THE 75th anniversary of the D-Day rehearsal Operation Smash, the largest live-fire exercise of World War II, has been marked with two poignant memorials.

Six men died in the exercise, held off the Studland coast, while manning top secret amphibious Duplex Drive Valentine tanks.

These tanks were designed to be 'floating' units, able to leave their landing ships further from shore compared to other tanks.

As the exercise unfolded on April 4, 1944, Prime Minister Winston Church, King George VI and General Dwight D. Eisenhower – Supreme Commander of the Allied Forces – looked on from Studland's Fort Henry.

Six of the tanks sank, with the loss of six lives.

More than 50 people, including family members of the men that died, regimental representatives and ex-regimental members, gathered at Ford Henry for a service of remembrance on Thursday. (April 4)

In the driving rain they paid homage to the men who went to the bottom of the sea 75 years ago.

Earlier in the day serving members of the Royal Dragoon Guards and representatives of the Valentine 75 Project took a vessel out to sea and laid two wreaths on the water at one of the tank wreck sites. The plan had been to dive down to each of the six wrecks, but the poor weather prevented this from taking place.

The memorial services marked the culmination of two years work by the Isle of Purbeck Sub-Aqua Club (IPSAC), the organisation that launched the Valentine 75 Project to map the history of the tanks and their crews that perished.

Valentine 75 Project officer Nick Reed said: "I made the decision to call of the dives when we saw how bad the weather was, but we took a boat out to one of the wreck sites with serving members of the Royal Dragoon Guards, and were able to lay two wreaths on the surface.

"There were also more than 50 people, including family members, regimental representatives and ex-regimental representatives at the service at Ford Henry."

An exhibition was held at the National Trust's Visitor Centre at Knoll Beach, Studland, to coincide with the commemorations

"We've had more than 1,500 people coming to the exhibition," said Mr Reed. "Initially the project was going to end with the 75th anniversary, but it will continue now. There is still just so much to learn.

"It has become a passion, or possibly as my wife says, an obsession."