A series of steel and concrete forts were built by the British in the estuary of the Thames during World War Two. With all I have read about Great Britain and the German Navy in World War Two, I had never heard of these forts much less knew several still existed.
From Der Spiegel:
Clusters of steel huts and manned triumphal arches: From bizarre fortresses off the coast, the British military fought German mine layers in World War II. The huge forts weren’t just a thorn in the side of Hitler’s air force, but also drove their British crews insane…
WHITSTABLE, UNITED KINGDOM – JUNE 30: General view of Redsand towers on June 30, 2006 in Whitstable, England The Redsand Towers, coded “Uncle 6” during WW2 were built to protect supply ships from the German magnetic influence mines. The forts succeeded in shooting down 22 planes and 30 flying bombs. In 1964, Radio Caroline began broadcasting from a ship moored outside UK Territorial Waters this prompted as series of other pirate stations including Radio 390 based on Redsand. (Photo by Bruno Vincent/Getty Images)
A squad of British soldiers march round the deck of a sea fort, located several miles off the Mainland “somewhere in the Northern Command” on Feb. 28, 1942. They man batteries of coastal artillery on the fort and undergo a rigorous training to fulfill their mission. (AP Photo)
Standing 50-feet above the water, this is one of the seven-towered sea forts erected in the Thames Estuary by the British as protection against mine laying by German planes in an undated photo. The forts are 36 feet square, 20 feet deep and stand on concrete stilts. They’re armed with 3.7 anti-aircraft guns, bofors guns, and other equipment, some of which has been whited out by censor. (AP Photo)
[Source and Images: Der Spiegel.]