May 19th, 1944. Somewhere off the coast of New Guinea, a small American warship barely 300 ft long is closing on a contact her sonar operator swears is real. She’s not a fleet destroyer. She’s a destroyer escort or DE 635, the USS England or crew. A stopgap design the Navy had rushed into production because it didn’t have enough steel or manpower to build real warships fast enough.
She’s slower than a fleet destroyer, lighter armed, and crewed largely by reservists who’d never seen combat. On paper, she is exactly the kind of ship a Japanese submarine skipper should have laughed at. 12 days later, the England had sunk six Japanese submarines. Not damaged, not driven off, sunk.
No warship in history before or since has matched that record in that span of time. And she did it using a weapon that traditionalists in her own Navy considered a gimmick, a Mousetrap, a stubby spike-covered mortar that looked more like a piece of medieval siege equipment than a piece of 1940s ordnance. This shouldn’t have worked.
A weapon with a 5% success rate in its first year of combat should not have become the most efficient submarine killer of the Second World War. A ship class the Navy itself considered a stopgap should not hold a record that has stood for 80 years. But the England’s crew wasn’t using a better weapon than everyone else.
They were using an old idea built by someone else, refined and drilled into muscle memory by American crews. Oh, the Mousetrap. And that distinction, more than any single piece of hardware, is the whole story. For a quarter century, sinking a submerged submarine meant one thing, the depth charge.
Roll a steel drum of TNT off the stern, set a hydrostatic fuse for a guessed depth, and hope the resulting shockwave was close enough to crack the enemy’s pressure hull. Standard doctrine held that this was simply how it was done. The physics were straightforward, the manufacturing was cheap, and by 1943, American and British yards were turning out thousands of them.
But naval gunnery officers on both sides of the Atlantic knew the ugly secret behind the numbers. Across the war, out of 274 recorded British depth charge attacks, only 85.5 resulted in a kill or a uh a success ratio of roughly 60 to 1. Worse, the weapon had a built-in blind spot. Sonar of the era, uh over all, asdic to the British, sound gear to the Americans, asdic to the over all, worked by bouncing a ping off the target and timing the echo.
But, as a submarine closed inside a few hundred yards, the outgoing ping and the returning echo blurred into what sonar men called the instantaneous echo. The sub effectively vanished from the screen in the final seconds before the attacking ship passed overhead, weird spot, precisely when the U-boat or I-boat commander was making his last, sharpest evasive turn.
Standard doctrine called this the price of doing business. You dropped your charges on the last known bearing. You accepted that most attacks would fail, and you counted on there being enough holes and enough depth charges in the fleet that the arithmetic eventually worked out in your favor.
Critics who defended the depth charge argued that mass and patience would always win in the end. They were right that persistence mattered. What they were wrong about was assuming persistence meant throwing more steel at the problem, rather than throwing it more intelligently. A submarine skipper who understood the sonar blind spot could time his turn to the second, slip past the moment his hunter went deaf, and lived to attack another convoy.
Japanese and German crews both learned this trick early, and both came to treat a depth charge attack as survivable, provided they kept their nerve during those final blind seconds. The fix wasn’t a bigger charge. It was a smarter fuse. British engineers at the Directorate of Miscellaneous Weapons Development had spent years developing a forward-throwing mortar they nicknamed the Hedgehog because its bank of empty spigots looked like a hedgehog’s spines.
Instead of one large depth charge rolled off the fantail, the Hedgehog launched 24 separate mortar bombs, all burst throughs, each 7.2 inches across, weighing about 65 lb, packed with 30 to 35 lb of TNT or torpex, all burst throughs, arcing ahead of the ship in a rippling salvo. They landed in an elliptical pattern roughly 100 ft long, spaced closer together than the width of a submarine’s hull, about 200 to 275 yd in front of the bow.
The secret was in the fuse, not the explosive. Every bomb was contact fused. It would not go off from proximity, water pressure, or a preset timer. It detonated only when it physically struck something solid, a war bow, a submarine’s hull. That single design choice solved two problems at once. First, because the weapon fired forward while the ship still had the target on sonar, there was no blind period.
The attacking ship never lost contact in the final seconds, the way she did rolling depth charges off the stern. Second, a miss made no explosion at all, which meant sonar operators could immediately reset and try again without the ocean full of noise and turbulence a depth charge attack always left behind. Oh, well.
Noise that could take 15 minutes to settle before the sub could be relocated. The Americans took the British concept and hardened it. The US version, built from late 1942 onward, used a sturdier mounting, a gun train indicator, and a target designation transmitter that let the sonar operator and the gun crew stay synchronized in real time, translating a bearing and range straight into a firing solution without a slide rule or plotting table in between.
Reloading took about 3 minutes with a trained crew of eight. Because the mortar’s firing sequence was staggered on one or two, its four cradles of six spigots each triggered in pairs a fraction of a second apart. The recoil never stressed the deck enough to require structural reinforcement.
That last detail mattered enormously because it meant a Hedgehog projector could be bolted onto almost any hull the Navy already had sitting in a shipyard, including small, mass-produced destroyer escorts that were never designed from the keel up as dedicated submarine killers. What looked like a modest, unglamorous mortar was actually a plug-and-play upgrade that could turn a stopgap escort into a genuine hunter-killer in the time it took a yard crew to weld a mount to the foredeck.
There was a second, less visible half of the trick, training. The Navy built dedicated attack teachers, uh Volvos, mechanical simulators that let a sonar team and bridge crew rehearse dozens of approaches against a simulated contact without burning a single live round. A crew could run an attack, learn exactly where their salvo would have landed relative to the target, correct their timing, and run it again within minutes.
