Exercise Tiger — Kriegsmarine Attack at Slapton Sands By: Tom Laemlein

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The more I think I know something about Operation Overlord and Operation Neptune, the famed Normandy landings of World War II, the more I realize that I have only scratched the surface in understanding the most complex operation in military history.

German E-boat attacking Allied LST during Exercise Tiger — This artwork was made on a postcard by Nazi Germany authorities during World War II to inspire confidence in the country's military and navy. The torpedo boats inflicted many casualties on the United States Army, United States Navy and United States Coast Guard during the training for Operation Neptune — the Normandy landings.
Kriegsmarine postcard of a slashing, high-speed torpedo attack by Schnellboat (aka S-boot or E-boat.) They were a deadly wrinkle in Exercise Tiger. Image: Author’s collection

The incredible effort that went into the preparations for the D-Day landings is staggering. The monumental logistics required to put the men and equipment on a hostile beach in France are often overlooked.

DUKW simulated fire Slapton Sands May 1944 — These soldiers train for amphibious warfare during Exercise Tiger. The training was for the Normandy landings and were protected by only one destroyer when German E-boats hit the convoy of ships.
A DUKW amphibious truck and its soldiers come under simulated fire on the beach during Exercise Tiger. Image: NARA

On the morning of April 28, 1944, as the ships of Convoy T-4 prepared to participate in “Exercise Tiger”, a large-scale rehearsal for D-Day, the fog of war settled in, and real-life events conspired to make the practice into a brutal introduction to the realities of the war.

After the war, captured German documents revealed that Luftwaffe and Kriegsmarine reconnaissance had identified a large group of Allied ships, including capital ships and many troop transports, gathering at the harbors of Portsmouth, Pagham, Chichester, Langstone and Exbury. Around Southampton, German intelligence identified hundreds of trucks and other military vehicles, and German radio intercepts indicated that a large operation was underway.

US Coast Guard assists United States of America soldiers onto landing boats during invasion training During Exercise Tiger, an Allied live-fire rehearsal for the Normandy landings, tragedy struck in Lyme Bay when a convoy of landing ships was ambushed by German E-boats. Poor radio frequency coordination left the convoy vulnerable to attack, resulting in significant loss of life. The event underscored the dangers of amphibious warfare during World War II.
Men of the U.S. Coast Guard help soldiers over side and into the landing craft for a invasion exercise near Slapton Sands. Image: NARA

What the Germans found by April 25, 1944, were the preparations for Exercise Tiger, a massive invasion rehearsal that would see several convoys of ships operating in the waters of Lyme Bay — the “rehearsal beaches” on the coast were chosen for their similarity to the targeted invasion beaches in Normandy.

transport ship loaded with trucks during Exercise Tiger The sailors and soldiers lost during Exercise Tiger are honored at sites like Brookwood Cemetery in Surrey. Many succumbed to hypothermia or injuries after their ships were torpedoed by German U-boats in the English Channel. Their sacrifice paved the way for the success of Operation Overlord.
For full realism in Exercise Tiger, the vehicles loaded on the transport ships were fully fueled. This would only add to the carnage when the German E-boats struck. Image: NARA

The war history of the U.S. 5th Engineer Special Brigade provided this description of the Americans’ temporary home and training grounds for their “friendly invasion” of England:

“Thousands of Yanks know this part of Devon, chosen because of its resemblance to the Cherbourg coast, almost as well as their own hometown. The area comprises the villages of Strete, on the brow of a 350-foot cliff, and Slapton, just 50 feet above sea level — these two bore the brunt of the constant assaults. Almost all the windows in the villages were broken, although the blasts played their usual tricks, and some glass porches and hot houses remained intact next to shattered houses.” 

On April 24, 1944, eight LSTs (Landing Ship, Tanks) gathered to form Convoy T-4, and they slowly approached Lyme Bay. On board the massive transport ships, the tanks and wheeled vehicles were filled with fuel and ammunition to provide realistic conditions for the invasion exercise.

Higgins Boats approach shore during Exercise Tiger A Landing Ship, Tank, participating in Exercise Tiger suffered devastating damage when a Nazi Germany E-boat attack unleashed deadly torpedoes. The stern of the ship was blown apart, leaving survivors clinging to personal flotation devices in the frigid waters of the English Channel. These training tragedies revealed critical flaws in convoy protection and communication protocols.
Just off the shores of Slapton Sands, the Higgins boats begin their runs to the beach during Exercise Tiger. Image: NARA

On the 25th, as the LSTs were entering Lyme Bay, they were spotted by German recon aircraft — and their photos showed German intel officers the significant build-up of ships, military vehicles and men at Portsmouth, Spithead, Southampton, as well as Pagham, Chichester, Langstone, and Exbury. The Germans also intercepted enough radio transmissions to confirm that something significant was going on in the area.

