The US Army only ever fired one nuclear artillery shell from its ‘Atomic Annie’ cannon, and this is what it looked like

Image of the May 25, 1953 test-firing of an M65 atomic cannon.
Image of the May 25, 1953 test-firing of an M65 atomic cannon.

  • The US Army fired its atomic cannon for the first and last time 68 years ago.
  • The cannon, initially named “Able Annie,” was later renamed “Atomic Annie.”
  • During the May 25, 1953 test, the cannon fired a nuclear shell that unleashed a 15-kiloton blast.
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The US Army successfully test-fired an atomic cannon exactly 68 years ago Tuesday. It was the first and only time the US military ever fired a nuclear weapon from a conventional cannon, according to the Army.

During the Cold War, the US military developed many different ways to unleash nuclear destruction on an enemy, including a towed artillery piece built in the early 1950s that could fire a nuclear round packed with as much explosive power as the atomic bomb that devastated Hiroshima less than a decade earlier.

The Army’s M65 280 mm Motorized Heavy Gun, the largest mobile artillery piece the US ever built, was based on Nazi Germany’s Krupp K5 heavy railway gun, a devastating indirect-fire weapon Allied service members fighting in Italy during World War II named “Anzio Annie.”

The M65 "Atomic Annie," a 280mm nuclear-capable cannon, sits on a concrete slab at Fort Lee
The M65 “Atomic Annie,” a 280mm nuclear-capable cannon, sits on a concrete slab at Fort Lee, where it currently resides.

Weighing roughly 85 tons, the M65 cannon required two transporter trucks to move. In 1953, the US military moved two of these cannons by rail from Fort Sill, Oklahoma to a test site in Nevada, where crews used one to fire a nuclear artillery round in the first and last test of the cannon’s capabilities.

On May 25, 1953, just a few months after an M65 cannon made a very public debut in the inaugural parade for President Dwight D. Eisenhower, Army crews used a cannon named “Able Annie,” one of only 20 M65 guns ever made, to fire a nuclear artillery shell.

The atomic cannon test, codenamed Grable, was the tenth in the Operation Upshot-Knothole nuclear weapons test series but the only one involving nuclear artillery. The cannon, which cost $800,000, performed as expected.

About 19 seconds after the shell was fired at 8:31 am, it exploded just under 8 miles away at a low-burst height of about 520 feet.

“The shell that could wipe out an enemy division exploded on target with a roaring violence equal to 15,000 tons of TNT,” a historical marker at Fort Sill reads.

With that shot, “Able Annie” became “Atomic Annie.” Though the name applies to one gun, it has been used to refer to M65 cannons in general.

The other M65 cannon that was present for the testing in Nevada but never fired was a backup cannon named “Sad Sack,” a weapon that has had a rather uneventful history compared to Atomic Annie.

After the testing wrapped up, Sad Sack was supposed to be sent to an operational unit for overseas deployment while Atomic Annie was to return to Fort Sill, but during the transport process, the two cannons were accidentally switched.

This error was not discovered for 10 years. Soldiers preparing the big cannon for an event marking the tenth anniversary of the Grable test at Fort Sill realized that the serial numbers did not match that of Atomic Annie, the whereabouts of which were unknown to most at the time.

"Atomic Annie" at Fort Lee
“Atomic Annie” at Fort Lee

When the Army tried to find “Atomic Annie,” which was briefly renamed “AWOL Annie” during the search, it was a bit of challenge because the atomic artillery pieces had been deployed across Europe and Asia, and their specific locations were classified to the point that only a limited number of people actually knew exactly where they were.

The legendary atomic cannon was eventually found in Germany and retrieved. It returned to Fort Sill in 1964, and Sad Sack was given to the Smithsonian, according to the Army.

Due to the rapid pace of nuclear-weapons development during the Cold War, the M65 cannons like “Atomic Annie” were obsolete within a decade of their initial fielding. The M65, which was fielded to deliver a devastating nuclear strike behind enemy lines, was withdrawn from service in 1963, just 10 years after the first and only shot.

In 2017, the Atomic Annie cannon was moved to Fort Lee in Virginia, where it joined another “Annie,” one of the captured German K5 railway guns. The massive M65 cannon is part of an educational and historical display at the installation’s new Ordnance Training Support Facility.

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How a daring raid by Norwegian commandos kept the Nazis from building a nuclear bomb

Norway Nazi Germany World War II WWII
  • In late February 1943, nine commandos set out of daring raid against the Germans in the Norwegian wilderness.
  • Their mission, to destroy a plant producing heavy water, would fulfill one of the Allies’ most important goals: Prevent the Nazis from building an atomic bomb.
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At 8:00 p.m. on February 27, 1943, nine Norwegian commandos trained by the British Special Operations Executive (SOE) left their hideout in the Norwegian wilderness and skied several miles to Norsk Hydro’s Vemork hydroelectric power plant.

All the men knew about their mission was the objective: Destroy Vemork’s “heavy water” production capabilities.

Each man carried a cyanide capsule to take if they were captured and wore a British Army uniform so if they were killed and their bodies found, the Germans might spare the local civilians from reprisal killings.

Their mission would be one of the most successful in special-operations history, and it contributed to one of the Allies’ most important goals in World War II: Preventing Nazi Germany from developing nuclear weapons.