That repetition was cheap and fast, and it built the one skill that actually decided whether a Hedgehog salvo hit or sailed harmlessly past, knowing precisely when, not just where, to pull the firing key. A destroyer escort with a green crew and a Hedgehog mount wasn’t a submarine hunter yet.
That same crew, after a few weeks of attack teacher drills, was. By May 1944, Japanese Admiral Soemu Toyoda needed to know where the next American blow was going to fall. Uh we asked her, the Marianas or the Palaus? Uh her row. And he strung a picket line of submarines across the approaches to find out. He had every reason to think that line would hold.
Submarine scouting lines were a proven tool, and the small American escort vessels patrolling those waters didn’t look like a serious threat. He was wrong. Commanded by Lieutenant Commander Walton B. Pendleton, the USS England picked up her first submarine contact on May 19th and put it down with a single Hedgehog salvo. Over the following 12 days, she did it again and again four more times.
Six Japanese submarines in all, wrecking Toyoda’s entire scouting line before it could report a single sighting. On one attack, when the target tried to swing away at the last second, Pendleton simply led the turn and fired anyway. Uh her row. Two Hedgehog projectiles struck home. The ship rocked from the underwater blast, and debris that included Japanese lettered bottle corks and varnished hardwood came up in the wash.
There was no ambiguity about what a hit sounded like or looked like. That was the whole point of a contact fuse. An explosion meant to kill, not a guess. Compare that to what depth charges alone could produce against a determined, well-built submarine. In April 1945, the German U-427 survived 678 depth charges dropped against her in a single engagement and made it home.
678 explosions, hours of pursuit, an entire escort group’s worth of ordnance expended, and the boat lived. The England needed one accurate salvo per kill, delivered in the space of a single sonar approach, a matter of minutes from contact to explosion, not hours of dropping ordnance and hoping cumulative damage eventually cracked the hull.
Where a depth charge crew had to wonder, after every splash, whether they’d even come close, an England lookout knew a kill the instant he heard it. A single, sharp underwater crack, distinct from the softer, rolling boom of a depth charge going off on schedule, regardless of whether anything was underneath it.
The England was awarded the Presidential Unit Citation, and naval historians still call her 12-day run unmatched in the history of anti-submarine warfare. She wasn’t an isolated case, either. Across the Pacific and the Atlantic, other lightly-built destroyer escorts fitted with the same mortar began putting up kill numbers that outpaced ships twice their size and displacement, simply because the weapon didn’t care how big or fast the platform carrying it was.
What mattered was whether the crew behind it had learned to trust their sonar contact all the way through the final turn, instead of flinching early and firing wide. None of this happened by accident, and it didn’t happen instantly, either. When the Hedgehog was first installed across a hundred Royal Navy ships in 1942, it sank nothing for months.
Early combat success rates hovered around 5% or so, barely better than the depth charge it was supposed to replace. Commanders weren’t wrong to be skeptical at first. The weapon demanded something depth charges never had, precision aiming, because a miss meant nothing happened at all, with no consolation blast to shake the target or boost morale.
But, once sonar operators and gun crews trained properly, they using the ship’s actual detection gear, rather than treating the mortar as a bolt-on afterthought, as in will show it all, the picture flipped completely. By the war’s end, roughly one in five Hedgehog attacks scored a kill, compared with something close to one in 60 for conventional depth charging.
The weapon’s real advantage was never raw explosive power. A Hedgehog bomb carried a fraction of the Torpex a full-size depth charge carried. And what made it work was that it eliminated guesswork from the equation. And guesswork, all right, Jules, not tonnage of explosive or was the reason skilled submarine commanders had been surviving depth charge attacks for years.
This is why the England’s 12 days weren’t a fluke of luck, but a demonstration of a doctrine finally matching technology. American destroyer escorts weren’t dramatically better warships than the Japanese vessels hunting the same waters. They were ordinary mass-produced hulls carrying a weapon whose entire design philosophy was confirm, don’t guess.
Fit it to a ship, train the crew to trust their sonar contact all the way to the moment of firing instead of breaking off early. And even a hastily built wartime escort became lethal within minutes of making contact. It’s worth being honest about where credit belongs. The Hedgehog wasn’t an American invention or what a mouse.
It came out of British wartime research, tested first aboard HMS Westcott, and rushed into Royal Navy service after a demonstration for Winston Churchill himself. The trick wasn’t inventing the weapon. It was what the US Navy did with it afterward, hardening the mounting, wiring in a target designation system that closed the loop between sonar and gun crew, mass producing it onto the cheapest, fastest to build escort hulls in the fleet, and then drilling ordinary reservists on attack teams until firing the thing at the right instant became reflex instead of guesswork. The combination, Boris true, borrowed hardware, American manufacturing scale, and relentless simulator training and is what led a 300-ft stopgap ship outhunt purpose-built destroyers three times her size. Battlefields all follow her and Battlewater star don’t reward the weapon that looks most impressive sitting stationary on a test range. They reward the one that keeps working when the target is turning, the sonar is jittery, and the crew has 30 seconds to decide. The Hedgehog, adapted, ruggedized, and drilled into American destroyer escort crews, was exactly that
weapon. And for six Japanese submarines in the early summer of 1944, it turned out to be the last thing they ever heard.
Disclaimer : This content may be created by AI for entertainment purposes. Any resemblance to real persons, events, or places is coincidental.
