Hunter-Killer: The Capture of U-505
Prologue: The Atlantic Graveyard
At 11:15 on the morning of April 9th, 1944, Lieutenant Commander George Castleman stood on the bridge of USS Pillsbury, his eyes fixed on the horizon. The Atlantic was restless, a gray expanse of waves and wind, haunted by the ghosts of lost ships. Ten months commanding a destroyer escort, dozens of depth charge attacks, zero captures. But today, something was different.
A German submarine had broken the surface seven hundred yards off Pillsbury’s starboard bow. The U-boat was U-515, commanded by Kapitänleutnant Werner Hanke—one of Germany’s deadliest submarine aces. Hanke had sent twenty-five Allied ships to the bottom, including the British troop ship Ceramic, where over six hundred men, women, and children had drowned in a single night. Now, after hours of relentless depth charging from Pillsbury and her sister ships, Hanke’s boat was crippled, forced to the surface.
The German crew scrambled onto the deck. Some manned their guns, others jumped into the Atlantic. Castleman’s ship opened fire. So did USS Flaherty. Machine guns raked the submarine’s conning tower. Rockets streaked across the water from aircraft circling overhead. Within minutes, U-515’s bow lifted toward the sky. She slid backward into the Atlantic and disappeared.
Forty-four German sailors were pulled from the water, including Hanke himself. The task group had destroyed one of Germany’s most successful U-boats. By every measure, it was a victory. But Captain Daniel Gallery, commanding the escort carrier USS Guadalcanal and the entire Hunter-Killer Group, saw something else entirely. He saw a missed opportunity.
Chapter 1: The Missed Prize
Gallery had watched U-515 float on the surface for nearly ten minutes before she sank. Ten minutes. In that time, his ships had done exactly what the Navy had trained them to do—they had destroyed the enemy. But Gallery realized that if he had been ready, if he had trained boarding parties in advance, he might have captured the submarine instead.
The intelligence value would have been extraordinary: German code books, Enigma cipher machines, torpedo guidance systems, acoustic homing technology. The Allies had been trying to crack German naval codes for years. A captured U-boat could hand them everything.
No American warship had boarded and captured an enemy vessel at sea since 1815—the War of 1812, one hundred twenty-nine years. The Navy did not train sailors for boarding actions. There were no procedures, no protocols. No one had even considered it possible.
Gallery decided to change that.
Chapter 2: Preparing for the Impossible
The problem was immense. German U-boat crews were trained to scuttle their boats within minutes of surfacing. They opened sea valves. They set demolition charges. They destroyed code books and smashed equipment. Even if American sailors could reach a surfaced submarine, they would be boarding a sinking ship rigged with explosives. The Germans would rather die than let their secrets fall into Allied hands.
Statistics were brutal. In 1943 alone, German submarines had sunk over three hundred Allied merchant ships. American destroyer escorts hunting faced a simple equation: find the submarine, destroy it before it destroys you. There was no time for boarding parties, no margin for error. Every second a U-boat remained afloat was another second it could fire torpedoes.
Pillsbury was an Edsall-class destroyer escort, twelve hundred tons, three-inch guns, depth charges, and hedgehog mortars. She was built to hunt and kill submarines, not to capture them. But Gallery had given the order. Every ship in Task Group 22.3 would form a boarding party. They would train. They would prepare. And on their next patrol, they would try something the United States Navy had not attempted in over a century.
Castleman assembled his best men. He told them they were going to board a German submarine. They had six weeks to figure out how.
On May 15th, 1944, Pillsbury sailed from Norfolk with a new mission. The official order said routine anti-submarine patrol. But Gallery had received secret authorization from the highest levels of naval command: bring one back alive.
The boarding party from Pillsbury consisted of eight men. Lieutenant Junior Grade Albert David would lead them. He was forty-one years old, a former enlisted sailor who had worked his way up through the ranks over twenty-five years in the Navy. He served as the ship’s assistant engineering officer. He knew machinery. He knew pipes and valves and how ships stayed afloat. David had never boarded an enemy vessel. No one in the United States Navy had, not in living memory.
Training began immediately after Pillsbury left Norfolk. Every day, David drilled his men on the fantail. They practiced climbing over railings. They rehearsed jumping from a whaleboat onto a moving deck. They memorized the general layout of a German Type IX submarine, based on intelligence photographs and technical drawings.
