Introduction 

On May 25, 1953, during the Operation Upshot-Knothole test series at the Nevada Test 

Site, a milestone occurred in ordnance 

development. A 280-mm cannon, nicknamed 

Atomic Annie, fired the first and last nuclear 

projectile as part of the Grable test. The MK-9 

artillery shell was propelled a distance of seven 

miles. It exploded in the air and had a yield of 

15 kilotons (15,000 tons of TNT). 

Deployment 

Two 280-mm cannons were shipped by rail from 

Fort Sill, Oklahoma, to Las Vegas, Nevada, 

along with a twenty-eight man artillery crew. 

The cannons were transported to the Nevada Test 

Site, about 65-miles northwest of Las Vegas, 

where crews spent a month conducting firing 

A 280 mm cannon nicknamed Atomic Annie fires a 15 kiloton nuclear practice before the nuclear projectile was 

projectile, which detonated 524 feet above Frenchman Flat . The actually fired.

familiar mushroom cloud occurred seven miles to the north of the 

cannon. 

According to Charles Ball, an Army Private at 

One of the two 280 mm cannons fires a practice round at the Nevada 

Test Site 

the time, "the two cannons were emplaced side 

by side just east of the Mercury Highway, about 

seven miles to the south of Frenchman Flat. 

Prior to our arrival, engineers had bulldozed a 

packed dirt road to take the weight of the two 

cannons. That was one of the drawbacks of the 

280-mm cannon. Because it weighed 88 tons, it 

could only be driven on normal roads, or 

prepared surfaces." 

Test Grable 

Grable was the tenth test of Operation 

Upshot-Knothole. The nuclear projectile was 

detonated at 8:30 a.m. (PDT) on May 25, 1953. 

The projectile detonated 524 feet above 

Frenchman Flat. It is the only nuclear device 

ever fired from a cannon. After the test, the 

cannons and gun crews returned to Fort Sill. 
Conclusion 

Twenty cannons were eventually made, 

but over the years, the value of the 

280-mm atomic cannon and the artillery 

shells it fired diminished appreciably. 

The military value of the enormously 

heavy cannon was limited because the 

cannon was confined to only the best 

paved roads. Also, the quick 

development of atomic capability in 

several smaller calibers (8 inch and 

155mm) made the weapon obsolete. 

Today, four cannons still exist. In 

addition to the original Atomic Annie at 

Fort Sill, three others can be seen at the 

National Atomic Museum, Albuquerque, 

New Mexico; Fort Riley, Kansas, and 

Aberdeen Proving Ground, Maryland. 

One of the 280 mm cannon's is shown completely assembled at Nellis Air 

Force Base on May 18, 1953, where it had just arrived by rail from Fort Sill, 

Oklahoma. Although it weighed 88 tons, its carriage was an ingenious 

foundation carried between two wheeled transporters, which were capable of 

speeds up to 40 miles per hour. 

Why a Cannon? 

During World War II, the U.S. Army voiced a need for a mobile, long-range heavy artillery weapon capable of 

attacking enemy communication centers, field fortifications and as counter-battery fire on enemy long-range artillery. 

After the war, it became apparent that a cannon meeting such capabilities could have its firepower greatly enhanced 

with the simultaneous development and deployment of an atomic warhead artillery shell. The difficulty of the task 

was reducing an atomic device to fit a cannon. 

In 1952, the largest piece of mobile artillery ever constructed in the United States was ready. The $800,000 280-mm 

Atomic Cannon weighed 88 tons and was moved on a carriage fitted between two transporters capable of being 

driven at 40 miles per hour. The cannon could be set-up and ready to fire in 10 to 15 minutes. 

For more information, contact: 

U.S. Department of Energy 

National Nuclear Security Administration 

Nevada Site Office 

Office of Public Affairs 

P.O. Box 98518 

Las Vegas, NV 89193-8518 

phone: 702-295-3521 

fax: 702-295-0154 

email: nevada@nv.doe.gov 

http://www.nv.doe.gov 

DOE/NV - - 776 

June 2004