Convoy T-4 started off with only two escorts — the destroyers HMS Scimitar and HMS Azalea. Unfortunately, the escorts were quickly reduced by half as the Scimitar collided with an American LST outside Portsmouth. It took some time for HMS Saladin to steam out to replace her, and did not arrive in time to protect the convoy.

landing craft deliver troops to beach Exercise Tiger HMS Onslow (G17), a Royal Navy destroyer, sounded general quarters during Exercise Tiger as it rushed to protect the convoy under E-boat assault. Despite the destroyer’s swift maneuvers, the attack inflicted severe losses on Allied forces. The chaos highlighted the unforgiving nature of the Battle of the Atlantic.
Massive landing crafts deliver vehicles to the beach during Exercise Tiger in 1944. Image: NARA

While the escorts and the American transport ships had been briefed on a potential E-boat (German torpedo boats) threat, the individual ship commanders were particularly sensitive to the secret nature of the training operation. There were several men aboard the convoy who knew the timing and plans for Operation Overlord.

The German torpedo boats were actually spotted in the overnight hours as they approached the bay and British radar picked them up. The E-boats were also spotted at a distance by lookouts on the LSTs. Nothing was done.

A little later, British coastal gun crews spotted the German boats but held their fire. The destroyer Azalea was told, but did nothing. An overabundance of caution, focused on radio silence, was exacerbated by the use of incorrect radio frequencies between U.S. Navy and Royal Navy ships.

By 1:30, the S-Boots began their attack, firing their automatic cannons and launching torpedoes.

German S-boat makes attack run Amphibious vehicles and Willys MB jeeps were deployed during the live-fire exercises at Slapton Sands, Devon, as part of Exercise Tiger. The terrain simulated Utah Beach, preparing troops for the challenges of combat in Normandy. This meticulous preparation came at a high cost, as the exercise turned into a somber reminder of war’s unpredictability.
The German E-boats could reach up to 48 knots during attack runs. The E-boat was a name given by the Allies, while Germany called them “S-boot” or “Schnellboot”. Image: Author’s collection

LST-507 was hit in its auxiliary engine room and quickly caught fire — the fully fueled vehicles aboard burned furiously while ammunition cases exploded. Green troops ready for amphibious training were not properly prepared to abandon a burning ship. Many were still wearing full packs and overcoats when they went into the water, and most of them quickly drowned.

About 45 minutes later, LST-531 exploded and sank within 10 minutes, with 467 men dying with her.

Shortly after, LST-489 was hit, losing her rudder and sustaining significant casualties.

Kriegsmarine S-boat in World War II M4 Sherman tanks and trucks rolled ashore in heavy gear as Exercise Tiger tested the full scope of amphibious warfare. Miscommunication during the exercise led to live ammunition tragedies, claiming the lives of many soldiers. The lessons learned were vital for improving coordination before D-Day.
Sleek and deadly, the E-boats caught the practice-invasion convoy by surprise. Author’s collection

With the water temperature at about 40 degrees, survivors struggling in the water were soon to be overcome by hypothermia.

In all, four LSTs bore the brunt during the attack. LST-289 was torpedoed and damaged, but returned to port. LST-507 was torpedoed and sunk. LST-511 was damaged by friendly fire, but returned to port. LST-531 was torpedoed and sunk.

rescue survivors Exercise Tiger The South Hams district in Devon bore witness to the aftermath of Exercise Tiger when survivors and bodies washed ashore. Local communities rallied to support the military effort, despite the secrecy surrounding the tragedy. To this day, the area honors those who trained and perished in preparation for the Normandy landings.
Hundreds of men went into the waters of Lyme Bay after the S-boot attacks. Nearly 1,000 men were killed or wounded. Many drowned or succumbed to hypothermia waiting to be rescued. Image: NARA

The cost was incredibly high, and the six boats of the 5th S-Boot Flotilla got away cleanly. The LSTs had been travelling in a straight-line formation, and the use of just a single escort conspired to make it rather easy for the German torpedo boats.