The challenges were staggering. A surfaced U-boat would be circling erratically, its rudder likely jammed by depth charge damage. The deck would be slick with seawater and fuel oil. German sailors might still be aboard, armed and desperate. The submarine could dive at any moment, taking the boarding party down with it. And then there were the explosives. German commanders followed strict protocols for scuttling. The moment a U-boat surfaced under attack, the captain would order demolition charges armed. These were placed throughout the submarine, designed to detonate and send the boat to the bottom within minutes. The crew would also open sea valves, flooding the engine room and control spaces.
Even if American sailors reached the submarine, they would be entering a vessel that was simultaneously sinking and rigged to explode. David’s team had to work fast. They estimated three to five minutes from boarding to catastrophic flooding. In that window, they needed to locate and disarm demolition charges, find and close sea valves, and stop whatever other scuttling measures the Germans had initiated—all while navigating the cramped, unfamiliar interior of a foreign submarine in near darkness.
The tools were basic: wrenches, flashlights, sidearms. There was no specialized equipment for capturing enemy submarines because no one had ever needed any.
Gallery held conferences with his destroyer escort captains throughout the three-week voyage. Commander Frederick Hall coordinated the tactical approach. The plan called for careful use of weapons once a U-boat surfaced. Ships would fire small caliber guns only, enough to drive the German crew overboard, but not enough to sink the submarine. Aircraft would strafe the decks to prevent the enemy from manning their guns, but pilots were ordered to avoid hits below the waterline. The goal was to wound the submarine, not kill it.
Pillsbury’s role was critical. She would be the first ship to lower a boarding party. Castleman positioned his whaleboat crews for rapid deployment. The moment a U-boat broke the surface, David and his men would be over the side and racing toward it.
There was no guarantee the plan would work. The Navy had never attempted anything like this. Intelligence suggested that German crews could complete scuttling procedures in under four minutes. If David’s team was even thirty seconds too slow, they would go down with the submarine.
Chapter 3: Contact in the Atlantic
The days passed in tense anticipation. Pillsbury and her task group patrolled the shipping lanes west of Africa, searching for any sign of German U-boats. Aircraft from Guadalcanal flew constant patrols, scanning the waves for periscopes and snorkel masts. The men grew restless. David continued drilling his boarding party, but the repetition wore on them. They had memorized every procedure. They had rehearsed every scenario. Now they simply waited.
On the morning of June 4th, 1944, the Atlantic was calm, the sky a pale blue. Gallery had ordered a course change to head for Casablanca to refuel. The patrol seemed finished—until 11:09, when the sonar operator aboard USS Chatelain reported a contact: bearing 045, range 800 yards. A submarine was running submerged directly toward the carrier Guadalcanal.
David’s team had trained for six weeks. Now they had minutes.
Chatelain turned hard to starboard and accelerated toward the contact. Two FM2 Wildcat fighters from Guadalcanal dove toward the sea, their pilots spotting the dark shape of a submarine running just below the surface. They opened fire with their machine guns, stitching lines of spray across the water to mark the position for the destroyers below.
At 11:16, Chatelain released her first pattern of depth charges. The explosions sent white columns of water erupting skyward. Oil bubbled to the surface. The submarine was hit.
Six and a half minutes after the first attack, the U-boat broke the surface 700 yards from Chatelain. She came up bow first, her gray hull streaming seawater, her conning tower scarred with rust. The depth charges had jammed her rudder. Her lights were out. Seawater poured through cracked pipes in her engine room. The submarine began circling to starboard at five or six knots, unable to steer.
German sailors scrambled through the hatches onto the deck. Some tried to reach their deck guns. Chatelain and the other escorts opened fire with everything that would bear. Machine gun rounds sparked off the conning tower. A German sailor fell dead on the deck. The rest threw up their hands and began jumping into the Atlantic.
On Pillsbury’s bridge, Castleman watched the submarine spiral through the water. This was the moment. He gave the order to lower the whaleboat.
David and his eight-man team were already waiting. They dropped into the boat and cast off, the coxswain steering directly into the submarine’s circling path. The U-boat was still moving, still turning. They would have to intercept it like chasing a wounded animal.
The whaleboat cut inside the submarine’s arc. The men could see the gray hull looming larger with each second. Oil slicked the water around them. German sailors thrashed in the waves nearby, shouting and waving for rescue. David ignored them. His focus was the submarine.
