Payback: How the Royal Navy Hunted Down Hitler’s U-Boats

Payback: How the Royal Navy Hunted Down Hitler’s U-Boats

United States antisubmarine aircraft played an unsung but vital role in this campaign.

Into this hazardous operational environment entered a new group of aviators when on August 17 the first PB4Y-1 Liberators of U.S. Navy Bomber Squadron 103 (VB-103) touched down at St. Eval. After several weeks spent familiarizing themselves with Coastal Command procedures, the Navy crews moved to Dunkeswell where they relieved the soon-to-be disbanded USAAF sub-hunter squadrons. By September 5, the PB4Y-1s of VB-105 began arriving, with VB-110 closing on the United Kingdom starting on September 24.

They were commanded by Captain (later Commodore) William Hamilton of Fleet Air Wing Seven (FAW-7), who located his headquarters in nearby Plymouth. The Navy commenced operations on August 30, and by November 1 had taken over all patrol duties from the Army. Most USAAF antisubmarine crews received new combat assignments with the Eighth Air Force while their specialized B-24s were repossessed by Navy flying squadrons.

Although experienced at overwater navigation from previous assignments, these naval aviators soon discovered the Bay of Biscay held many unique perils. On September 2, skulking Ju-88s shot down a Liberator commanded by Lieutenant Kenneth Wickstrom; no aircrew survived. Two days later, a dozen German fighters mauled Lieutenant James Alexander’s PB4Y-1 off the Iberian Peninsula. Alexander somehow managed to ditch his bullet-ridden plane, enabling the 11 men aboard to escape into rubber dinghies. Rescued by Spanish fishermen some 36 hours later, they eventually returned to duty.

The Naval Technology War

There were few U-boats left for FAW-7’s flight crews to hunt. Husbanding most of its submarines for the coming cross-Channel invasion, the Kriegsmarine started to fit them with a revolutionary new defensive technology. The Schnorkel (German slang for “nose”) allowed a U-boat to operate submerged while still taking in air from above, thus theoretically eliminating the need for it to surface altogether. Allied commanders worried how their hundreds of aircraft and thousands of aviators would find submarines no longer visible on ASV radar systems.

Navy sub hunters also introduced some new weaponry to the Bay Patrol. Their Liberators now carried sonobuoys, air-delivered sonar transmitters able to detect U-boats moving under water. Once the sub’s location was marked, PB4Y-1 crews could then drop a Zombie, also known as the Mk 24 acoustic homing torpedo, on their unsuspecting prey.

Furthermore, the “MADCATS” of VP-63 operated their Magnetic Anomaly Detector-equipped PBY Catalinas over the Biscayan gulf for a time. Airmen used this apparatus to identify the gravitational disturbance caused by a submerged metal object like a U-boat and then dropped depth charges on the contact. Their PBYs proved easy pickings for Luftwaffe fighters, though, and the MADCATS soon moved to the Mediterranean’s calmer waters where their specialized gear worked more effectively.

The Fate of the Calvert n’ Coke

Liberators of FAW-7 joined Commonwealth aircraft in an all-day encounter with U-996 on November 10. Caught on the surface by two Wellington bombers, this resilient U-boat then withstood attacks by three U.S. Navy PB4Y-1s before a Czech-manned Liberator disabled it with rocket fire. Unable to dive, U-996’s crew finally scuttled its sub two miles off the Spanish coast.

As mentioned previously, the last flight of Calvert n’ Coke took place on November 12, 1943, when that VB-103 Liberator failed to return from a night patrol mission. Naval officials listed all 10 members of Lieutenant Ralph Brownell’s crew as missing in action but did not solve the mystery of their unexplained disappearance until after the war ended. Investigators examining captured German war diaries discovered the airmen had, in fact, sunk U-508 on that lonely patch of ocean before meeting their doom.

