The Mars Bluff Incident — The Story of the Only Nuke Ever Dropped on American Soil

An MK-6 Nuclear Bomb like the one dropped on Mars Bluff.

An MK-6 Nuclear Bomb like the one dropped on Mars Bluff.

The specter of nuclear death hung like a pall over the middle part of the last century. With the Soviet Union detonating bigger and bigger bombs, and the US deploying nuclear weapons of various sizes to the European border with the Communist superpower, the threat of nuclear annihilation was a very real one.

Fortunately, although there were several incidents like the infamous Cuban Missile Crisis where the world came very close to an all out nuclear exchange between the US and the USSR, the US has never had a nuclear bomb dropped on it in anger, outside of a test site. I say “in anger” because on March 11, 1958, a nuclear bomb was dropped on American soil quite by accident.


An unfortunate accident

What has become known as the Mars Bluff incident began with 4 B-47E bombers taking off from Hunters Air Force Base near Savannah, Georgia. The four planes were on route to England to take part in a mock bomb run as part of a mission called Operation Snowflurry. The bombers would fly to England and pretend to deploy bombs, while electronic receivers on the ground picked up data that could be used to refine the accuracy of the planes’ targeting systems.

While the mission was a mock run, each plane carried a very real MK-6 nuclear bomb on board, just in case World War III broke out while they were en route and they had to take part in a nuclear strike against the Soviet Union. The core of the nuclear device was kept separate from the casing, in a storage case known as a “bird cage.”

Everything was going according to plan as the group of planes made their way toward the Atlantic Ocean. However, they were passing over the area outside Florence, South Carolina when the co-pilot of the third plane pulled the lever meant to engage a locking pin on the MK-6’s harness. A light flipped on indicating that the pin had not engaged. The co-pilot dispatched navigator Bruce Kulka back to inspect the problem. Bruce was a short man, and the MK-6 was a big bomb (10 feet long and 7000 pounds big). He climbed up to inspect the locking harness, but while doing so he pulled the emergency bomb release lever by mistake. The bomb dropped down and slammed into the bomb bay doors. The combined weight of Bruce and the bomb forced open the bomb bay. Bruce barely managed to save himself, but he could only look on helplessly as the MK-6 plummeted to Earth.


A big (conventional) explosion

Walter Gregg and his family were enjoying a bright, pleasant day on their family farm situated on Mars Bluff about six and a half miles from Florence, South Carolina.. When Gregg heard a B-47Es flying overhead, he thought nothing of it. But the next moment their peaceful afternoon became a maelstrom of chaos. The bomb hit behind the home in what had been the family garden, and the high explosives that would have kick started the nuclear reaction had the core been in place detonated, excavating a 50 foot by 70 foot crater. The explosion flattened nearby pine trees and shifted the Gregg family home off its foundation, destroying nearly everything inside. The blast totalled both of the family’s cars. The cloud of dust and debris was visitable from the courthouse roof, about eight miles away. Luckily, the family only suffered relatively minor injuries from flying shrapnel and other debris.

Within a few hours, the Air Force descended on the site and established a two mile perimeter. They asked locals to turn in any pieces of the bomb that they happened to come across. Air Force officials stated unequivocally that there was no threat of radiation from the detonation, because the bomb had not been armed with its nuclear payload. This was before revelations about nefarious government activities of various sorts, so people then were more trusting of those in authority than they are today. So, locals accepted the explanation and did as they were asked.

While the government promised to repair the damage and pay the family for its trauma, it never did fill in the crater and only offered a paltry sum of $44,000 in compensation. The family demanded more, and for good reason. Their lives were turned upside down in the wake of the accident. The Gregg children suffered nightmares and bouts of bedwetting after the explosion. Walter Gregg himself suffered hearing loss, while his wife had chronic headaches. Their cleaning woman had unusually long lived and painful menses after the blast, while Walter Jr. developed crossed eyes. In addition to all that, the family’s home was still destroyed and there was a swimming pool sized crater in their back yard. The family left the farm and moved into Florence. After a series of offers, counter offers, and law suits, the family finally settled out of court for $56,000. The crater is still visible today, although it is overgrown and starting to erode away in the fifty-six years since it was created one fateful March day, when American accidentally nuked itself.



Dittrich, Luke, “A Perfectly Understandable Mistake.” May 1, 2005. Esquire. April 6, 2014. <>

Klepper, David. “Man Recalls Day a Nuclear Bomb Fell on His Yard.” The Sun News. November 24, 2003. Retrieved from:

“Mars Bluff Bomb.” The Florence County Museum. April 6, 2014. <>





One thought on “The Mars Bluff Incident — The Story of the Only Nuke Ever Dropped on American Soil

  1. Art Brown, Councilman

    I was either Ass’t Crew Chief or third man on the Ground Crew that launched the aircraft. While securing the parking area two staff cars arrived and took the ground crew to the command center where we were debriefed on everything we did. They were most interested if we had entered the bomb bay or even looked inside. We had not and were never allowed around the bomb bay when a device was loaded. Were later taken back to our area and told never to speak about the incident. I never did until a book “Americas Nuclear Accidents” came out and I read about it.

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