The whaleboat pulled alongside. The hull was slick with oil and seawater. David grabbed a railing and pulled himself onto the deck. His men followed. The submarine rolled beneath their feet—still circling, still sinking by the stern. One German body lay face down near the conning tower hatch. No other enemy sailors were visible.
David did not hesitate. He climbed through the hatch and dropped into the control room. The interior was nearly dark. Emergency lighting cast red shadows across unfamiliar machinery. Water sprayed from broken pipes. The deck was tilted at an angle. The submarine was flooding. David could hear the rush of seawater somewhere below. The Germans had opened the sea valves before abandoning ship. He had minutes, maybe less, before the boat went down.
His men spread through the compartments. One found the sea strainer valve, a large pipe allowing ocean water to flood the bilge. The cover had been removed and thrown aside. He located it nearby and screwed it back into place. The flooding slowed.
Others searched for demolition charges. They found thirteen throughout the submarine, placed in the engine room, the torpedo compartments, the control spaces. Each one had to be located, examined, and disarmed. The charges had timers. Some were set to detonate within minutes. David’s team worked in near darkness, crawling through oily water, tracing unfamiliar pipes and cables. They pulled wires. They removed detonators. They sealed valves and hatches.
The submarine continued to settle by the stern, her aft deck already submerged. Above them, the circling submarine posed a new danger. Without steering, the U-boat swung toward Pillsbury herself. Castleman had to maneuver his ship to avoid collision. The whaleboat that had delivered David’s team was crushed between the two hulls. Three of Pillsbury’s compartments flooded from the impact, but the boarding party stayed aboard the submarine. They had stopped the scuttling. The U-boat was wounded, but she was not sinking.
At 11:30, a second boarding party arrived from Guadalcanal, led by Commander Earl Trosino, the carrier’s chief engineer. He found David’s men still working in the flooded compartments, still pulling demolition charges from hidden corners. They had captured a German submarine. Now they had to keep her afloat.
Chapter 4: Salvage and Secret Intelligence
Commander Trosino crawled through the flooded compartments for hours. He was a merchant marine engineer before the war, experienced with ship systems and machinery, but he had never been inside a German submarine. No American had. The Type IX U-boat was larger than he expected—over 250 feet long, eleven compartments connected by watertight hatches. The design was foreign, the labels in German, the equipment unfamiliar.
Trosino traced pipelines by hand, following them through the oily bilge water until he understood how the submarine’s systems connected. The stern was already underwater. The depth charge damage had cracked pipes and ruptured tanks throughout the aft section. Seawater continued to seep in through dozens of small leaks. If they could not stop the flooding, the submarine would sink within hours.
Trosino organized the salvage effort. He directed men to specific valves. He identified which pumps still functioned. He jury-rigged connections between compartments to redirect the flow of water. Slowly, the flooding stabilized.
While Trosino worked on keeping the submarine afloat, David’s team collected intelligence materials. They found two Enigma cipher machines intact, complete with their coding rotors. They gathered stacks of code books, signal documents, and operational orders. They located charts showing U-boat patrol zones across the Atlantic—900 pounds of classified German naval documents. The haul was extraordinary.
Allied codebreakers at Bletchley Park in Britain had been working to crack German naval communications for years. They had achieved partial success, but the Germans regularly changed their cipher settings. Fresh code books and an intact Enigma machine could unlock months of intercepted messages.
But there was more. In the forward torpedo room, the salvage teams found two acoustic homing torpedoes—the Germans called them Zaunkönig. The Allies had heard rumors of these weapons, but had never examined one. The torpedoes used sound to track their targets, homing in on the propeller noise of Allied ships. Understanding how they worked could save hundreds of lives.
Chapter 5: The Secret Journey
With the submarine stabilized and the intelligence haul secured, Captain Gallery faced a new challenge. His task group was now responsible for a crippled enemy submarine, 150 miles off the African coast, with 3,000 American sailors as witnesses. If the Germans learned that U-505 had been captured intact, they would change their codes immediately. Every advantage gained from the captured materials would vanish. The entire operation would be worthless.
Gallery ordered absolute secrecy. No radio transmissions about the capture. No written records in ship logs. The German prisoners—58 men, including their wounded captain—were confined below decks on Guadalcanal, forbidden from speaking with anyone. Then Gallery received new orders from Washington. The original plan had been to tow the submarine to Casablanca. Now he was directed to take her to Bermuda instead—2,500 miles across the open Atlantic.
