Exercise Tiger: D Day’s Untold Deadly Dress Rehearsal | History Hit

Exercise Tiger: D Day’s Untold Deadly Dress Rehearsal

Amy Irvine

29 May 2023
American troops landing on Slapton Sands in England during rehearsals for the invasion of Normandy in Exercise Tiger, 25 April 1944
Image Credit: Wikimedia: United States Library of Congress's Prints and Photographs, ID cph.3c32795 / Public Domain

The D-Day landings of 6 June 1944 were the largest amphibious landing in the history of warfare – and had required planning and large-scale rehearsals. From 22-30 April 1944 the Allies launched Exercise Tiger. The aim was a closely choreographed practice assault landing, yet the result was a disaster, with the deaths of 946 American servicemen.

What went so wrong, and why did the incident largely remain secret for decades to come?

The D-Day landings of June 6 1944 were the largest amphibious landing in the history of warfare, and are famed as a major turning point towards Allied victory. But they weren’t without planning and practice. In late April 1944, the Allies launched one of their trial runs, Exercise Tiger, off Slapton Sands in Devon. The aim was a closely choreographed landing, the result was a disaster. Hear Dr Harry Bennett from the University of Plymouth discussing the players in this trial run, and how it became the Battle of Lyme Bay.
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Why Slapton Sands?

In November 1943, the War Cabinet ordered the evacuation of villages surrounding Slapton Sands (30,000 acres and 3,000 local residents). Selected for its resemblance to the area between Pouppeville and La Madeleine in Northern France – codenamed Utah beach – the British government then set up a training ground there to be used by the American Force “U”, tasked with landing at Utah.

Slapton Sands in Devon – site of Exercise Tiger

Image Credit: Shutterstock

Exercise Tiger begins

30,000 American troops took part covering all aspects of the invasion. Landing craft were deployed along the coast, including 9 landing ships for tanks (LSTs, nicknamed ‘Large Slow Targets’ by soldiers) – with the area protected by the Royal Navy, who also monitored the Cherbourg area where the German E-boat threat was based.

22-25 April focused on marshalling and embarkation drills. On the evening of 26 April the first wave of assault troops set-off to simulate the Channel crossing, travelling through Lyme Bay to arrive at Slapton at first light on 27 April.

Friendly fire

H-hour was set for 07:30. The exercise was vital, and thus designed to be as realistic as possible – including using live ammunition to acclimatise soldiers to naval bombardments 50 minutes prior to landing. During the landing, live rounds were to be fired over the heads of the incoming troops by forces on land to harden them to real battle conditions.

However, several of the landing ships that morning were delayed, leading American Admiral Don P. Moon to decide to delay H-hour for an hour until 08:30. Tragically some landing craft didn’t receive word of the change, landing at their original scheduled time. Consequently the second wave came under live fire.

Attack by German E-boats

Furthermore, in the early hours of 28 April, Convoy T-4 was attacked by German E-boats in Lyme Bay, who’d managed to avoid detection.

Of the two ships assigned to protect the convoy, only one (HMS Azalea) had been present. The second (HMS Scimitar), had been in a collision earlier with an LST and had left the convoy for repairments. This wasn’t known by the Americans as their LSTs and British naval headquarters operated on different radio frequencies. HMS Saladin had been dispatched as a replacement, but didn’t arrive in time.

A German E-boat similar to ones that attacked the convoy during Exercise Tiger (pictured here flying the white flag, after surrender at the coastal forces base HMS Beehive, Felixstowe, May 1945)

Image Credit: Photograph A 28558 from the collections of the Imperial War Museums / Public Domain

The aftermath

In total, 946 US servicemen (551 Army, 198 Navy) were killed during Exercise Tiger. Many drowned or died of hypothermia in the cold sea while awaiting rescue. A large portion hadn’t been shown how to wear their lifebelt correctly, meaning the weight of their combat packs flipped them upside-down, dragging their heads underwater and drowning them.

Eisenhower was enraged – not only about the tragedy, but also that the convoy had been sailing in a straight line and there were now reduced reserves of LSTs – not to mention the events now indicated to the Germans that the Allies were nearly ready to invade. 10 American officers with knowledge of the D-Day plans were missing. Worried they could have compromised the invasion if they’d been captured alive, the invasion was nearly called off until all their bodies were found.

Merely knowing that exercises were taking place at Slapton interested the Germans, and may have contribued to Hitler’s insistence in May to reinforce Normandy. Shore batteries around Salcombe Harbour had spotted unidentified small craft, reporting German S-boats nosing through wreckage for information. Orders were given not to fire to avoid disclosing Allied positions revealing the harbour was defended.

Dan talks to Giles Milton about D-Day and what his research has uncovered about the untold stories of this landmark event.
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Concern over potential leaks just prior to the impending real invasion of Normandy meant the true story of the incident remained under the strictest secrecy.

Only nominally reported afterwards, little information is contained in official histories about the tragedy. Rather than a cover-up, some think the event was just ‘conveniently forgotten’. Casualty statistics from Exercise Tiger were only released in August 1944, along with the actual D-Day casualties, and debates continue over their reliability. A press release went largely unnoticed in light of the larger events occurring at the time.

It was only in 1974 that Exercise Tiger drew greater recognition when Devon resident Ken Small discovered a submerged tank from the 70th Tank Battalion. Ken bought the rights to the tank from the US Government and raised it in 1984 – it now stands as a memorial to the incident.

Slapton Sands, Devon at the Torcross memorial for Allied Soldiers killed during Exercise Tiger.
The a M4A1 Sherman tank was raised from the sea bed in 1984.

Image Credit: Public Domain

Implications for D-Day

As a result of Exercise Tiger, radio frequencies were standardised, landing troops received better lifevest training, and plans were made for small craft to pick up floating survivors on D-Day itself.

Ironically the loss of life from Exercise Tiger was greater than during the actual invasion of Normandy. Despite the tragedy, lessons learned no doubt saved countless lives on D-Day, facilitating the turning point for the eventual Allied victory.

Amy Irvine