August 7th, 1943. Mid-Atlantic, 600 miles west of the Azores. Two German submarines sat motionless on the surface, side by side, connected by a rubber hose. U-117, a large mine layer, was pumping fuel into U-66, a type 9 attack boat that had been wounded 4 days earlier by American aircraft.
U-117 had also sent her doctor across by inflatable raft. Several of U-66’s crew were injured, one badly. The sea was calm. The nearest land was a thousand miles away. The nearest Allied airfield was further still. There was no reason for an airplane to be here. Lieutenant Junior Grade Asbury Salinger saw them first.
Flying a Grumman Avenger at 3,000 feet, he was 60 miles from his ship, a ship most German submariners didn’t know existed. Salinger pushed his stick forward and dove toward the two dark shapes on the water. He had no fighter escort. He attacked alone. His depth charges straddled U-117. The explosion sent a column of white water between the two boats and severed the fuel hose.
Both submarines began to separate, their crews scrambling across wet decks toward anti-aircraft guns. But Salinger had already radioed his carrier. Within 25 minutes, five more Avengers and four Wildcats arrived. U-66 crash dived and escaped into the deep. U-117 was not so fortunate. A torpedo, a weapon the Germans didn’t know existed, one that could hear the sound of their propellers underwater, found her hull.
62 men went to the bottom. None survived. The aircraft that killed them had launched from the flight deck of USS Card, a ship built from a cargo freighter hull, displacing less than a tenth of what U-117’s crew believed an aircraft carrier should weigh. The pilot who found them was 24 years old. The torpedo that killed them was powered by a motor designed for a washing machine.
And the men who ordered U-117 to that exact position at that exact time had done so using radio signals that they believed were unbreakable. If this story matters to you, if you want these histories to reach the people who grew up with them, a like and a subscribe go further than you think. Here is what makes this story different from almost everything you have heard about the Battle of the Atlantic.
For 3 and 1/2 years from September 1939 to the spring of 1943, the German U-boat was the most feared weapon in the ocean. It operated on a simple principle: surface at night, find a convoy, fire torpedoes, disappear. The Atlantic was vast and dark and largely empty of aircraft. A submarine that stayed below the horizon was functionally invisible.
Wolf packs, groups of eight, 12, sometimes 20 U-boats would converge on a single convoy and tear it apart over three or four nights. The merchant sailors who survived described the experience as being hunted by something they couldn’t see, couldn’t hear, and couldn’t fight. By March 1943, Admiral Karl Dönitz had more than 400 U-boats in commission.
Over 120 were at sea on any given day. That month, his boats sank 120 Allied ships, nearly 700,000 tons of cargo, fuel, food, and ammunition that would never reach Britain. There was a stretch of open ocean between Greenland and Iceland, 600 to 800 miles wide, where no Allied aircraft could reach. The submariners called it their safe zone.
The British Admiralty called it the air gap. And inside that gap, convoys were on their own. Hold that fact, the air gap, because what happened next is one of the fastest reversals in the history of naval warfare. And it started not with a battleship, not with a fleet carrier, not with a new submarine of their own, but with a ship that most American sailors considered a joke.
She was 512 ft long. She could make 19 knots on a good day. Her flight deck was so narrow that pilots called landing on it a controlled crash. She had been built in a commercial shipyard on a cargo hull in less than a year. She carried no armor. A single torpedo would have broken her in half.
The US Navy designated her an escort carrier, CVE. The men who sailed her had other names, combustible, vulnerable, expendable. That’s what the initial stood for, they said. The Navy built them by the dozen, then by the score, then by the hundred. They were the smallest carriers afloat, and no one in Berlin took them seriously.
No one in Berlin understood what they were for, because these ships were not built to fight naval battles. They were not designed to project power across oceans. They were built for one purpose, to find German submarines and kill them. Not by defending convoys, not by waiting for an attack, by hunting, by going into the open Atlantic with a handful of destroyer escorts and a squadron of aircraft and staying there days, weeks, until every U-boat within 200 miles was on the bottom or running for home.
The Germans had a word for what followed. They wrote it in their war diaries, in their patrol reports, in their letters home, in the trembling answers they gave to Allied interrogators after being pulled from the sea. And when you read what they wrote, the captains, the engineers, the 19-year-old torpedo mechanics, you can trace the exact moment when the hunters realized they had become the hunted.
But to understand what those words mean, you have to understand what they lost first. And that begins with a number that Dönitz carried in his head like a prayer, 700,000 tons per month. That was the number. Dönitz calculated it in 1940, refined it in 1941, and by 1942, he had made it the central equation of Germany’s war at sea.
