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16 February 2015

This Nuke Proved Size Doesn’t Matter

by PAUL HUARD

The Davy Crockett was a tiny, unnerving, atomic tank-killer

Early in the Cold War, NATO worried that thousands of Russian tanks might pour through the Fulda Gap—the lowland corridor between Frankfurt and the East German border—and overwhelm alliance forces.

The Warsaw Pact’s advantage in armor was huge. Some intelligence analysts predicted that a single NATO battalion—a 300 0r 400 troops and 40 or 50 fighting vehicles—could face as many as 120 advancing Soviet tanks within 30 minutes. And there would be even more follow-on forces behind the initial armored wave.

So many Soviet tanks could roll into West Germany that some NATO planners grimly joked—or half-joked—that their war strategy was to “fall back to the Pyrenees and go nuclear.”

From 1961 to 1967, one way U.S. forces could “go nuclear” in Europe was tiny … and unnerving for its own users. The Davy Crockett was a recoilless rifle that fired a 76-pound atomic projectile—the smallest, lightest nuke ever deployed by the United States.

It was a classic example of why in some cases size doesn’t matter. In an age before modern anti-tank missiles, the Davy Crockett was a battlefield equalizer designed to fry enemy tank crews with gamma rays and help stop a Soviet invasion cold.

In theory. In practice, it never would have worked.

Beginning with the administration of Pres. Dwight Eisenhower in the 1950s, the U.S. deployed many nuclear weapons to Western Europe, ranging from gravity bombs to intermediate-range ballistic missiles based in the U.K and West Germany.

But there was also a growing feeling among planners and some politicians on both sides of the Atlantic that if annihilating cities and military installations was the only nuclear option, then the Soviets gained a battlefield advantage.

In principle if not in reality, NATO could detonate tactical nuclear weapons without wiping out huge swaths of Europe.
Advocates of small nukes maintained that tactical atomic weapons would boost deterrence—the Soviets would be less inclined to launch an invasion if they knew NATO could nuke their tanks.

The designers of the Davy Crockett used an existing fission device as the basis of its W-54 warhead. The W-54 was tiny compared to other nuclear weapons of the time, but that didn’t make it less deadly, according to Carey Sublette, a nuclear weapons historian and creator of The Nuclear Weapon Archive.

“By their nature, all very small nuclear weapons have a larger ‘kill radius’ from the radiation emitted instantly by the nuclear explosion than from blast or thermal radiation flash,” Sublette told War Is Boring.

“Armor provides essentially complete protection against blast and thermal radiation,” Sublette continued. “It attenuates but does not stop ionizing radiation, so the explosion would irradiate and eventually kill the crew inside the tank.”

At top—U.S. Army troops with a Davy Crockett. Army photo. Above—U.S. Atomic Energy Commission officials examine the Davy Crockett’s atomic round containing the W-54 warhead. U.S. Department of Energy photo

Launched by a 120-millimeter or 155-millimeter recoilless rifle, the Davy Crockett needed a three-man crew and a Jeep or armored personnel carrier to move it around. With the 155-millimeter launcher, the Davy Crockett had a range of 2.5 miles.

The warhead’s yield was miniscule compared to the strategic nukes of the time—the equivalent of 20 tons of TNT, enough to pulverize a large building. But the radiation it released would instantly kill anyone within 500 feet of ground zero and sicken and kill humans up to a mile away under some conditions.

Nuclear weapons manufacturers produced more than 2,100 warheads for the Davy Crockett system. Starting in 1962, the U.S. Army in Europe deployed hundreds of Davy Crocketts, particularly with the 3rd Armored Division, the guardians of the Fulda Gap.

There was even serious discussion of arming West German units with the Davy Crockett.

But the weapon had numerous drawbacks. The atomic round was not cheap—it cost almost as much to build as a strategic nuclear weapon did, because of the expensive fissile material in the warhead.

It also posed a serious danger to its crew. The lethal radiation released by the weapon exceeded its minimum range, meaning the soldiers who launched the Davy Crockett could be killed by the same gamma rays intended for Soviet tank crews.

But the greatest unintended danger was inherent in the very design of the weapon. The problem with a man-portable atomic round is the security risk—it would be easy to steal.

“Each warhead, though only yielding 10 tons of explosive energy, could be reworked with a more powerful explosive charge into a Hiroshima-sized bomb if someone with suitable skills were to seize one,” Sublette noted.
The development of accurate and reliable man-portable and armor-mounted anti-tank missiles sounded the death-knell of the Davy Crockett on the European frontier between NATO and the Warsaw Pact.

Sublette said it’s possible that the fissile material in the Davy Crockett round wound up in the multiple independently target re-entry vehicle warheads the U.S. placed on its ICBMs in the late 1960s.

Yet, the Davy Crockett remained in the U.S. nuclear arsenal until 1971.
“U.S. Army Presents MF20 9811, Ivy Flats Film Report.” This declassified film from 1962 shows the detonation of a Davy Crockett nuclear round, the last U.S. atmospheric test of a nuclear weapon.

The tiny Davy Crockett atomic round also occupies another place in the history of the Nuclear Age. It has the distinction of being the last nuclear warhead the U.S. tested above ground at the Nevada Test Site before the implementation of the Partial Test Ban Treaty and its prohibition on atmospheric nuclear testing.

On July 17, 1962, Operation Ivy Flats carried out simulated maneuvers on an atomic battlefield. Several thousand Department of Defense personnel participated in the exercise, which included the live firing of a Davy Crockett round from a 155-millimeter launcher at a target 1.7 miles away.

In the audience were dignitaries including then-attorney general Robert “Bobby” Kennedy and Gen. Maxwell Taylor, future chairman of the Joint Chiefs of Staff and Pres. John F. Kennedy’s most trusted military adviser.

Dubbed the Little Feller II shot, the round detonated on-target less than 40 feet above the ground and had a yield equivalent to 18 tons of TNT.

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