Timing was critical. Allied forces were about to invade Normandy. D-Day was scheduled for June 5th, pushed to June 6th due to weather. If German intelligence discovered that their codes had been compromised days before the largest amphibious invasion in history, the consequences could be catastrophic.
Pillsbury attempted to take the submarine under tow, but the collision during the capture had damaged her hull. Three compartments were flooded. She could not maintain the strain. Guadalcanal herself rigged a tow line from the carrier to the U-boat and began the slow journey north. The voyage took 15 days. Storms threatened to swamp the waterlogged submarine. Salvage crews remained aboard around the clock, pumping water and monitoring leaks. The fleet tug USS Abnaki eventually took over towing duties, but the danger never lessened.
On June 19th, the task group entered Port Royal Bay, Bermuda. The U-boat was immediately hidden in a remote corner of the naval base. She was repainted to disguise her German origins and given a new designation, USS Nemo. The 58 German prisoners were transferred to a secret camp in Louisiana. The Red Cross was denied access. Their families in Germany received notifications that they were missing, presumed dead. They would not learn the truth until 1947.
Admiral Ernest King, commander-in-chief of the United States Fleet, reviewed the intelligence haul. The code books alone were invaluable. But King had another concern. Gallery had taken an enormous risk. If the capture had failed, if the Germans had learned their codes were compromised, the damage to Allied operations could have been incalculable. The admiral’s response was measured. Gallery would receive the Legion of Merit, but he would also receive a private warning. The secrecy had to hold. If it did not, there would be consequences.
The German Navy never learned what happened to U-505. Admiral Karl Dönitz, commander of the U-boat fleet, received the final transmission from the submarine on June 3rd. She reported her position off the African coast and indicated she was returning to base in Lorient, France. After June 4th, silence. This was not unusual. U-boats disappeared constantly in 1944. Allied hunter-killer groups and long-range aircraft had turned the Atlantic into a killing ground for German submarines. Dönitz assumed U-505 had been sunk by depth charges or aerial attack like hundreds of others before her. He ordered no changes to German codes. He issued no warnings about compromised communications. The navy continued using the same Enigma settings, the same cipher procedures, the same operational protocols.
The secrecy held. Three thousand American sailors who had witnessed the capture said nothing. They wrote no letters home describing what they had seen. They made no mentions in personal diaries. Captain Gallery had explained the stakes during the voyage to Bermuda. If word reached the Germans, the intelligence value would be destroyed. Allied sailors and soldiers would die because of loose talk. The men understood. Not a single breach occurred.
Chapter 6: Turning the Tide
At Bletchley Park in England, British codebreakers received the captured materials within weeks. The Enigma machine and its rotors confirmed their understanding of German cipher methods. The code books provided settings valid through the summer of 1944. Intercepted U-boat transmissions that had been gibberish suddenly became readable.
The intelligence revealed German submarine positions across the Atlantic. It exposed patrol patterns and attack strategies. It identified supply routes and rendezvous points. Allied convoy commanders adjusted their courses to avoid known U-boat concentrations. Hunter-killer groups received precise coordinates for their targets.
The acoustic homing torpedoes proved equally valuable. American engineers at the Naval Ordnance Laboratory in Washington disassembled the Zaunkönig weapons and analyzed every component. They discovered the torpedoes tracked the cavitation noise created by ship propellers. Within months, the Navy developed countermeasures. Ships began towing noisemakers called “foxers,” decoys that produced louder cavitation sounds than the ships themselves. The torpedoes chased the decoys instead of their intended targets.
German U-boat commanders noticed the change. Their acoustic torpedoes, which had been devastating Allied escorts, suddenly missed with alarming frequency. They reported the failures to headquarters. Dönitz suspected the Allies had developed some form of countermeasure, but he never connected it to U-505. He assumed the technology had been captured from a torpedo that failed to detonate, not from a submarine taken intact.
The Battle of the Atlantic, which had threatened to strangle Britain’s supply lines for four years, was effectively won.
Chapter 7: Legacy and Memory
Pillsbury returned to operations after repairs in Norfolk. The collision with U-505 had damaged three compartments, but the shipyard crews restored her within weeks. By late summer, she was back on patrol with Task Group 22.3. The Hunter-Killer Group continued sweeping the Atlantic through the fall. They found no submarines. German U-boat activity had collapsed in the central ocean. The few boats still operating hugged the European coastline or lurked in distant waters where Allied air cover was thin.