If his U-boats could sink 700,000 tons of Allied shipping every month, consistently, month after month, Britain would starve, not metaphorically. The island imported 70% of its food, nearly all of its oil, and every bullet fired by every soldier in every theater of the war. Cut the convoys and the war was over. Dönitz was not guessing.
He had built a system to deliver that number. He called it Rudeltaktik, pack tactics. Though the Allies would give it a more famous name, wolfpack. The principle was elegant. A line of U-boats, spread across 50 or 100 miles of ocean, would wait for a convoy to cross their path. The first boat to spot smoke on the horizon would not attack.
It would shadow the convoy and transmit a contact report to Dönitz’s headquarters in Berlin. Dönitz would then vector every available boat toward the intercept point. They would converge at night, attack from multiple directions simultaneously, and overwhelm the escorts. It worked because of mathematics.
A convoy escort group in early 1943 typically had six or seven warships guarding 30 to 60 merchant vessels stretched across miles of ocean. A wolfpack of 15 U-boats attacking from all sides at night created more threats than the escorts could answer. For every U-boat an escort chased, two more slipped through. And at night, on the surface, a U-boat was almost impossible to detect.
She was low in the water, painted gray, running on diesel engines that left no wake. Radar in 1942 could barely find her. Sonar was useless against a surface target. Human eyes scanning a black horizon were the convoys’ best defense, and they were not enough. The results were staggering. In 1942, U-boats sank over 6 million tons of Allied shipping.
In the first 20 days of March 1943, remember this number, they sank 82 ships in the Atlantic alone, 476,000 tons in 3 weeks. The worst single battle was fought over convoys HX 229 and SC 122 in mid-March. 63 merchant ships sailing from New York to Liverpool ran into three wolf packs totaling 43 U-boats. Over 4 days, 22 ships went down.
Oil tankers split in half and burned on the surface for hours. Freighters loaded with grain and ammunition broke apart so fast their crews had no time to reach lifeboats. 146 merchant sailors died in water so cold it killed a man in 4 minutes. In Berlin, the daily war diary of the U-boat command, the Befehls Haber der Unterseeboote, or BDU, recorded the tonnage figures with something close to satisfaction.
Dönitz briefed Hitler personally. The Führer, who understood almost nothing about naval warfare, understood that number, 700,000 tons. His submarines were approaching it, and every one of those attacks happened inside the air gap. That stretch of open Atlantic where no Allied aircraft could reach was the wolf pack’s sanctuary. U-boats could surface there in daylight, charge their batteries, transmit without fear, and wait.
A submarine that stayed submerged moved at four knots, walking speed. On the surface, she could make 17. Submersion was survival, but it was also blindness. A U-boat underwater could not find a convoy. She had to be on the surface to hunt, and the only thing that forced her down was an airplane. In the air gap, there were no airplanes. Dönitz knew this.
He built his entire strategy around it. Every wolf pack he assembled, every patrol line he drew across the chart, was positioned inside those 600 miles of open water where his boats could operate on the surface without fear of attack from above. The system depended on one assumption that he never questioned. Aircraft carriers belonged to the Pacific, to fleet battles, to the enormous blue water engagements between Japan and the United States.
No one would waste a carrier hunting submarines in the middle of the Atlantic. And even if someone tried, a real carrier was too valuable, too slow to build, too important to risk against a torpedo that cost a fraction of its price. He was half right. No one would send a fleet carrier, but here is the fact that Dönitz did not have in his equation, the fact that would turn the number he worshipped into the number that killed his men.
By the spring of 1943, American shipyards had figured out how to build an aircraft carrier in less time than it took Germany to train a single U-boat crew. Not a fleet carrier, something smaller, something expendable, something that could be produced so fast and so cheaply that the United States could afford to lose them.
And Germany could not afford to ignore them. The first of these ships was already at sea. She was called USS Bogue. She had sailed from Argentia, Newfoundland, on the 5th of March, 1943, with 12 Wildcats and eight Avengers on her deck, screened by two old destroyers from the last war. Her crew included survivors from Lexington and Yorktown, men who had watched real carriers burn and sink beneath them.
Now they were flying off a converted cargo ship in the North Atlantic in winter. Nobody aboard Bogue knew they were about to change the war, and nobody in Berlin knew they existed. But there was a problem. Because knowing how to build these ships was not the same as knowing how to use them.
