"Maunsell" fort HMFort
Sunk Head
This Maunsell fort is one of four submersible forts that were placed in the Thames estuary, built with a concrete hull-shaped pontoon two large cylindrical towers hosing the magazines & stores, crew and machinery (the latter above the waterline), topped with a simple steel superstructure. Though fitted with two Army 3.7” AA Mk IIC and two 40mm Bofors guns, it was designed to the specifications of the Admiralty , had one Navy radar (in the lantern), and operated by a Navy crew . Once grounded, the forts would not be able to refloat themselves, but were immediately ready for action. With a shortage of riveters with a heavy demand in shipping construction, the structure of all forts was bolted, not riveted, and with the use of reinforced concrete these forts are a tribute to British ingenuity.
This image shows the fort HMFort Sunk Head being towed to her berthing place by the tugs Challenge, WaterCock & Crested Cock (just out of the frame in the lead); the smaller craft is a Harbour Defence Launch. Challenge---who participated in the Dunkirk evacuation--- has been preserved and is currently undergoing maintenance; I’ll certainly pay her a visit once she’s fully open to the public.
When the Army required a series of forts of their own, they pushed Maunsell to base the design on the layout as on land with an arc of four 3.7 guns ahead of a command post backed up by a searchlight. This resulting in a total 6 Army forts comprising 7 towers each supported by 4 concrete legs; the first three were placed in the Mersey estuary.
The forts managed to shoot down a collection of about 22 aircraft and V1 rockets and participated in skirmishes with German E-boats; one E-boat was sunk, probably after colliding with another E-boat in the utter confusion that followed when the forts opened fire.The forts were abandoned after the war and reclaimed by a number of pirate radio stations (some of which still operate today from a less clandestine location). HMFort Roughs’ Tower has had the most notorious history by hosting the micro nation “Principality of Sealand”.
The forts in the Thames are still here today and you can visit them by boat trip. There’s plenty to find online. The research of the forts has been published by Frank R. Tuner and his books pop up on Ebay regularly.