The race for an atomic bomb

Nazi Germany nuclear bomb weapons lab
The German experimental nuclear pile at Haigerloch, southwest of Stuttgart, being dismantled in April 1945.

Within months of the discovery of nuclear fission on December 17, 1938, the military potential of nuclear power became clear, and the race for an atomic weapon was on.

In April 1939, Germany started its nuclear-bomb effort, known informally as the Uranverein, or “uranium club.” It included some of the best scientists in the field, including the men who discovered nuclear fission and Nobel Prize-winner Werner Heisenberg.

During their research for a nuclear reactor, the scientists discovered that deuterium oxide, known commonly as “heavy water” because it has a heavier molecular weight than regular water, performed well as a moderator, enabling control over the fission process.

There was only one place in the world capable of producing heavy water on an industrial scale: Norsk Hydro’s Vemork hydroelectric power plant in southern Norway. The plant’s main purpose was to produce ammonia for nitrogen fertilizer; heavy water was actually a byproduct.

In January 1940, German officials asked to buy all of Norsk Hydro’s heavy water stock and if it was possible to increase the plant’s monthly output 10-fold to meet German demand.

This caught the attention of the French, who were experimenting with nuclear physics themselves and pursuing heavy water. Worried about German intentions, agents from the Deuxième Bureau, France’s military-intelligence agency, secured all of Norsk Hydro’s heavy water for France on March 9.

It was only a temporary setback for the Nazis. Exactly a month later, Germany invaded Norway and occupied it by early June. Vemork, now under German control, was forced to increase heavy-water production.

Operations Grouse and Freshman

Vemork Tinn Norway nuclear lab
The Vemork hydroelectric power plant, February 24, 2011.

The Allies, unaware of the German nuclear program’s progress, were increasingly worried that Germany may be ahead in the race. Vemork’s heavy-water production was known to be important to the program, and that alone was a good enough reason to take action against it.

Working with the Norwegian Resistance, the SOE created a plan for two teams to be dropped into Norway.

The first, codenamed Operation Grouse, was made up of four SOE-trained Norwegian commandos who would parachute into Norway, conduct reconnaissance, and secure a landing zone for a 34-man team of British commandos, codenamed Operation Freshman, who would land in two gliders and then assault the plant and destroy the 18 electrolysis cells that made heavy water.

On October 18, 1942, Grouse was launched. The team spent the next few weeks trekking to Freshman’s designated landing site, reaching it on November 9. On November 19, Operation Freshman was launched.

But Freshman was a colossal failure. Mechanical difficulties and bad weather caused one of the bombers and the glider it was towing to crash, killing the flight crew and a number of commandos. The second glider’s cable snapped when the bomber towing it aborted the mission, causing it to crash as well.

Survivors from both gliders were found by the Germans and executed as per Hitler’s Commando Order. Forty-one men were lost, security at Vemork was increased, and the Grouse team was stranded and had to fend for itself.

Operation Gunnerside

Norway Nazi Germany Norwegian Heavy Water Sabotage
A reconstruction of the Operation Gunnerside team planting explosives to destroy electrolysis chambers in the Vemork heavy-water plant.

Vemork was still a priority target for the Allies, and a new plan, with a stealthier approach, was developed.

A team of six Norwegian commandos would be dropped into Norway to link up with members of the Grouse team. They would infiltrate the plant, destroy the heavy-water production room with explosives, and escape into the night.

Codenamed Operation Gunnerside, the team parachuted into Norway on February 16, 1943, and linked up with the Grouse team on February 22. On the night of February 27, nine members from both teams set out for Vemork, with one member remaining behind to communicate with the British.

Upon arrival on the outskirts of the plant, they saw that the bridge, the only direct way into the complex, was heavily guarded.

The team had to descend a 328-foot cliff, cross a frozen river, then climb an almost 500-foot cliff before arriving at a fenced railway gate that led into the rear of the complex. They got there at 11:45 p.m. but had to wait for the guards to change shift, eventually cutting their way through the fence after midnight.

Once inside, the team split into two groups. Five commandos took covering positions outside the barracks, bridge, and main gate, while the other four entered the plant. Inside, they encountered only a Norwegian employee, who didn’t resist or raise the alarm.

Explosives were set in the target room, which was in the basement. The team evacuated and waited for the explosion. Because the room was so far underground and the walls were so thick, there was hardly any noise when the bombs went off, allowing the whole team to escape before the Germans found out what had happened.

Aftermath

Joachim Ronneberg Norway Gunnerside
Joachim Ronneberg, leader of Operation Gunnerside, at a ceremony in his honor in London, April 25, 2013. Ronneberg died in 2018.

The operation was a resounding success. The commandos destroyed the electrolysis cells and over 500 kg of heavy water. They managed to escape without firing a single shot or taking any casualties.

The Germans repaired the damage by May, but subsequent Allied air raids prevented full-scale production. Eventually, the Germans ceased all production of heavy water and tried to move the remaining supply to Germany.

In a last act of sabotage, a Norwegian team led by one of the Gunnerside commandos sank the ferry transporting the remaining heavy water on February 20, 1944, although at the cost of 14 Norwegian civilians.

The operations helped foil Germany’s nuclear ambitions, and the Nazis never built an atomic bomb or a nuclear reactor. Nazi Germany surrendered to the Allies in early May 1945, two months before the US’s bigger and better-resourced Manhattan Project tested the first nuclear weapon on July 16, 1945.

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