And the first man who figured that out nearly got himself killed in the process. Bogue’s first three crossings were a disaster, not the kind of disaster that sinks ships, the kind that makes admirals question whether the entire concept is worth the fuel. In March 1943, Bogue sailed with convoy HX 228 toward Liverpool.
Her pilots flew patrol after patrol into gray skies and freezing rain. On the 10th of March, Ensign McCausland spotted a U-boat on the surface, the first submarine any of Bogue’s pilots had ever seen outside of training. He dove to attack. His depth bombs failed to release. He came around for a second pass. They failed again. The U-boat slipped beneath the surface and disappeared.
Bogue detached from the convoy the same day. After she left, the wolves found it. Ships went down. She tried again with convoy SC 123 later that month. No contact, no attacks, no result. She tried a third time. Nothing. Bogue returned to Argentia, then limped to Boston to repair a broken catapult. Her pilots had flown dozens of sorties in some of the worst weather on Earth and had not scratched a single U-boat.
The problem was not courage. The problem was doctrine. In the spring of 1943, escort carriers were assigned to convoys the same way destroyers were, as shields. They sailed with the merchant ships, flew patrols in a tight circle around the formation, and waited for the enemy to come to them. This meant the carrier was always where the convoy was, which was exactly where the U-boats expected to find aircraft.
The submarines simply waited until the planes returned to refuel, then attacked in the gap. It took three crossings for the Navy to understand what one captain had been arguing since the day he took command. His name was Arnold Isbell. Most people called him Buster. He was 43 years old from a small town in Iowa, and he had been flying Navy aircraft since 1924.
Back when the Navy’s first carrier was an old collier with a wooden flight deck bolted on top. Isbell took command of USS Card on April 17th, 1943, and from his first day aboard, he told anyone who would listen that the escort carrier was being used wrong. The CVE was not a bodyguard, he said. It was a hunter.
You didn’t keep it tethered to a convoy like a dog on a leash. You turned it loose. You sent it into the open Atlantic with its own escorts, gave it intelligence on where the U-boats were gathering, and let it go find them. Remember that idea, because everything that follows, every German war diary entry, every terrified interrogation transcript, every desperate signal from a U-boat captain who could not understand how he was found in the middle of an empty ocean, traces back to that single shift in thinking, defense to offense, shield to spear. But Bogue
got there first, not because her captain invented the concept, but because Black May forced the Navy’s hand. By the third week of May 1943, the Atlantic was a slaughterhouse, and for the first time, the bodies were German. 43 U-boats were sunk that month alone. 25% of every operational submarine Dönitz had.
18 were killed in convoy battles. 14 were caught by aircraft on patrol. The escorts had new radar that could find a submarine’s periscope in heavy seas. Coastal Command Liberators were reaching deeper into the air gap. And the U-boats, following Dönitz’s own order to stay on the surface and fight back against attacking aircraft with anti-aircraft guns, were dying on the surface instead.
On May 22nd, with Wolfpack Mösel still clawing at convoy ON 184, Bogue finally drew blood. Lieutenant Junior Grade William Chamberlain, flying an Avenger, caught U-569 on the surface and put two depth charges close enough to crack her hull. The captain ordered his crew topside and scuttled the boat.
24 survivors were pulled from the water by a Canadian destroyer. It was one submarine, but it was proof. Two days later, on May 24th, Karl Dönitz sat at his headquarters in Berlin and made the hardest decision of his war. He ordered every wolfpack out of the North Atlantic. The war diary entry is quiet, controlled. It attributes the catastrophe to the superiority of enemy detection equipment and the surprise from the air which that equipment made possible.
It does not mention that among the 43 boats lost that month was U-954, a brand new Type 7C on her first patrol. Dönitz does not mention that boat in his memoirs either. Her watch officer, the young man standing beside the captain when the depth charges found them, was named Peter Dönitz. He was 21. He was the admiral’s younger son.
Dönitz pulled his boat south toward the Azores, toward the coast of Africa, toward the routes where the air cover was thinner and the convoys less protected. He told himself and his commanders that this was temporary, that new weapons would restore the balance, that the wolf packs would return.
What he did not know, what he could not have known, was that the retreat solved nothing because the Americans were not waiting for the wolf packs to come back. They were coming after them and the man leading the hunt had just left Norfolk, Virginia on the 27th of July aboard a converted cargo ship with a flight deck, three old destroyers for escort, and a squadron of pilots who had never seen combat.
Buster Isbell had his chance and within 11 days the Atlantic would belong to a different kind of hunter. Card sailed from Norfolk on July 27th, 1943 with 12 Avengers and nine Wildcats of Composite Squadron One on her deck. Her escorts were three flush deck destroyers from the First World War, old four stackers, thin-skinned, built in 1918.
