SOME Dorset residents were affected by Exercise Tiger, a wartime mission in Lyme Bay.

A few days ago the 71st anniversary of the Second World War tragedy was commemorated.

The anniversary this year of the D-Day rehearsal for an invasion of Normandy's Utah Beach took on extra significance as marine robots surveyed the wreckage of two US Landing Ship Tanks (LSTs) that were torpedoed and sunk on April 28, 1944.

On that date eight tank landing ships, full of US servicemen and military equipment, converged in Lyme Bay, at Slapton Sands, Devon, making their way towards Slapton Sands for the rehearsal.

But a group of German E-Boats, alerted by heavy radio traffic in Lyme Bay, intercepted the three-mile long convoy of vessels, resulting in the loss of nearly 1,000 American servicemen's lives - more than the number of lives lost at the actual Utah Beach invasion.

The mission has produced the first high-definition sonar images of this World War II tragedy which can be seen here.

This was the first time in history that an AUV had surveyed the area.

The REMUS 100 used for the mission is designed to perform intricate oceanographic surveys over large areas.

The data shows that both LSTs are about 50 metres below the surface in Lyme Bay and reach between six to eight metres above the sea floor.

To commemorate the anniversary of Exercise Tiger, Hydroid and the Royal Navy will be donating images obtained from this mission to the UK National Archive and local memorials.

Richard ‘Bungy’ Williams, regional manager at Hydroid Europe said: “We hope that the data collected on this mission will shed additional light on this tragic event and help bring some closure to the families who lost their loved ones during Exercise Tiger.

“We are proud to use our technology to honor the memories of the servicemen who lost their lives in this tragic operation.”