhead. One of three time­-altitude settings was chosen, and Lieutenant Colonel Donald L. Harrison of the Artillery School made a final check of defections, quadrant, and fuze settings. A crane truck raised the warhead, and it was rammed into the breech, followed by the powder charges. The breech was sealed.

The gun crew, who had received the firing commands by telephone and radio, then withdrew and took cover in a nearby trench and waited for the order to fire the gun remotely. H­-hour was scheduled for 8:30 a.m. The 700 VIPs and the rest of the observers in the bleachers, about three miles from the gun and 10 miles from ground zero, adjusted their dark lens goggles and followed the final countdown on the PA system: Ten, nine, eight, seven, six… Those in charge grew tense: Would the gun function and the shell explode on target, or could there be a catastrophic accident?…. Five, four, three, two, one, FIRE!

KABOOM! At 8:30 a.m., a cloud of dust billowed up around the gun, smoke belched from the barrel, and the atomic shell soared away. “I had the task of physically ramming out the atomic shell in case of a misfire,” said Colonel Harrison. “So I gave a big sigh of relief when the activated atomic round cleared the tube with only the big shell’s normal thunderous noise.” The crew waited anxiously as 19.2 seconds ticked by—and then came the word: The 15 kiloton shell had exploded as planned, 524 feet over ground zero. Everyone cheered.

The flash and fireball, many times brighter than the sun, was a fearsome sight. Smoke and radioactive debris erupted into the sky and rapidly rose in a great mushroom-­shaped cloud that rose to 38,000 feet. Less than a minute later, a destructive shockwave, moving faster than sound, was felt 10 miles away. A second blast wave followed—and then came the noise. The VIPs, scientists and observers were mostly quiet as they left the viewing area. Theirs was an experience never to be forgotten.

The Atomic Annie crew was ecstatic—and relieved. The gun had functioned normally. The success of the test was trumpeted worldwide: Here was a new delivery system that would expand the army’s tactical options. Representative W. Sterling Cole of New York, chairman of the Joint Congressional Committee on Atomic Energy, said: “In order to understand the military importance of our progress, one has to recall that the 1945 bomb was so big as to require a four-­engine B­29 bomber to carry it to Hiroshima. The projectile fred in today’s test was just over 11 inches in diameter. They have concentrated into capsule form what once filled an entire bomb bay.”


ATOMIC ANNIE AND HER SIBLINGS were ready for deployment. At Fort Sill, atomic combat crews were organized and trained—the 264th, 265th, 867th, and 868th Field Artillery Battalions. As the guns arrived, one or two were assigned to each battery. In November 1953, Atomic Annie was assigned to the 265th Field Artillery Battalion and deployed in Germany. Another atomic artillery battalion was sent to South Korea. (According to the 1994 book Westmoreland, by Samuel Zafri, President Eisenhower warned the Chinese that if the deadlock of the Korean War peace talks in Panmunjom was not broken, he was going to use tactical nuclear weapons against their army in Korea to end the war.) Since deterrence was a primary objective, the assignment of the atomic artillery units to Europe was not kept secret, although their exact locations were.

The 265th soon began an intense training period in the vicinity of U.S. bases in Grafenwöhr and Baumholder, Germany. The guns, with their convoy of support vehicles, were moved through German villages to ranges where they practiced firing live shells and dummy nuclear rounds. The locals were not amused. According to James I. Miller, commander of Battery C of the 265th Field Artillery Battalion: “Farmers blamed us for chickens not laying eggs and cows not giving milk, and even said that the shells prevented women from getting pregnant. It took much explaining to satisfy everyone that the rounds were standard high explosive and not the feared atomic shells.”

There was a far more serious problem than local unease. The “mobile” atomic cannon actually wasn’t very mobile after all. The training emphasized “shoot and scoot” to a hiding place, such as a large barn, to preclude detection. But the transporter was tricky to drive and could not “scoot.” Lieutenant Colonel James L. Tompson of the 265th said that while the transporters could maneuver on hard surfaces, they were “highly immobile” on any other type of road, especially muddy or icy surfaces or rough terrain. “You can imagine the anxiety of moving that tonnage through the darkness of a black night on mud­-slicked or soft terrain,” he said. What’s more, the crew had to ensure that bridges could support the weight of the gun. Essentially, the cannon’s size would have made it difficult to evacuate, after firing a shot, to avoid enemy counterbattery fire or an air strike. “The gun could not be lifted from its firing position to the transporters on even slightly uneven ground,” said Tompson.

The Soviet Union, meanwhile, was developing its own nuclear ammunition and artillery, and encountering the same difficulties. Nikita Khrushchev stated in his memoirs that after the U.S. atomic cannon arrived in Europe, an atomic cannon was developed for the Soviet Army—believed to have been either the M1957 310mm self­-propelled gun or the M1957 420mm self­-propelled mortar. Both weapons were first shown in a parade in Moscow on November 7, 1957. According to Khrushchev, the gun was too big and heavy and performed badly.

As scientists steadily pushed the technological envelope with new weaponry, the atomic cannon soon lost its utility. Improved guns and ammunition were developed, but engineers were focused on developing nuclear­-armed rockets and guided missiles, beginning in 1957 with the short­range unguided ballistic missile known as the FROG (free-­rocket overground). By the early 1960s, American atomic shells had become small enough to be compatible with standard army artillery, such as the M1 and M2 8­inch (203mm) howitzers and the M43 self­-propelled howitzer, and the M1 and M2 155mm guns. The M­454 housing the W48 warhead was eventually produced for the M1 and M2 155mm guns and later the M109 self­-propelled vehicle with 155mm gun.

All this meant that the 280mm atomic cannon T131 had become obsolete and it was gradually phased out of service. The last was retired in 1963, barely a decade after the Nevada test shot. Nuclear-­capable artillery remain in service with the U.S. Army today, but the atomic ammunition was destroyed in accordance with the Intermediate­-Range Nuclear Forces Treaty, signed with the Soviet Union in 1987.

Of the 20 atomic cannons produced, eight are now on public display. The largest sits in a public park in Junction City, Kansas, and others can be found at the Yuma Proving Ground in Arizona and the Rock Island Arsenal in Illinois. The original Atomic Annie is at the Fort Sill Museum in Oklahoma.


C. G. Sweeting is the author of several books, including Hitler’s Personal Pilot: The Life and Times of Hans Bauer.

Originally published in the January 2014 issue of Military History Quarterly. To subscribe, click here.