The youngest ship in the group was the carrier herself and she had been a bare steel hull less than a year earlier. Captain Isbell did not sail toward a convoy. He sailed toward a set of coordinates that had been handed to him in a sealed envelope before departure. Those coordinates came from a place that Isbell was not told about, a place that did not officially exist, a brick building in Washington where Navy cryptanalysts were reading German radio traffic almost as fast as Dönitz’s own staff. The program was called Ultra, and
what Ultra had decoded was something the Germans considered unbreakable, the schedule and position of their next submarine refueling rendezvous. Here is what you need to understand about the refueling system because it was the spine of Dönitz’s entire Atlantic campaign. A standard type 7 U-boat carried enough fuel for roughly 45 days at sea.
A round trip from France to the mid-Atlantic convoy lanes burned most of that fuel just getting there and back, leaving barely 2 weeks on station to hunt. Dönitz’s solution was the type 14 supply submarine, the Milchkuh, the milk cow. These were enormous boats, 1,600 tons, carrying enough diesel to refuel a dozen smaller submarines at sea.
They also carried torpedoes, food, fresh water, spare parts, and a doctor. A single milk cow could keep an entire wolf pack operational for weeks beyond its natural endurance. By the summer of 1943, the milk cows were the most important submarines in the Atlantic. Without them, Dönitz could not sustain operations anywhere south of the Azores or west of the mid-Atlantic Ridge.
Every attack boat that sank a freighter off Brazil, off West Africa, off the Caribbean, depended on a milk cow rendezvous to get home, and every one of those rendezvous required a radio signal. Dönitz transmitted the coordinates by Enigma cipher. The U-boats acknowledged by Enigma cipher. Both signals were intercepted, decoded, and forwarded to the 10th Fleet in Washington, Admiral Ernest King’s dedicated anti-submarine command, which plotted the position on a chart and sent an escort carrier to meet them.
The trick was timing. If the hunter-killer group arrived too early, the U-boats would not yet be there. Too late, and they would have scattered. The group had to appear at the exact moment when two submarines were sitting motionless on the surface, connected by a hose, unable to dive.
On August 7th, 11 days into Card’s first offensive cruise, Lieutenant Junior Grade Asbury Salinger found exactly that. You already know what he saw. Two submarines side by side, 600 miles from the nearest land. U-117, a large mine layer pressed into service as a provisional tanker, transferring fuel and her ship’s doctor to the wounded U-66.
Salinger dove alone and attacked. But now you know what he knew before he pushed his stick forward. Those boats were supposed to be there. The coordinates were not a lucky guess. They were a decoded German signal transmitted four days earlier, received and plotted at 10th Fleet headquarters, and relayed to Card by encrypted dispatch.
U-117 never completed her mission. She went down with all 62 hands, and within three weeks Card’s pilots sank three more submarines. U-664 on August 9th, U-525 on August 11th, and on August 27th, the big one, U-847. U-847 was the last available provisional tanker in the Central Atlantic. She had refueled six U-boats that morning.
Hours later, two Wildcats from Card strafed her on the surface and forced her to dive. Lieutenant Junior Grade Ralph Long dropped a weapon into the water just ahead of the swirl where she had submerged. Three minutes later, the ocean erupted. U-847 went down with all 63 men. In four weeks, Isbell’s group had killed four submarines and crippled the entire Mid-Atlantic refueling network.
The milk cow that was supposed to supply a dozen attack boats was gone. The boats she was meant to refuel were now stranded, burning through their reserves, unable to reach their patrol areas, forced to crawl home on fumes. One dead tanker meant 12 patrols canceled. Two dead tankers meant a theater shut down. By the end of 1943, escort carrier groups had sunk five of the 10 milk cows.
Within a year, all 10 were on the bottom. Not one survived the war. 289 of their crewmen were killed. They had the highest casualty rate of any submarine type in the Kriegsmarine. Dönitz knew he was losing his supply chain. His war diary entries from August and September reflect a man grasping for explanations.
His boats were being found at coordinates that should have been secret. His rendezvous points were compromised before his submarines could reach them. He suspected treachery. He suspected spies. He investigated his own staff. What he never suspected, what he refused to believe until the evidence was placed in front of him at Nuremberg, was that his cipher had been broken.
But the cipher was only half the weapon. Knowing where a U-boat would surface was useless without something that could kill it after it dove. And Card’s pilots had been carrying that something in their bomb bays since July. A weapon so secret that the United States Navy refused to call it what it was. They called it a mine. It was not a mine.
