Maunsell Sea Forts of the Thames Estuary

 Thursday, 8 May 2014, by Frank Turner

Innovative, pioneering, and practical, Guy Maunsell (1884-1961) was a talented civil engineer denied the recognition due to him, yet his Maunsell forts (small fortified towers) helped stave off enemy incursion into home waters during World War II.

The four sea forts, operated by the Royal Navy, were Knock John, Rough Sands, Sunk Head, and Tongue Sands. Seven anti-aircraft forts, operated by the Army, were sited in the Mersey (four forts) and Thames Estuary (three forts), these latter being Nore, Red Sands, and Shivering Sands.

The necessity arose early in the conflict, when the Germans employed influence mines with great success in the important shipping lanes from Harwich to the Thames Estuary, these mines being immune to minesweeping. Our Government spent enormous sums in seeking a remedy, initially commandeering pleasure steamers, which were equipped with Bofors guns, and fitting a Wellington bomber with a large circular copper modification capable of radiating a mine de-activating signal.

Several different proposals from Maunsell were rejected by the Admiralty, but Maunsell personally approached Admiral of the Fleet Sir Bruce Fraser, who directed the Civil Service to place an order. Constructed at Gravesend (a labour force of five hundred being drawn from the Dartford, Gravesend, and Sevenoaks areas), the naval forts were designed as a pontoon barge bearing two cylindrical towers surmounted by a gun platform. Air-conditioned and centrally heated, each tower accommodated 60 men, sleeping 15 to a room. Armament consisted of two 3.75-inch guns and two 40mm Bofors guns, and each tower was 24 feet in diameter and 60 feet high, with 1-inch thick walls. The completed forts were towed out and sunk into position with their crew on board.

Weighing 4,500 tons, the forts were manned by 3 officers and 120 men, working 6-week shifts, 16 hours a day. Inevitably, such an existence created mental health problems, it being vital that each man have a consuming hobby (which was supervised). Some took up knitting, others built models or angled for fish, while Maunsell insisted that the men have comfortable bunks, rather than hammocks, and that the décor of the walls be a restful gloss green.

Sneak-raids on the Mersey from the Irish Sea caused a need for further forts. These anti-aircraft forts were constructed as a series of interconnected steel platforms with a ½-inch thick steel house for the crew. These were also air-conditioned, with windows which could be opened, and a complement of 165 men working 6-week shifts, followed by 10 days ashore undertaking route marches! Each fort carried four 3.75-inch guns and two Bofors 40mm guns. Unsurprisingly, the highest desertion rate in the British Army during the war concerned those manning the Thames forts. In the 1950s, the anti-aircraft forts were decommissioned by the MoD.

In 1953, a Norwegian vessel collided with Nore, causing extensive damage and four fatalities; Nore was dismantled during 1959 and 1960, the ruins of its bases currently sited near Cliffe village. Shivering Sands was lost in 1963 in similar circumstances, Sunk Head fell to the RE a few years later, while Tongue Fort collapsed in a 1996 storm. Project Redsands, owned by Frank Turner and his associates, has received a £50,000 donation from Mowlem and paint supplies from B&Q, to help preserve the fort and address the need for modern installations, refurbishment, and anti-rust protection. No weapons remain, of course, the 3.75-inch guns having been removed to Scapa Flow in 1956, except for one adorning Gravesend promenade.

Two naval forts were exploded by the Army, only Knock John and Rough Sands remaining, the latter having been acquired by the late Major Paddy Bates, who declared it the independent ‘Principality of Sealand’, issuing its own passports, driving licences, postage stamps, and coins.

Maunsell’s name may not be familiar, yet his inventiveness applied considerable ingenuity to the war effort. Undoubtedly, his forts were costly to construct and bad for crew morale, yet they accounted for 22 aircraft and 30 flying bombs, which could have created wide scale damage and loss of life. Certainly, his contribution to England’s defence should not be forgotten, his name living on whenever we speak of the two remaining Maunsell forts.

Stefan Gatward