The Maunsell Forts are armed offshore towers built in the Thames waters during the WWII in order to help defend the United Kingdom from the Nazi invasion. They were operated as navy and army forts and named after their designer, Guy Maunsell.

These military forts were a part of the Thames defense network, primarily designed to be the anti-aircraft tower-forts. There were six forts in the past.

The Maunsell Forts were operated by the Royal Navy, to report German air raids and to prevent attempts to lay mines by aircraft in this important shipping channel. This human-made naval installation is similar to early “fixed” offshore oil platforms. The overall weight of the installation is estimated to approximately 4500 tons.

During the World War II, the Thames estuary Navy forts only destroyed 1 German E Boat.

There where four sea forts back in the day:

  • Rough Sands (U1)
  • Sunk Head (U2)
  • Tongue Sands (U3)
  • Knock John (U4)

Maunsell Army Forts are primarily designed to be anti-aircraft forts, in order to protect the mainland from the common Nazi air raids during World War II. Back then, there were three of these forts, but only two are left standing.

Redsands Fort – In this fort there are 7 towers, located at the mouth of the Thames Estuary. All these towers were previously connected by metal grate walkways. It’s currently the only fort that can be accessed safely from a platform in between the legs of one of the towers.
Shivering Sands Fort – These towers were built on land and floated out in 1943. During the war, equipment was replaced and removed soon after. In 1964 Screaming Lord Sutch set up a pirate radio station (Radio Sutch) on one of the old towers.

The Shivering Sands Fort was occupied by the artist Stephen Turner for 6 weeks in 2005 and described the project as an experiment in isolation and also wrote a blog and a book about it.