In December 1941, 3 days before Pearl Harbor, a group of physicists and engineers gathered at Harvard University’s underwater sound laboratory to discuss something that had never been built. A torpedo that could hear. The concept was simple. An airplane catches a submarine on the surface. The submarine dives, which is what submarines have done since submarines existed.
The airplane drops a weapon into the water at the point where the submarine disappeared. But instead of sinking to a preset depth and exploding like a depth charge, which required the pilot to guess exactly where the submarine would be, and which missed far more often than it hit, this weapon would listen. Four hydrophones embedded in its nose would detect the sound of the submarine’s propellers turning underwater.
A vacuum tube guidance system would steer the torpedo toward that sound. The submarine could turn, could change depth, could run silent. But as long as her screws were spinning, the weapon would follow. The Navy gave the project a code name, Fido. They classified it as a mine, Mark 24 mine, to keep the Germans from knowing what it actually was.
The deception held for the entire war. German intelligence never identified it. German engineers never reverse-engineered it. German submariners who survived its attacks never understood what had hit them. The speed of its creation was something that could only have happened in America in 1942. Bell Telephone Labs designed the guidance system.
Harvard built the acoustic sensors. General Electric provided the propulsion motor, a 5 and 1/2 horsepower electric engine originally manufactured for household washing machines. Western Electric produced the batteries. David Taylor Model Basin handled the hydrodynamics. Four separate organizations, working in parallel with complete information sharing, built a weapon that had never existed before.
The first prototype was test-fired on December 7th, 1942, the first anniversary of Pearl Harbor. It worked. Three months later, production models were rolling off the line. By May 1943, Fido was at sea aboard escort carrier aircraft, 17 months from first concept meeting to first submarine killed. In the modern American defense establishment, a comparable weapon takes 10 to 15 years.
Now, imagine you were a German submarine commander in the autumn of 1943. You have been told that the mid-Atlantic is dangerous, that aircraft are everywhere, that milk cows are being sunk. But you are a veteran. You have survived 12 patrols. You know the drill. When an airplane appears, you sound the alarm, clear the bridge, and dive.
60 seconds, maybe 90, and you are under the surface. The airplane drops depth charges where it thinks you are. But you have already turned, changed course, gone deep. The charges explode behind you, above you, to the left. The hole groans, the lights flicker, but you are alive. You have done this before.
Depth charges are a lottery, and the odds favor the submarine. Except now, something is different. You have dived on schedule. You have turned hard to port and gone to 150 m. The depth charges are detonating far behind you, nowhere close. You are safe. And then, 3 minutes after the last explosion, in silence, from a direction you did not expect, something hits your stern.
Not a depth charge. Something that found you. Something that followed you through your turn, through your depth change, through your evasive pattern. Something that was listening. This is what Fido did to the mathematics of submarine warfare. Before Fido, the survival rate for a U-boat that crash dived before depth charges fell was better than 90%.
After Fido, the odds collapsed. The Mark 24 mine sank 37 submarines and damaged 18 more out of 204 fired, an effectiveness rate of 22% more than double that of conventional depth charges. And because the Germans did not know it existed, they could not develop countermeasures. They could not deploy decoys. They could not change tactics to avoid a weapon they did not believe was real.
Every escort carrier in the Atlantic carried Fido from the summer of 1943 onward. The Avenger torpedo bombers of composite squadrons flying off Bogue, Card, Core, Croatan, Block Island, and Guadalcanal dropped them into the Atlantic with the mechanical regularity of an assembly line.
An Avenger would arrive over a diving submarine, wait for the swirl to settle, and release Fido at 200 ft altitude and 120 kn. The torpedo entered the water, began a slow spiral search, and waited for sound. If the submarine’s propellers were turning, and they always were because a submarine that stopped her screws would sink, Fido found her.
The weapon cost $1,800 per unit. A type 7 U-boat cost 4.7 million Reichsmarks to build and took 10 months to complete. Her crew of 44 to 52 men represented 2 years of training. Fido killed them with a motor designed to wash clothes. Here is what makes this detail matter for the story we are following.
By the end of 1943, the American hunter-killer system had three components that the Germans could not see and could not counter. Ultra told them where the submarines would surface. The escort carrier put aircraft over that position, and Fido killed the submarine after it dove. Surface, and the aircraft finds you. Dive, and the torpedo follows you.
