Based in the Thames and Mersey estuaries, the Maunsell Forts were built during the Second World War to defend the United Kingdom. Operating as navy and army forts, they took their name from their designer, Guy Maunsell.

They were decommissioned in the 1950s and have since been used for other activities, including pirate radio broadcasting. The forts were built at river mouths across the UK to defend against attacking naval forces.

Rough Sands Fort

The first of the four original forts to be built designed by Maunsell, the Rough Sands Fort resides on a sandbar located around 10 kilometers off the coast of Suffolk. It played perhaps its most important role after the war, as it was here in 1966 that Ronan O’Rahilly and Paddy Roy Bates landed, occupying the entire fort. After a disagreement, Roy Bates seized the tower as his own and defended his new territory with guns and petrol bombs when anyone attempted to take it from him. The British Royal Marines were put on alert and the authorities ordered Bates to surrender. He did not, and he and his son were arrested; however, the charges were overthrown has the court did not have jurisdiction. Bates returned to the fort and founded the Principality of Sealand on 2nd September, 1967. Seven years later, he issued a flag, national anthem, and constitution.

Sunk Head Fort

The Sunk Head Fort was situated around 20 kilometers off the coast of Essex. Ironically, most of it has since been sunk. After fearing it would meet a fate similar to that of some of the other forts, and not wanting it to be taken over by offshore broadcasters, the government sent a contingent of forces under the command of Major David Ives to destroy it. It was weakened by cutting torches and around 3,000 pounds of explosives were set around the structure. It was blown up on 21st August, 1967, the same year the Principality of Sealand was founded.

Tongue Sands Fort

Approximately 10 kilometers off of the coast of Margate, this fort has also since been destroyed. Of all the forts, this is the only one attributed with a confirmed kill or destruction of an enemy vessel. In 1945, fifteen German U-boats appeared on the radar. Tongue Sands Fort pummeled them with heavy fire from its 3.7” guns. The enemy combatants, confused as to from where they were being attacked, began evasive maneuvers, with one boat actually crashing into another, sinking the vessel. The fort’s destruction was not intentional; over the course of the years, it took on a 15-degree list and on the 5th December, 1947, began to shake violently before falling into the sea. The caretaker staff was rescued by the HMS Uplifter after putting out a distress call.

The forts stand as testament to the ingenuity, quick fabrication methods, and sturdiness of wartime construction. They are an incredibly interesting sight for anyone able or willing to make the trip.