by STEVE WEINTZ

In the spring of 1952, the U.S. government tested tactical nuclear weapons at the Nevada Proving Ground as part of Operation Tumbler-Snapper. It was the third nuke test series in 18 months at the Nevada site in an era of breakneck atomic development.

At 4:00 in the morning on May 13, one of the Tumbler-Snapper bombs — code name “Fox” — was scheduled to go off. But the moment passed … and no atomic fireball curled into the sky.

Shot Fox had misfired. Locked in its cab atop a 300-foot tower rising over the Yucca Flat, the malfunctioning 15-kiloton device posed a serious danger to living things for many miles in all directions.

Someone had to disarm the thing. What followed was one of the riskiest and most delicate jobs — well, ever.

Shot Fox began well enough. The night before H-hour at Yucca Flat’s Site Four, Dr. John C. Clark of the Atomic Energy Commission wired shut the shot cab’s door and watched as engineers took down the tower’s elevator. He joined other top scientists at the control point several miles away.

Some 500 U.S. military observers joined 950 troops from the Army’s 701st Armored Infantry Battalion — part of the 1st Armored Division — to experience the nuclear test from a point just a few miles from ground zero.

Psychologists from George Washington University and Johns Hopkins prepared to evaluate the observers’ reactions to atomic destruction. The 701st soldiers were guinea pigs for evaluating the bomb’s flash, burn and shock-wave effects under field conditions.

The countdown sequence ran smoothly up to H-hour, then … nothing.