Stay where you are, and the destroyer escorts close in with sonar and hedgehog mortars. There was no correct answer. And the men trapped inside those steel hulls knew it, because by the autumn of 1943, the things German submariners were writing in their logs had changed. In the early months of the war, when a U-boat returned to port in Lorient or Brest or Saint-Nazaire, the captain would stand on the bridge while the crew lined the deck and a brass band played on the quay.
Pennants flew from the periscope, one for each ship sunk. Officers received Iron Crosses from Dönitz himself, who came to the docks personally, shook every man’s hand, and asked about the patrol. The crews were young, many of them under 25, and they carried themselves with the confidence of men who believed they were winning the war.
They called themselves volunteers. They called their boats gray wolves. By the autumn of 1943, the bands had stopped playing. British intelligence was intercepting and translating prisoner of war interrogation reports as fast as captured crews could be processed. The change was visible in the transcripts. In 1941 and 1942, captured U-boat officers had been defiant.
They boasted about their tonnage, quoted Dönitz’s speeches, insisted that Germany’s submarines would strangle Britain. By the summer of 1943, the tone was different. A report from June noted that recent prisoners were, as British officers recorded, dejected, though relieved to be out of the Battle of the Atlantic. The overwhelming confidence of earlier crews was disappearing.
They had reason to be afraid. Between September and October 1943, 25 U-boats were sunk in the Atlantic. In return, they managed to torpedo nine merchant ships. Nine. For 25 submarines and roughly 1,200 men, the exchange rate had inverted so completely that every patrol was now a net loss for the Kriegsmarine.
A U-boat that left port had a one in four chance of never returning. By late 1943, that number would worsen to one in three. By 1944, it approached one in two. Dönitz knew his crews were breaking. He could see it in the patrol reports, boats returning early with mechanical failures that may or may not have been real. He could see it in the signals, captains reporting that they had been forced under by aircraft and were unable to surface when their position suggested no aircraft were near.
He could see it in the faces of the men he debriefed. Men who had once begged for combat patrols and now stood before him with the eyes of people who had already calculated their own odds. He tried to hold them. He distributed medals faster than ever before. A decoration for every man who completed a patrol, because a man who had done well should not go to sea unrewarded, as he would later explain at Nuremberg.
He urged his captains to show a hunter’s instinct and warrior spirit in the face of the Allied air threat. He told them new weapons were coming, acoustic torpedoes, radar detectors, faster boats. Hold on, he said, the technology will catch up. It did not catch up. In September 1943, Dönitz sent his wolf packs back into the North Atlantic equipped with acoustic torpedoes, the T5 Zaunkönig, designed to home on the propeller noise of escort ships.
The first attacks against convoys ONS 18 and ON 202 sank three escorts and six merchant ships. For 48 hours it looked like the wolf pack had returned. Then the allies deployed Foxer, a towed noise maker that drew the acoustic torpedoes harmlessly into the wake behind the ship. Within weeks the Zaunkönig was neutralized. The wolf packs that Dönitz had reassembled with such desperate hope were destroyed.
More boats went down, more crews did not return, and the Navy was forced to cross a line it had never crossed before. Since the founding of the U-boat arm, submarine service had been voluntary. Every man aboard a U-boat had asked to be there. By the end of 1943 that was no longer true. Rear Admiral Francis Low, chief of the American 10th Fleet, reported publicly in September that the German Navy was nearing demoralization similar to 1917, and had already been forced to draft U-boat crews. The men climbing through
the hatches of boats leaving Brest and Bergen were no longer volunteers. They were conscripts, men who had been told, not asked, to enter what their own sailors had begun calling the iron coffin. The numbers tell the rest. Over the course of the war, roughly 40,000 men served in German submarines. 30,000 of them, 75%, were killed.
It was the highest casualty rate of any branch of the German armed forces. Higher than the Waffen SS, higher than the Luftwaffe’s night fighter pilots, higher than the Wehrmacht divisions that bled out on the Eastern Front. Three out of every four men who boarded a U-boat did not survive the war.
And the instrument that killed more of them than any other single weapon system was the American escort carrier hunter-killer group. By the Navy’s own accounting, CVE groups were responsible for approximately 60% of all U-boats sunk by American forces in the Atlantic between April and September 1944. Not shore-based aircraft, not fleet destroyers, not minefields, escort carriers.
The ships the Germans had dismissed as insignificant, built on cargo hulls, flown by pilots who had never seen a fleet engagement. Dönitz’s war diary from October 1943 contains an entry that his staff could barely bring themselves to write. “The enemy’s attempts to restrict our operations,” it reads, “have succeeded.” Eight words, no excuses, no promises of new weapons, but there was one thing left that Dönitz believed the Americans could never do.
