"Atomic Annie," U.S. M65 Atomic Cannon, Fired for Only Time

 
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"Atomic Annie," U.S. M65 Atomic Cannon, Fired for Only Time

M65 atomic cannon prototype (240mm) on display at the
Virginia War Museum, Newport News, VA
(Unless otherwise indicated, all illustrations are courtesy of Wikipedia)

Today in Military History: May 25, 1953

During that time period between the Second World War and the fall of the Soviet Union, the American military was constantly searching for the latest "Wonder-Weapon." In the early 1950s, a tactical nuclear delivery system was developed, tested, and soon fell into obsolescence. This is the story of the M65 Atomic Cannon, also known as "Atomic Annie."

Background

The Japanese had made a strong impression on their European counterparts when they employed 280mm howitzers against Port-Arthur during the Russo-Japanese War of 1904-5. The French and the Russians collaborated afterwards to develop a similar weapon.

The Germans had developed a similar weapon during the First World War – known as the "Paris Gun" – which bombarded the city of Paris for about 6 months in 1918. [For more information on this weapon, please see my BurnPit piece from March of 2011: Colossal German Cannon Shells Paris From 75 Miles Away.]

The M65 was based on the design of the 280mm (about 11 inch) German K5 Railroad Gun. Its design, and name, both derive from the German K5(E) railroad gun dubbed "Anzio Annie" by American GIs who were its targets in Italy in the Second World War.

After the conclusion of the Second World War, American military strategists began to ponder the possibility of a tactical nuclear device, a smaller version of the weapons used against Hiroshima and Nagasaki, Japan in August of 1945. With the advent of the Cold War, the U.S. felt it needed every ace-in-the-hole it could use against the Soviet Union.

In 1949, Picatinny Arsenal in New Jersey was given the mission to develop an artillery shell able to carry a nuclear payload. Basically, this meant scaling a 240mm shell – the Army largest field artillery shell in the Second World War – up to 280mm. The project's entire design team was Robert Schwartz, who completed his preliminary sketches during a period of 15 days spent alone in a locked room at the Pentagon. He sharpened the details in another locked room at the Picatinny Arsenal. The Chief of Staff of the Army at the time, General J. Lawton Collins, thought enough of Schwartz's effort to cite him in his memoirs over a quarter of a century later.

The next problem was to sell the product to the Pentagon. This would not have happened if Samuel Feltman, chief of the Ballistics Section of the Ordnance Department's Research and Development Division, had not pushed the project to approval. Then, Schwartz had to rush to procure equipment and assemble a staff to carry out the three-year development effort.

M65 Atomic Cannon, aka "Atomic Annie"

Officially labeled the M65 and nicknamed "Atomic Annie," the gun wound up being the largest road-mobile artillery the U.S. ever put into production at some 84 feet long, with a total weight of 83 tons. The 38.5-foot long barrel had a 280mm bore, some 11 inches across. [For an idea of just how big this is, you can slip a regulation bowling ball into the muzzle and almost half an inch to spare all the way around.]

W9 warhead being prepared for firing; Image courtesy of http://www.guns.com/2013/08/15/atomic-annie-the-us-armys-nuclear-cannon
W9 warhead being prepared for firing; Image courtesy of
http://www.guns.com/2013/08/15/atomic-annie-the-us-armys-nuclear-cannon/

The round that gave Atomic Annie her nuclear nickname, the W9 warhead, was 11 inches wide, 55 inches long and weighed 803 pounds. It used 110 pounds of enriched weapons-grade uranium, arranged in an advanced "ring and bullet" system that collided when fired and set the device on a 15-kiloton chain reaction by the time it hit the target. This was slightly lesser yield than the explosion of the Hiroshima bomb, just in a much smaller package. [The "Fat Man" bomb that was delivered over Hiroshima weighed 10,300 pounds, was just over 10 feet long and had a diameter of 5 feet. It delivered an estimated 21 kilotons of explosive power]

The M65 was transported between detachable front and rear transport tractors (known as "prime movers"). With a 375 horsepower diesel prime mover tractor pushing the rear of the carriage, and another pulling it from the front, "Annie" could be moved at speeds of up to 30 mph. A well-drilled five man crew could stop the M65 at an unprepared site, set it up, fire a nuclear-tipped shell at a target up to 18 miles away, and be rolling again all within 30 minutes.

Grable Test-Fire, May 25, 1953

On May 25, 1953, at 8:30 am a single test shot was fired at the Nevada Proving Grounds at Frenchman's Flat, Nevada at 8:30am, local time. The Atomic Cannon test was history's first atomic artillery shell fired from the Army's new 280-mm artillery gun. Operation Upshot-Knothole consisted of 11 atmospheric detonations, took place at the Nevada Test Site between March 17 and June 4, 1953. There were three airdrops, seven tower shots and one warhead fired from an atomic cannon. The M65 test-firing was dubbed Grable, and was the next-to-the-last of the 11 tests. About 20,000 military personnel participated in Upshot-Knothole as part of the Desert Rock V exercise. The W9 warhead travelled just under 7 miles before detonating.

