How An Ammunition Problem Almost Destroyed Pearl Harbor A Second Time

Sebastien Roblin

Key point: The accident was deemed was so shocking the Navy instituted a press blackout.

Flames roiled into sky from dozens of burning ships, creating a wall of smoke that crept out into the Pacific Ocean. The thunder of multiple explosions succession shook the Navy Headquarters on Pearl Harbor.

Had Japan somehow pulled off a second, stunning raid on Pearl Harbor in 1944?

In truth the ships and men burning were victims of a horrifying accident born of inadequate safety measures—an incident the Navy kept under wraps for years.

How It Occurred:

In May 1944, a gigantic amphibious landing force began assembling at Pearl Harbor to carry U.S. Marines to capture the strategic Mariana islands from Japan, 3,700 miles away.

By May 21st, at least 29 Landing Ship, Tanks (LSTs) were strung beam-to-beam along six piers on West Loch—the western side branch of pincer-shaped Pearl Harbor.  These long boxy vessels displaced over 4,000 tons and 120 meters long.  The flat keels of the ocean-spanning ships allowed them to disgorge up to a company of tanks or infantry from their bow ramps directly onto a beach.

While roughly half the crew were on shore leave, the remainder rested onboard as the vessels were stuffed full of vehicles, ammunition and fuel. Dozens of barrels of high-octane gasoline were lashed to their decks to supply the vehicles once they were unloaded ashore. 

At 3 PM Army stevedores began unloading 4.2” mortar shells from a smaller Landing Craft Tank (LCT) onto the elevator of LST-353

So-called “chemical mortars” were used to deploy smoke rounds and burning white phosphorous shells to mark or obscure targets—as well as 24-pound high explosive rounds carrying eight pounds of TNT filler. But the heavy mortars proved too inaccurate fired firing from the LCTs, leading to their transfer back to LSTs. 

The personnel conscripted for the heavy lifting came from the 29th Chemical Decontamination Unit, a largely African-American unit which untrained in ammunition handling.

No one knows exactly what caused a fireball to erupt on LST-353 at 3:08 PM, because no nearby witnesses survived.

Perhaps one of the stevedores dropped a 4.2” shell. Some suggest sparks from a carelessly tossed cigarette, or from sailors doing spot welding, ignited the fuel vapor wafting from the roughly 80 barrels of gasoline tied next to the elevator.

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