One humiliation that the entire German submarine command considered so unlikely that they never trained their crews for the possibility. They were wrong. And the man who proved them wrong was already at sea aboard another converted cargo ship rehearsing something that had not been done since 1815. June 4th, 1944. 150 mi west of Cape Blanco, French West Africa.
Two days before the invasion of Normandy and 5,000 mi from Omaha Beach, a different kind of American operation was underway. USS Guadalcanal had been at sea for 3 weeks without a contact. Her task group, five destroyer escorts and a single escort carrier, had been hunting U-boats off the African coast and the ocean had given them nothing.
Captain Daniel Gallery, commanding from Guadalcanal’s bridge, was low on fuel and overdue in Casablanca. He had just ordered his group to reverse course when the destroyer escort Chatelaine’s sonar operator reported a contact. Bearing was 210°, range was close. Gallery did not hesitate.
He launched two Wildcats and an Avenger and ordered Chatelaine to attack. The submarine was U-505, a Type 9 C boat returning home after an 80-day patrol in the Gulf of Guinea. She had been at sea so long that her crew had forgotten what land smelled like. Her captain, Oberleutnant Harald Lang, was making his first patrol in command. He was 36 years old and he had inherited a cursed boat.
U-505 had already lost two previous commanders. One relieved for psychological breakdown, another shot by his own crew in a struggle on the bridge. Chatelaine dropped her first pattern of depth charges. The explosions shook U-505 but did not kill her. The second pattern was closer. Relief valves blew across the boat.
Pipes cracked in the engine room. The whole rolled so far onto her beam that men were thrown from their stations. Shouts of panic came from the after compartments. Water was coming in. The rudder was jammed. The auxiliary controls were gone. Lang made a decision in seconds. He ordered his crew to blow tanks and abandon ship.
The submarine erupted to the surface barely 700 yards from Chatelaine’s bow, her conning tower streaming seawater, her crew already climbing through the hatches and jumping into the ocean. Wildcats overhead strafed the deck to keep anyone from manning the guns. One German sailor was killed, the only fatality.
The rest went into the water. What happened next was something the German submarine command had considered so improbable that they had never issued procedures for it. Gallery had been planning for this moment since January. After his task group had sunk three U-boats on previous cruises, U-544, U-515, and U-68, he had returned to Norfolk and ordered every ship in his group to prepare a plan for capturing a U-boat at sea.
Boarding parties were assembled, procedures were rehearsed, grappling hooks and tow lines were staged on deck. Gallery had authorization from the Navy to attempt what had not been done by American sailors in 129 years. USS Pillsbury lowered a whaleboat. The boarding party was led by Lieutenant Junior Grade Albert David, a 22-year-old from Maryville, Texas.
David had no way of knowing whether the submarine was booby-trapped. He had no way of knowing whether armed Germans were still inside. He had no way of knowing whether the boat was sinking beneath him as he climbed down the ladder into the conning tower hatch. He went anyway. Inside, David and his men found the boat abandoned but still running, her electric motors turning, her rudder jammed, water pouring in from a single open strainer valve.
One German sailor, a mechanic named Hans Göbler, had been the only crew member with the presence of mind to try to scuttle the boat. He had opened one valve. It was not enough. David’s team closed it, stopped the flooding, and shut down the engines. A larger salvage party arrived from Guadalcanal, led by Commander Earl Trosino, the carrier’s chief engineer.
Within hours, they had stabilized the boat and attached a tow line. Guadalcanal towed U-505 2,500 mi to Bermuda. The captured submarine yielded codebooks, Enigma settings, acoustic torpedo manuals, grid charts, and operational documents that Allied intelligence would exploit for the rest of the war.
The crew, 58 men, were taken aboard Guadalcanal and held in complete secrecy. For the remainder of the war, the German Navy believed U-505 had been sunk with all hands. They never knew she had been captured. They never changed their codes. Albert David received the Medal of Honor, the only one awarded in the Atlantic Fleet during the entire war.
Gallery received the Distinguished Service Medal. The task group received a presidential unit citation. The citation’s language is restrained. It does not mention that Gallery’s sailors fought the Germans on the submarine’s deck. It does not mention that David went down that hatch knowing he might not come back up. U-505 sits today in the Museum of Science and Industry in Chicago. You can walk through her hull.
You can stand in the control room where David stood. You can put your hand on the valve that Goebeler opened. 49 ft of steel, 700 mi from the nearest ocean. Preserved in a climate-controlled building visited by school children who do not know that the boat they are touching was the last enemy warship captured at sea by the United States Navy.
