THE sunken Valentine tanks which lie beneath the waves off the Studland coast have been given special protection by the government, to mark the 75th anniversary of D-Day.

Six weeks before D-Day, which would become the largest seaborne invasion in history, troops arrived at Studland Beach to rehearse the assault to come.

Codenamed 'Operation Smash', this live-firing exercise – the biggest of its kind of World War II – was watched by Prime Minister Winston Churchill, King George VI and Supreme Allied Commander General Dwight D Eisenhower – from Fort Henry, an observation post overlooking Studland Bay.

Seven army tanks known as Duplex Drive (DD) Valentine tanks were lost during this exercise which went badly wrong. The Valentine was modified to be a ‘floating’ or amphibious tank that could leave its landing ship further out from shore than other tanks.

However, during the exercise these tanks sank with the loss of six crewmen shortly after driving off their landing craft.

They ran into immediate difficulty when a sudden change in the weather adversely affected sea conditions.

A valuable lesson was learned that these tanks couldn’t survive being launched too far from a beach and consequently on D-Day itself the tanks were released in shallow water.

The Valentine tanks in Poole Bay represent the largest surviving group of their type anywhere in the world.

The tank sites are among a number of historic sites linked to D-Day to be offered special status, on the advice of Historic England.

These include armoured bulldozers and surviving components of Mulberry floating harbours along the south coast.

Culture Secretary Jeremy Wright said: "As we commemorate the 75th anniversary of D-Day, it is right that we continue to honour the memory of those who fought for peace in one of the decisive moments of the Second World War.

"It is also right to recognise the engineering and ingenuity that enabled that offensive.

"By listing the landing crafts, tanks, bulldozers and floating harbours we can ensure that future generations can learn about this important moment in our history."

Historic England chief executive Duncan Wilson said: "Evidence of D-Day planning, rehearsal and the actual operation is all around us, on our coastline and in our waters helping to tell the D-Day Story.

"These tanks, armoured bulldozers, Mulberry Harbour components and concrete training landing craft are important as a witness to the great engineering achievements and logistical preparations around England’s coast for the largest amphibious invasion ever undertaken, on 6 June 1944.

"It is vital that we protect them as a memorial for future generations."