In December, all three patrol squadrons took part in an unusual battle against German surface ships, catching the blockade runners Osorno and Alsterufer as they traversed the bay bound for Asian waters. Heavily escorted by German destroyers, the two raiders traded blows with Coastal Command aircraft for three days starting on Christmas Eve 1943. Punished by relentless depth charge, bomb, machine-gun, and rocket attacks from dozens of Allied warplanes, neither vessel made it to port. One VB-110 PB4Y-1, commanded by Lieutenant W. Parish, was shot down while making a low-level strike against the Alsterufer on December 26.

These moments of excitement notwithstanding, most missions over the bay passed uneventfully. “The chief enemy of the patrol plane pilot is boredom,” recalled VB-105’s Owen Windall. “Boredom begets inattention, then indifference. Hundreds of hours are spent at sea with nothing to look at but an endless expanse of waves and sky.” Other hazards included miserable winter weather, which contributed to the loss of several FAW-7 Liberators. Most of all, crewmen feared ice—if enough of it accumulated on the wings of their heavily loaded PB4Y-1s they would fall out of the sky without warning.

Operation Cork: Sealing Off the English Channel For D-Day

The first American U-boat kill utilizing Zombie munitions occurred on January 28, 1944, when a VB-103 Liberator nicknamed The Bloody Miracle caught U-271 on the surface west of Ireland. Lieutenant George Enloe and crew put six depth charges across the sub’s beam and followed up with a lethal homing torpedo after they observed the vessel crash dive beneath them. Strike photos revealed first evidence of a Schnorkel, troubling news for the Allies then preparing to invade Normandy.

For D-Day, Coastal Command, now led by RAF Air Chief Marshal Sholto Douglas, planned to seal off all approaches to the English Channel with saturation air patrols. The aptly named Operation Cork would, if successful, prevent Dönitz’ U-boats from getting anywhere near the Allied fleet by creating an “unclimbable fence” of air antisubmarine forces for them to face.

Reinforced for Normandy with 25 squadrons, No. 19 Group began flying Cork missions on June 5. Navy Liberators, temporarily augmented by detachments from Gibraltar-based VB-114, were assigned to patrol a region off the Cherbourg Peninsula. The pace was intense. Directed to cover individual sectors of ocean twice an hour, each squadron generated seven missions per day compared to two or three flown previously.

Forty-three of Admiral Dönitz’ Biscay-based U-boats sortied against the invasion fleet in the weeks following D-Day. They failed miserably. By June 23, Coastal Command planes had killed nine U-boats and damaged 11 more.  Unable to move without being detected, the surviving non-Schnorkel-equipped submarines could only cower helplessly on the ocean floor. Just five vessels fitted with this new breathing device managed to make it past the escort screen, torpedoing three warships and five freighters before being driven off by British destroyers.

The Successful but Costly Bay Offensive

Thanks to Coastal Command, Allied forces were largely free to cross the English Channel without fear of U-boat attacks. In August, what remained of Germany’s submarine fleet in France transited the Bay of Biscay one final time as American ground troops approached their bases. The three-year Bay Offensive concluded victoriously for the Allies.

This triumph came with a heavy cost. During their time in England, USAAF antisubmarine squadrons lost 12 planes and 102 men due to enemy action, accidents, or causes unknown. Navy patrol bomber losses over the bay amounted to 16 aircraft and 157 crewmen. In return, American sub hunters received credit for sinking 13 U-boats from February 1943 to the end of Biscayan operations 18 months later.

United States antisubmarine aircraft played an unsung but vital role in this campaign. American technology and manufacturing capacity, including long-range Liberator bombers and the Zombie acoustic homing torpedo, contributed a significant amount of striking power to the Bay Patrol. Yet victory was ultimately measured by the determination, fighting spirit, and sacrifice demonstrated by thousands of Allied airmen. These aviators proved themselves to be the deciding factor in this deadly cat-and-mouse game fought between Coastal Command and German U-boats in the Bay of Biscay.

This article originally appeared on the Warfare History Network. Originally Published December 15, 2018.

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