Grable test-shot of M65 atomic cannon (in right foreground), May 25, 1953
Grable test-shot of M65 atomic cannon (in right foreground), May 25, 1953

Twenty of the M65’s were manufactured. The first atomic cannon went into service in 1952, and was deactivated in 1963. Throughout the 1950s, the Army deployed nuclear cannons to Europe even though they were obsolete as soon as they arrived. Guarded by infantry platoons, these guns were hauled around the forests on trucks to keep the Soviets from guessing their location. Weighing 83 tons, the cannon could not be airlifted and took two tractors to move its road-bound bulk. It was a glamorous weapon to be sure, but it siphoned off precious funding that the Army desperately needed for modernization.

Aftermath

Pulled from the front lines, some of these guns were torched and scrapped overseas rather than be sent back home. The 79 remaining W9 shells were cut down and made into T4 ADM bombs, one of the earliest "backpack nukes," which kept them in quiet service for a while longer. The US military got out of the nuclear artillery shell business in 1991, at the end of the Cold War. The final 155mm and 203mm shells were dismantled in 2004.

Footnote #1: President Dwight Eisenhower took the oath of office on Tuesday, January 20, 1953. It was the most elaborate inaugural pageant ever held. About 22,000 servicemembers and 5000 civilians were in the parade, which included 50 state and organization floats costing $100,000. There were also 65 musical units, 350 horses, 3 elephants, an Alaskan dog team, and the prototype M65 280-millimeter atomic cannon.

Footnote #2: The May 1953 test-firing was attended by – among others – the Chairman of the Joint Chiefs of Staff and the Secretary of Defense. A number of members of Congress were also present.

Footnote #3: Eight of the original 280mm cannon are still in existence. The "Atomic Annie" which fired the first atomic artillery warhead is on display at the U.S. Army Artillery Museum at Fort Sill, Oklahoma. It was restored in 2010 to its 1953 condition, including its two "prime movers."

Footnote #4: During the height of the Cold War, several model manufacturers used the M65 atomic cannon as one of their models for children to play war (and to demonstrate their abilities to assemble a plethora of plastic parts to resemble the picture on the box).

Box cover art, 280mm atomic cannon, this model manufactured by Renwal; Revell Company acquired the Renwal molds and re-issued this model in 2013, Image courtesy of http://www.theatomiccannon.com/model_kits
Box cover art, 280mm atomic cannon, this model manufactured by Renwal
Revell Company acquired the Renwal molds and re-issued this model in 2013,
Image courtesy of http://www.theatomiccannon.com/model_kits

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Comments

A complete failure from a practical sense.
If the atomic shell was actuated by the initial propellant charge explosión, then the range was fixed at one and only one distance. The enormous g force from the firing means that it was no way the the atomic bomb critical mass halves could be kept apart, so they "designed" it that way, so that every shell underwent initiation at the firing of the cannon, then this weapon could only adjust the distance to target by varying the gunpowder loading, but since the initiation event is started by the firing, the flight time before the atomic explosion is fixed, and thus the range is fixed. A very non versatile weapon at all. Missiles on the contrary, have much lower accelerations, and thus are capable of sending their payloads in a much more controlled manner. Surprising how stoopid was the quest for weapons during the cold war!

Missiles took way more sophistication as well as resources....My grandfather was in command of one of these atomic cannons and he had no complaints about what you speak of. For the time that the cannon was in use it was not supposed to be a practical option for attack, it was simply a deterrent for Soviet troops from coming across the boarder into West Germany because they would have been nuked before they could get across the border.

AMCLAUSSEN's comment may have been valid if he was correct in the functions of the atomic projectile. I commanded a 280 gun platoon in the 1950's, and have disassembled and assembled the projectile (trainer). The function of the shell was NOT initiated by the action of firing the gun. There was a timing mechanisn whose delay was dictated by the time-of-flight of the projectile, and a redundant detent system to preclude the "getting together" of the fissionable components before the intended moment. At detonation, the critical parts were literally shot into contact, achieving criticality over the target. The gun itself was sufficiently accurate to drop an HE round on a tennis court at 15 miles. This was largely due to finely computed firing table which took into account every possible variable of metro, earth movement, powder temperature, etc. It took about 30 minutes for the average specially trained fire direction center to compute firing data.

I spent two and a half years Darmstadt germany keeping our battery gun running.Ludwig kaserne B battery 2nd battalion 38 field artillery.

Amclausen overlooks the fact that designing an atomic shell that could tolerate the propellant and g forces of a cannon shot was considered scientifically impossible. Also, the effort at producing a ground based launch system made a nuclear strike possible 24/7 for the first time since airdrops were limited to daytime and good weather. The Atomic Annie was the first stop on the road to the Davey Crockett nuclear weapon also developed at Picatinny Arsenal in Nj that let a nuclear shell be launched by an oversized bazooka from the back of a jeep or by a tripod on the ground by a 2 men team.

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News from the World of Military and Veterans Issues. Iraq and A-Stan in parenthesis reflects that the author is currently deployed to that theater.