The war in Europe approached its end. By April 1945, Allied armies had crossed the Rhine and were driving into Germany. The Soviet forces closed on Berlin from the east. Hitler’s Reich was collapsing, but the U-boat war was not finished.
German Naval Command had one final operation planned. A group of submarines equipped with the latest technology would cross the Atlantic and strike the American coast. The mission was desperate, a last attempt to prove that Germany could still threaten the enemy homeland.
Operation Teardrop was born from fear. Allied intelligence had detected a group of German submarines heading west across the Atlantic in early April 1945. The boats were Type IX long-range submarines capable of reaching the American coastline. What alarmed naval planners was the cargo they might be carrying. Rumors had circulated for months about German plans to launch V-1 flying bombs or V-2 rockets from submarine platforms. The weapons had devastated London. A single V-2 striking New York or Washington could kill thousands.
For two weeks, the task group patrolled in shifting fog and heavy seas. Aircraft flew constant searches. Sonar operators listened for contacts. The submarines were out there somewhere, running silent beneath the gray swells.
On April 24th, USS Frederick C. Davis was hit and sunk by U-546, the last American warship lost in the Atlantic. Pillsbury and seven other destroyer escorts hunted U-546 for ten hours, finally forcing her to the surface. Thirty-three survivors were pulled from the water, including her captain. The Navy interrogated him for days, desperate to learn if any secret weapons were aboard. The answer was no. The mission was a final conventional attack, a desperate gesture by a dying navy.
By May 8th, 1945, Germany surrendered. Pillsbury was present for the surrender of U-858, escorting her to Cape May, New Jersey. In thirteen months of combat operations, Pillsbury had participated in the destruction of two German submarines and the capture of a third. No other American warship could claim such a record.
Epilogue: The Ship That Endures
U-505 was the only German submarine captured by American forces during the entire war. The intelligence materials recovered from her hull provided months of insight into German naval operations. The Enigma machine and code books allowed Allied cryptographers to read enemy communications during the critical summer of 1944 when the Normandy invasion hung in the balance.
Task Group 22.3 received the Presidential Unit Citation for the capture of U-505. Lieutenant Albert David received the Medal of Honor for leading the boarding party onto the circling submarine—risking his life above and beyond the call of duty. It was the only Medal of Honor awarded to a Navy sailor in the entire Atlantic theater of World War II.
After the war, the Navy had no further use for the submarine. Plans were made to tow her out to sea and sink her with gunfire. But Gallery had other ideas. He launched a campaign to save U-505, contacting civic leaders in Chicago, his hometown. The Museum of Science and Industry agreed to host the exhibit. In 1954, engineers floated U-505 down the Atlantic coast, through the Gulf of Mexico, and up the Mississippi River system to Chicago. The final leg required hauling the submarine across city streets on specially constructed rollers.
On September 25th, 1954, Fleet Admiral William Halsey dedicated U-505 as a permanent war memorial. She was placed outdoors on the museum grounds where visitors could climb aboard and walk through the same compartments that Albert David and his men had entered a decade earlier.
David himself never saw the memorial. He died of a heart attack on September 17th, 1945, three weeks before he was scheduled to receive the Medal of Honor. President Harry Truman presented the medal to his widow, Linda May David, at a White House ceremony the following month.
Pillsbury herself served until 1947 when she was decommissioned and placed in reserve. The Navy brought her back in 1955, converted to a radar picket ship for Cold War duty along the Atlantic barrier. She patrolled for Soviet submarines until 1960, then was decommissioned a final time.
No monument marks her service. No museum displays her artifacts. The ship that participated in the only submarine capture by American forces since 1815 exists now only in photographs and official records.
But U-505 endures. In 2004, the Museum of Science and Industry completed a major renovation. The submarine was moved indoors to a climate-controlled underground exhibit hall. Visitors can now tour her interior, preserved almost exactly as she appeared when David’s men came through the conning tower hatch. The Medal of Honor that David never lived to receive is displayed alongside the submarine. So are the Enigma machines his team recovered, the code books that unlocked German communications, the acoustic torpedoes that revealed enemy secrets.
Over 30 million people have visited the exhibit since 1954. They walk through the control room where David searched for demolition charges. They see the valve that Trosino closed to stop the flooding. They stand in the compartments where eight American sailors saved a sinking enemy vessel through courage and determination.
The capture of U-505 remains the only time the United States Navy boarded and seized an enemy warship at sea since the War of 1812. It has never happened again.
