Located off shore on the Thames estuary, the Maunsell Sea Forts are some of the most bizarre-looking structures. They are named after the civil engineer that designed them, Guy Maunsell.

The forts had a very short but intense life during World War II when Great Britain faced serious attacks from the Luftwaffe. There was little that could be done on land to counteract the on-going attacks on the naval infrastructure.

The Maunsell Sea Forts were built in 1942 and decommissioned in the 1950’s. They were left abandoned in 1958 but some of them still stand to this day.

Although collectively known as Maunsell forts, there are two distinct designs with different purposes. Closer to the mainland there were three-three army forts on the Thames estuary and on the Mersey. Further offshore there were another four naval forts in the Thames estuary. The army forts consisted of seven circularly shaped forts that were connected through a walkway. The naval forts have two cylindrical towers that are united by a gun platform above.

The Naval Forts

The first forts to be deployed were the four naval forts that were built between February and June 1942. These forts housed 120 men each, mostly below the waterline. These structures were built onshore and sunk into their position offshore. The naval forts were single structures that had seven floors. Each fort had Bofors guns and a radar.

Out of the original four naval forts only two survived to this day. One of these last two forts currently hosts the self-proclaimed Principality of Sealand.

The Army Forts

In 1943 Guy Maunsell designed a new type of fort that looked more futuristic. Each fort consisted of a central control tower linked to six “satellites”.

Out of the three army forts situated in the Thames estuary, the Nore Army Fort was closest to the shore. This army fort is the only one that no longer exists as it was badly damaged during the 50’s and was demolished by 1960.

The Red Sands army fort is made up of seven forts that were linked by walkways. There is an on-going effort to restore the Red Sands army forts because they are considered to be in the best condition.

Located over 9 miles away from the shores, the Shivering Sands Army Fort currently stays abandoned. Out of the seven forts built here, only six stand today after one of the forts was hit by a Norwegian boat in 1963. It served as the location of the first pirate radio that broadcast from the Maunsell forts. Its future is uncertain but there are plans to dismantle it.

Right after the war they were put under maintenance, but soon they lost any strategic importance and were used in different ways. To learn more about the stories of the forts head to the page about Maunsell Sea Forts History.