German boats successfully stopped D-Day landing practice

A stunning German attack on Exercise Tiger for D-Day inflicted 700 deaths, worse than the same forces would suffer on the real D-Day.
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American troops landing on Slapton Sands in England during rehearsals for the invasion of Normandy.

In November 1943, Adolf Hitler gave a legitimately smart order. The mustachioed, racist madman issued Directive Number 51, ordering a strategic pivot from their eastern front to the west. Basically, he wanted Germany’s forces to focus on preventing an American and British landing and reduce the focus on the Soviet Union. The Kriegsmarine eventually ordered that all vessels risk themselves to prevent Allied success. And they hit pay dirt with Exercise Tiger.

And, on the night of April 27, a group of German S-boats patrolling near the coast of England found an American flotilla practicing to land at D-Day. They launched an attack that led to approximately 700 American deaths. Worse, Allied miscommunications led to another 300 friendly fire deaths.

More Americans died in the fraught practice for Utah Beach than at the actual assault on Utah Beach. Here’s how it happened.

The German preparations for a landing

We’re big fans of pointing out how stupid and ill-prepared for leadership the Nazis were. Just looking at Hitler, he was a drug addict who faced multiple assassination attempts, had smelly pee, made a dumb attempt at invading the U.S., relied on a Jewish test pilot, was obsessed with Clark Gable, and launched an invasion while its industrial base was weak.

But every once in a while, even the horribly groomed, occult-obsessed Hitler made a good decision. And we have to admit that desperately launching his remaining navy and nearly eradicated air force into the West did pay off.

The Germans sent some of their few remaining Luftwaffe reconnaissance planes to the southeast coast of England. Those reconnaissance planes found a lot of evidence of the upcoming landings.

According to a Navy history:

What German reconnaissance saw was the military buildup in Exercise Tiger’s staging area—the harbors and inlets around Portsmouth. At Spithead roadstead, the Germans counted more than 200 trucks. In and around Southampton, they observed ships, including destroyers; troop transporters; and a great many LSTs and land vehicles. At Portsmouth Harbour, the Germans sighted cruisers, destroyers, and smaller vessels and vehicles. At Pagham, Chichester, Langstone, and Exbury harbors, as well as in the mouth of the river Hamble, the Germans spied still more landing vessels.

Exercise Tiger: Disaster at Slapton Sands,”

But a lot of those ships had a prior mission first. Force U had orders to practice a shore landing. Force U would land at Slapton Shores in hyper-realistic conditions. It would compile lessons learned and apply them before its D-Day mission at Utah Beach.

The practice landings were named Exercise Tiger.

And Germany knew that those American and British vessels would be on the move at some point.

Exercise Tiger

Force U and Exercise Tiger made the landings as realistic as they could. They loaded the vehicles with fuel. Troops carried their full combat load. The landing ships were completely filled with weapons, vehicles, and soldiers. Both inland artillery and naval artillery used live ammo for the exercise.

And the S-boats went on patrol to look for them. Unfortunately, the German S-boats, fast attack craft armed with torpedoes, found the force.

The first troops of Force U hit the beaches on the morning of April 27. Follow-on waves hit the beaches throughout the day and into the night. Overnight, a convoy of eight LSTs approached the beach. But that was the one the S-boats found.

The German Schnellbootes, also known as S-boats or E-boats, rarely fought in groups of more than 30 or so. But they could inflict serious damage for a few moments or hours if they caught a convoy unawares.

The boats that attacked overnight April 27-28 were spotted multiple times, but the soldiers and ships’ crews taking part in the exercise were in the dark, literally and figuratively. In the dark of night, unsure of which ships were involved in the exercise, and unable to use their radios except for emergencies, the forces that spotted the nine S-boats failed to report the threat or respond to it.

When the nine S-boats spotted the eight LSTs, they lined up for a torpedo attack. At least one, LST-507, sighted green tracer fire and ordered its crew to battle stations.

exercise tiger tank
Sherman DD tank at the Torcross memorial.

The German attack on Exercise Tiger

At just past 2 a.m., the Germans launched the first torpedo at LST-507 and got exceptionally lucky. The torpedo slammed right into the auxiliary engine room and cut all of the ship’s electric power. Soon, the order to abandon ship rang out.

As one officer remembered:

The assistant navigator and I jumped over the side of the LST into the near freezing water 25 feet below. The sea around the ship was covered with an oil slick from the badly damaged LST, and the surface was on fire.

Steve Sadlon, as quoted in

Soon, another salvo of torpedoes passed right under one LST and then shredded another.

A flare broke over our head, over our ship. I said, ‘Oh my god, we’re gonna get it.’ And apparently we didn’t. It must have gone under us, see, because [the] LST was a flat-bottom boat. I looked to the stern and saw LST 531 or 532 get torpedoed.

Paul Gerolstein, in NPR

It was LST-531, and it sunk in about 10 minutes after two torpedoes hit it.

A final attack against LST-289 did serious damage to the ship but left the crew alive. The crew managed to make it to shore.

With the ships of Exercise Tiger widely spaced out and the LSTs ordered to a different radio frequency than the shore installations and one escort ship, few realized that a real fight had broken out.

The Fallout

It took two hours for rescue and response to get underway. And when it did, the rescuers didn’t have most of the normal tools for fighting extreme hypothermia.

Officers and historians attempted to figure out the death count. Numbers vary, but most historians today think the losses were about 700. Compare that to an actual Utah Beach casualty count on D-Day of 197 dead and wounded.

Miraculously for the actual landings, every deceased officer with Top Secret documents on their person was found, meaning that the real landing plans were safe from Nazi discovery.

But the Army and Navy did learn from the disasters. They remade the communications plans to get rid of the chaos and miscommunications from Exercise Tiger. The military got better life preservers and trained soldiers in their use and in ship evacuations.

Most importantly, the Allied air forces launched a campaign to annihilate and cage up the S-boats before D-Day. The campaign was largely successful and prevented a serious raid on the actual D-Day beaches.