Japan laughed at America’s “broken” torpedoes, then, one strike erased their largest cruiser in just 30 seconds

The black waters of the Surigao Strait were a graveyard in the making. At 03:35 on October 25, 1944, Lieutenant Junior Grade Isidor Kovar stood on the bridge of PT-137, straining his eyes against the ink-black horizon. He was 24 years old, seven months into his command, and tonight, he was effectively blind.

Three hours earlier, PT-137’s auxiliary generator had shrieked and died, taking the boat’s radar and radio with it. In the middle of the largest naval battle in history—the Battle of Leyte Gulf—Kovar was commanding an 80-foot wooden Elco boat with nothing but moonlight and the occasional flash of distant gunfire to guide him.

Below him, over 40,000 tons of Imperial Japanese Navy steel was racing north. Admiral Shima’s Southern Force, led by heavy cruisers and destroyers, was charging toward an American beachhead. If they broke through, 20,000 American troops would be pulverized by 14-inch shells at dawn.

THE “DUD” IN THE TUBE

Kovar spotted a silhouette: a Japanese destroyer slicing through the water at 20 knots. It was a straggler, separated from the main force. Kovar used hand signals to order his crew to battle stations. No whispers, no lights.

He had three torpedoes left. He had already fired one earlier that night, only to watch it “porpoise”—leaping out of the water like a dolphin before diving straight to the seabed. That was the reputation of the Mark 8 Torpedo.

Designed in 1938, the Mark 8 was powered by grain alcohol and compressed air. It was notoriously temperamental. PT crews called them “swimming slot machines” because hitting a target was less about skill and more about manufacturing luck. They had a documented failure rate of 30%. If the water was too warm, they ran deep; if too cold, they ran shallow.

Kovar closed the distance to 900 yards—deadly close. He centered the destroyer in his sights and pressed the trigger. With a pneumatic hiss, the Mark 8 slid into the water. Its wet heater engine ignited, leaving a glowing green phosphorescent wake.

THE SHOT THAT “MISSED”

Kovar counted the seconds. One… ten… twenty… The green wake tracked perfectly toward the destroyer’s midsection. Kovar braced for the explosion. But as the torpedo reached the ship, nothing happened. The destroyer surged past the torpedo’s track without slowing down. No fire. No metal rending.

Kovar slumped. Another Mark 8 failure. Another $1,500 of American ordnance vanished into the deep. “We missed,” someone muttered.

Then, the night erupted.

Eight hundred yards behind the destroyer, a colossal geyser of yellow-orange flame shot 200 feet into the air. The concussion wave hit PT-137 seconds later, rattling its mahogany hull so violently that a gunner was knocked off his feet.

Kovar stared into the darkness. What did we just hit?

THE PHYSICS OF LUCK

What Kovar didn’t know—and wouldn’t know for months—was that his Mark 8 torpedo had a manufacturing defect. A hydrostatic valve spring had been compressed just 0.005 inches too much at the factory in Newport, Rhode Island.

This tiny error caused the torpedo to run at 15 feet deep instead of the intended 10 feet.

• The Destroyer: A Japanese Fubuki-class destroyer only draws about 7 feet of water. Kovar’s “failed” torpedo had passed harmlessly beneath its keel.

• The Ghost Target: 900 yards behind that destroyer was the Abukuma, a 5,500-ton Nagara-class light cruiser. As a much larger ship, the Abukuma drew 16 feet of water.

Kovar’s torpedo, running deep and true, struck the Abukuma exactly 11 feet below the waterline, slamming directly into the Number One Boiler Room.

THE DEATH OF THE ABUKUMA

The explosion was catastrophic. Thirty-seven Japanese sailors died instantly as sea water snuffed out the boilers. The Abukuma, the flagship of Destroyer Squadron 1 and a veteran of the Pearl Harbor attack, groaned as its speed dropped from 36 knots to a staggering 10 knots.

Admiral Shima’s formation fell into chaos. Because the Abukuma was the command ship meant to relay orders, its sudden crippling led to a disastrous collision between two other Japanese cruisers, the Nachi and the Mogami. The Japanese retreat turned into a panicked rout.

Captain Hanata Takuo of the Abukuma fought to save his ship. For 27 hours, his engineers rerouted steam and welded plates, managing to limp the cruiser to Dapitan Harbor for emergency repairs. But they were out of time.

On October 26, the American 13th Air Force spotted the crippled giant. Forty-four B-24 Liberator heavy bombers were dispatched. Without air cover or the ability to maneuver, the Abukuma was a sitting duck.

At 12:07, the bombs began to fall. Three 500-pounders struck home. One penetrated the deck and detonated in the forward magazine, where the cruiser’s “Long Lance” torpedoes were stored. The secondary explosion tore the bow completely off.

At 12:42, the Abukuma—the largest warship ever credited to an American PT boat—slipped beneath the waves.

THE FORGOTTEN HERO

Lieutenant Isidor Kovar returned to base on October 26. In his after-action report, he was honest to a fault. He wrote that he had fired at a destroyer and missed. He mentioned the explosion in the distance but couldn’t confirm what it was.

It took months for Naval Intelligence to cross-reference Kovar’s position with captured Japanese logs. When the data finally aligned, the truth emerged: the 24-year-old in the blind wooden boat had accidentally decapitated a Japanese squadron.

Kovar was awarded the Navy Cross for “extraordinary heroism.” The citation praised his aggressive attack under fire but remained silent on the fact that his victory was a literal accident of physics.

EPILOGUE: THOUSANDTHS OF AN INCH

After the war, Isidor Kovar did something rare for a hero: he disappeared. He didn’t write a book. He didn’t run for President like John F. Kennedy (another PT boat veteran). He returned to civilian life and never sought the spotlight.

PT-137 was scrapped in 1946. No museum preserved the boat that fired the most significant shot in the history of the “Mosquito Fleet.”

But the legacy of that night remains a testament to the strange nature of war. A factory worker in Rhode Island made a mistake of five-thousandths of an inch. That mistake saved 12 American lives on PT-137 (who would have been obliterated by the destroyer had they actually hit it) and sent one of Japan’s most decorated cruisers to the bottom of the ocean.

Sometimes, the most “failed” weapon in the world is exactly what history requires.

Note: Some content was generated using AI tools (ChatGPT) and edited by the author for creativity and suitability for historical illustration purposes.