The confluence of errors and miscommunication conspired to place Convoy T-4 dramatically in harm’s way, and a level of danger not even found during the actual D-Day landings. The grisly final accounting shows that 749 U.S. soldiers and sailors lost their lives that day, and more than 200 were wounded.

With D-Day just a few weeks away, the lessons learned from the disaster at Exercise Tiger, and the proposed remedies, needed to be swiftly implemented.

LCI at Slapton Beach 1944 A convoy of landing ships zigzagged across the English Channel to avoid U-boat attacks during Exercise Tiger. Despite these maneuvers, torpedoes from German forces found their mark, leaving the convoy in disarray. Survivors recalled the devastating scenes on deck as chaos unfolded.
Infantry trudges ashore on a seemingly uncontested beach at Slapton Sands. Out in Lyme Bay, it was a very different story. Image: NARA

Communications between U.S. Navy and Royal Navy were standardized. The infantrymen headed to the beach were given more complete training in the use of lifejackets. It was a small change, but one that certainly had a positive effect on morale.

A group of light boats were also detailed to pick up survivors of sunken ships during the landings. Most importantly, there was a renewed focus on fighting off German coastal forces, particularly the deadly S-Boots.

While U-boats captured much of the attention and gained most of the headlines, Germany’s fast-attack torpedo boats, the “Schnell boats” or “S-Boots” were quietly one of the Kriegsmarine’s most effective weapons. Once the German navy gained the French ports on the English Channel, any shipping along Britain’s eastern coastline was in danger.

E-boat captured by the Royal Navy Plymouth Port bustled with activity as Exercise Tiger assembled a fleet of ships and vehicles. Soldiers loaded trucks and tanks onto landing craft, unaware of the impending tragedy. This staging area became a crucial hub for the Normandy invasion, despite the grim toll of the rehearsal.
An S-Boot damaged and captured by the Royal Navy. Note the bow-mounted 20mm Flak. Image: NARA

The existential threat from the S-Boots in the Channel led the Royal Navy to develop and maintain a significant Motor Gun Boat (MGB) force. Pitched battles between the fast-attack forces were regular events, and by the spring of 1944 the S-Boots remained a persistent threat.

During April 1943, German Admiral Donitz commented on the evolving dynamics of the Channel forces: “Against the constantly improving enemy defenses, the S-Boot can only remain effective if it continues to operate as a sufficiently large force. The development of S-Boot tactics therefore follows the same path as U-boat tactics. In the Channel, the boats are used now only in packs.”

E-boat base during World War II The Normandy American Cemetery and Memorial stands as a testament to the soldiers who fell during Exercise Tiger and Operation Overlord. Many who died in the English Channel tragedy were later interred here, alongside those lost on Utah Beach. Each grave marks a story of sacrifice in the fight against Nazi Germany.
Beginning on the night of June 14, 1944, RAF heavy bombers pounded the S-Boots Channel bases. Many boats were sunk and several irreplaceable commanders were killed. Polish National Archives

By 1944, the S-Boots carried progressively heavier armament. Many boats carried a 37mm automatic cannon (or a 40mm Bofors) in the aft positions, while a few carried a quadruple 20mm Flak 38. In the bow, a 20mm Flak was mounted in the forward turret, while various single and twin MG34s provided additional AA firepower.

The boats carried two fixed, forward firing torpedo tubes, with the pair of reload torpedoes carried on a bed of ball bearings, to be easily rolled into place. G7a torpedoes were carried throughout the war. On mining missions, the torpedoes were replaced by six mines. The diesel-engine S-Boots could sustain a speed of about 43 knots and accelerate up to 48 knots (nearly 55 mph) for short periods. Their range was excellent — up to about 850 miles.

E-boat World War II German E-boats, known as Schnellboote, were fast attack craft designed for hit-and-run tactics in coastal waters. These vessels, armed with torpedoes and capable of high speeds, proved devastating during Exercise Tiger, ambushing Allied ships under cover of darkness. Their surprise attack in Lyme Bay revealed the vulnerability of Allied convoys and underscored the ongoing threat posed by Nazi Germany's naval forces.
The S-Boots operated in the English Channel, the North Sea, the Baltic Sea, the Adriatic Sea, the Aegean Sea, the Black Sea and in the Mediterranean Sea. Image: Danish Bornholms Museum

Prior to the invasion there was often a crippling lack of cooperation between the Wehrmacht, Kriegsmarine and Luftwaffe. The Germans placed great faith in their reconnaissance ability, but no one seemed quite sure who would provide the nearly two-week advance notice of any Allied invasion convoy sailing across the English Channel that German defenders were counting on.

