The seaside town near London with a fascinating World War 2 secret only seen at low tide

The pontoon was intended to be used after D-Day in 1944
-Credit: (Image: Sarah Ide/SussexLive)

Submerged off the coast of a seaside town less than two hours from London lies a fascinating part of British history. Only revealed at low tide, the big concrete structure on Bognor Regis beach has been known to baffle locals seeing it for the first time.

The wreck of a floating pontoon from Second World War was intended to form part of the Mulberry Floating Harbours used to support the Allies' invasion of France on D-Day, June 6 1944. Following the failed Dieppe raid of 1942, the Allied command realised it would be extremely difficult to capture a port on the north French coast.

However, the alternative option to stage the landings along a beachfront posed a logistical nightmare. To get over this problem, two temporary mulberry harbours were constructed off the landing beaches to offload the men and material needed to support the invasion force.

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Although 'Mulberry A' or the Arromanches mulberry was damaged beyond repair by a violent storm just two weeks after D-Day, 'Mulberry B' turned out to be a major success. The harbour off Gold Beach was used for 10 months, with over 2.5 million men, 500,000 vehicles and four million tons of supplies landed before it was fully decommissioned.

It's situated off the Bognor Regis coastline
It's situated off the Bognor Regis coastline -Credit:Sarah Ide/SussexLive

The wreckage between Bognor Regis and Aldwick was partly submerged ahead of the invasion to avoid detection, but Bognor Regis historian Sylvia Endacott says it was never used for its intended purpose in Arromanches.

She told our sister site SussexLive: "Just one day before it was supposed to be towed across the Channel, the pontoon broke free during a storm. It was considered unrecoverable and was abandoned.

"The 'beetle' pontoon was intended to form part of a roadway to allow men and materiel to access mainland F France. There were about fifty of these constructed between Selsey and Bognor Regis ready to be towed on D-Day.

"So many people from the town today have no idea what it's all about. It's not like a shipwreck which people can easily make out. I just find the concept of these structures incredible. The fact that a concrete block could float across the Channel."

It was only discovered after a bad storm
It was only discovered after a bad storm -Credit:Sarah Ide/SussexLive

It can now be seen 500 metres west of the beach huts at Fish Lane, and about 100 metres offshore. It is the only surviving remnant of a 'beetle' pontoon left in England.

Another wrecked element of the mulberry harbour lies off the Sussex coast between nearby Pagham and Selsey. The 'caisson' pontoon - intended for use as a 'breakwater' to improve sea conditions for landing soldiers - sits 10 metres underwater and is a popular scuba diving spot.

Sylvia Endacott added: "The floating caissons are especially remarkable.

"The 60ft tall, 204ft in length and 50ft wide structure was able to float because they used a water-tight chamber open at the bottom which contained air under pressure."

The concrete structure is situated on the beach between Bognor Regis and Aldwick. It's about a one hour and 45 minute train journey from London Victoria.

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