The capture confirmed what the interrogation reports, the war diaries, and the patrol logs had been saying for months. By the summer of 1944, the German submarine force was no longer fighting to win. It was fighting to survive. And Karl Dönitz, who had built that force from three boats in 1935 to 400 in 1943, already knew the words he would use to explain what had destroyed it.
On the 6th of May, 1944, 9 months after she escaped the attack that killed U-117, U-66 surfaced in the darkness, 400 mi west of the Cape Verde Islands. She had been hunted for 5 days by aircraft from a new escort carrier, USS Block Island, and she was trying to run on the surface under cover of night.
The destroyer escort USS Buckley found her. What followed was the kind of battle that belongs to a different century. Buckley closed at flank speed and rammed U-66 amidships. The two ships locked together, steel grinding against steel. And for several minutes, German submariners climbed from their conning tower onto the deck of the American ship.
Buckley’s crew fought them off with rifles, pistols, hand grenades, and according to the after-action report, a thrown coffee mug. U-66 broke free, circled once and sank. Her captain and most of her crew went down with her. The boat that had escaped Salinger’s attack on August 7th had been found again by another escort carrier in another stretch of ocean that was supposed to be empty. There was nowhere left to hide.
That same spring, Admiral Dönitz sent 15 U-boats toward the Normandy beaches on the 6th of June, 1944. Eight had no snorkel, the breathing device that allowed a submarine to run her diesels while submerged. The war diary entry for that day is one sentence. For those boats without snorkel, it reads, “This means the last operation.
” 10 of the 15 were sunk within 3 weeks. On the 5th of July, Allied hunter-killer groups were authorized to roam the western approaches and Bay of Biscay freely. The U-boats’ own waters became a killing ground. Dönitz never stopped sending men to sea. New boats left Norwegian ports in 1945, crewed by conscripts, carrying experimental equipment that had not been tested, sailing toward an Atlantic that was no longer an ocean, but a cemetery.
When Germany surrendered on May 7th, 1945, the surviving U-boat captains received a single coded signal, “Regenbogen”, “rainbow”, the order to scuttle. Over 200 submarines sank themselves in harbors and fjords rather than surrender. The men who had once hunted in wolf packs chose to drown their own boats in silence.
By then, the man who had turned escort carriers into submarine killers was already dead. Captain Arnold Isbell never received the fleet carrier command he had earned. On March 19th, 1945, he was aboard USS Franklin as a passenger en route to take command when a Japanese bomb struck the ship off Okinawa.
Isbell was among the more than 800 killed. He was 45 years old. The The the Navy named after him, USS Arnold J. Isbell, was commissioned as a hunter-killer ship. Daniel Gallery retired as a rear admiral. He wrote books about the capture of U-505 and spent years campaigning to save the submarine from the scrapyard. He succeeded.
The boat he captured sits in Chicago to this day. Karl Dönitz stood trial at Nuremberg. When asked to explain the collapse of his submarine force, he spoke carefully, as a man does when he is describing the death of something he built with his own hands. “The airplane,” he told the court, “the surprise by airplane and the equipment of the planes with radar, which in my opinion is, next to the atomic bomb, the decisive war-winning invention of the Anglo-Americans, brought about the collapse of U-boat warfare.
” He served 10 years in Spandau Prison. He was released in 1956. He never spoke publicly about his son, Peter. Here is what the German submariners wrote. They wrote that the sky had become the enemy. They wrote that they could no longer surface to charge batteries without being found within the hour. They wrote that aircraft appeared from directions where no airfield existed, over water where no carrier should be.
They wrote that something followed them underwater, something they could not hear, could not see, could not evade. They wrote that the men who left on patrol did not return and that the men who replaced them were younger and more frightened and less trained. They wrote that the iron coffin was no longer a joke. What they were describing, in the language of men who did not yet know they had lost, was the sound of an industrial democracy that had decided to solve a military problem the way it solved every other problem, by building something ordinary,
building it fast, building it in numbers that no one believed possible, and handing it to 24-year-old pilots who had learned to land on a cargo ship in a North Atlantic storm. The escort carriers did not win the Battle of the Atlantic alone, but they broke its back. And the men who sailed them on flight decks so narrow that one gust could send a plane into the sea, did it in ships that the Navy itself called combustible, vulnerable, and expendable.
The Germans called them something else. They called them the reason the ocean was no longer theirs. Thank you for watching this all the way through. If this story meant something to you, I’d be grateful if you would hit that like button. It’s how the algorithm knows to show this kind of history to people who care about it.
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