As for the S-Boots, they planned to sow the exits to British invasion ports with mines, to delay and whittle down the seaborne invaders. The Luftwaffe and Kriegsmarine did not discuss the S-Boot success at Lyme Bay, and further investigation of the possible connection between the practice landing beaches in England and the connection with the Normandy area were not pursued.

While the tragedy of Slapton Sands was never officially “covered up,” the events of that top secret exercise were not discussed, particularly with the massive D-Day operations coming so soon after. When the war was won, no one was inclined to ruin the celebratory mood by detailing the actions of a bloody failure.

LST Slapton Sands Exercise Tiger 1944 Landing Ship, Tanks (LSTs) were vital to Allied amphibious operations, designed to transport tanks, trucks, and troops directly onto enemy beaches. Their unique hull design allowed them to land heavy vehicles like M4 Shermans and supplies on shallow shores, crucial for the Normandy landings. During Exercise Tiger, these vessels faced deadly torpedo attacks, highlighting the risks of deploying such critical assets in contested waters.
Shown here are Allied troops on the beach during Exercise Tiger. The exercise was intended to be a dress rehearsal for the Normandy landings that would take place in June 1944. Image: NARA

I searched for first-hand information about the action in Lyme Bay, and the following excerpts come from the war report of the USS LST 289:

USS LST 289

Report of action and damage

27 April 1944: At 0104, there were two slight jars felt, about 30 seconds apart — similar to the effect of depth charges at a distance. At 0130 gunfire was observed directed at (LST) 507, about 600 yards astern of us. In the opinion of myself and my gunnery officer it appeared to be 40mm from 2500 to 4000 yards distance, and coming from almost due west, but at no time did anyone see the craft firing…at no time were any flashes observed, making it futile to return the fire.

When we were attacked, we were manning one bow and one stern 40mm, after which we immediately went to general quarters. The firing lasted about 10 minutes and we received no hits out of two or three hundred rounds fired. Shortly after the firing ceased the 507 came back into formation about 700 yards astern of us. At 0203 there was an explosion amidships on the starboard side of the 507, with a great flash of flames that seemed to spread instantly from stem to stern.

Due to the full load of Army personnel for whom we were primarily responsible and our own vulnerability, we considered it unwise to go to the assistance of the 507.

AT 0228 four port 40mms and three 20mms opened fire at what some crews described as a fast white boat, similar to the British ML series, while others were firing at a torpedo wake coming from 315” relative, headed for a point one fourth of the way forward of the stern. The torpedo appeared to be going not more than 15 or 20 knots, and from the Super Conn it seemed that it was going to miss. It didn’t look to be a full-sized torpedo and it was quite close to the surface. It exploded with considerable flash and roar but did not shake the ship noticeably, only a few light bulbs had broken filaments and there were no strained ankles. The starboard stern 40mm tub was blown back on the number five boat davit, and the entire stern section aft the deck house was curled over and onto the navigation bridge aft the signal bridge. It struck sufficiently high that the screws were not damaged.

We had 395 Army officers and men aboard, with 22 “ducks” (DUKWs), a 2 ½ ton truck, and one Jeep. The Army personnel were orderly and cooperative throughout, acting as lookouts and manning the 20mm guns left by the small boat crews.

It is respectfully submitted that this experience has crystalized our ship’s company into an experienced fighting unit with a group morale of the very highest, all of whom have an intense desire to remain together, and upon their behalf I urge that their request be favorably considered.

I cannot speak too highly in praise of my crew, whose cool courage and efficiency during the hours of suspense and danger was worthy of the highest ideals of the U.S. Navy. The engine room watch calmly got the engines started after the explosion. The repair parties were phenomenal in their control of the fire. The small boat crews held up under hours of grueling seamanship. The line-handling parties worked to the point of exhaustion tending the towing lines. The medical corpsmen searched for hours through the hazardous wreckage for the injured. The gunners’ mates crawled throughout the ship in darkness scattered 40mm shells. Every officer was an example to the men in their cool execution of duty. There wasn’t a man who had a physical or nervous breakdown. I am proud of the privilege of being their commanding officer.

– Lt. Harry A. Mettler, U.S. Navy Reserve

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