In April 1943, Fritton Lake was requisitioned by the 79th Armoured Division as part of the top secret plans associated with the D-Day landings.
Tanks were modified to make them amphibious, to enable them to swim to the Normandy Coast and provide close fire support to the infantry on the first assault wave. Buoyancy was achieved by attaching a collapsible screen, inflatable rubber columns and a tubular framework of steel, which enclosed the upper portion of the tank. Propellers fitted to the rear of the tank provided propulsion when waterborne and also gave the tank its code name: Duplex Drive or D. D. for short.
Their development can be attributed to Hungarian designer, Nicholas Straussler. However, the training and further trials was achieved under the leadership of Major General Percy Hobart KBE., CB., DSO., MC., who was the Commander of the 79th Armoured Division.
Hobart required an inland lake to conduct the elementary training with the Duplex Drive tank, and chose Fritton due to its wooded shores, open water of 180 acres and its proximity to his other top secret facilities at Orford and Sudbourne in Suffolk. Fritton became known as A Wing and was referred to as the Fritton Bridging Camp. Its cover story involved the transport of vehicles and equipment by means of ferries and Bailey bridges. Even those local to the lake had to sign the Official Secrets Act, preventing them from disclosing any details of what they saw, and inhibiting access to their properties by everyone, except close family and doctors.
Between 6th April and 10 June 1943, engineers undertook the construction of tank parks, mock up landing craft ramps and a hutted camp for personnel. Fifty Valentine Duplex Drive tanks were stationed at Fritton along with workshops and stores. In addition, a special facility was constructed to enable crews to practice escaping from a submerged tank. One hundred and twenty full-time soldiers were stationed here, to instruct the crews, to maintain the tanks and equipment, and to patrol the site.
Over the ensuing months a total of ten regiments attended the Fresh Water School. Their intensive training lasted 14 days, and enabled the crews to perfect launching drills, navigating and landing procedures. In addition, the crews had to learn to waterproof the tank, repair the screens and maintain the drive system. There were five British crews, including the 4th/7th Dragoons, East Riding Yeomanry and 13th/18th Hussars; two Canadian Tank Brigades (6th Armoured Brigade (1st Garry Horse) and the 10th Armoured Regiment (1st Hussars) and three United States tank units/battalions (70th, 741st, 743rd). The crews were billeted in hotels and bed and breakfasts in Great Yarmouth whilst at Fritton, before being sent to a second establishment, B Wing: Salt Water Wing at Gosport, Hampshire.
It was during the training of the 743rd United States Tank Battalion that Supreme Allied Commander, Dwight D. Eisenhower, along with Field Marshall Alanbrooke met Hobart to inspect the 79th Armoured Division’s training facilities on the East Coast.
Eisenhower arrived on the overnight train from London and arrived at 0845 hours at Saxmundham Station in Suffolk on 27th January 1943. Their first port of call was Hurst Hall at Saxmundham, which was the headquarters of the 79th Armoured
Division, where the party were briefed about the secret and experimental nature of Hobart’s division. Visits and demonstrations of the various specialised equipment was conducted, including a tank that destroys mines (Sherman
Crab/Flail Tank), Armoured Ramp Carrier (for overcoming sea walls and concrete obstructions) and the Crocodile (a flame throwing tank that was able to shower gun implements with burning liquids with terrifying consequences). The modified tanks were nicknamed, Hobart’s Funnies.
Lastly, Hobart, Alanbrooke and Eisenhower visited Fritton. Not only did they witness the various stages of training, including an amphibious tank escape, but also Eisenhower rode on a Duplex Drive Valentine into the lake via one of the landing craft mock ups. It is recorded that he stood on the commander’s platform and operated the rudder, steering the tank during manoeuvres.
The effectiveness of the Duplex Drives was proven on D-Day when 176 Duplex Drives were launched into the English Channel in the early hours of 6th June 1944 and 121 landed successfully on the five assault beaches. Never before had tanks participated so early in an assault, and, to use Hobart’s words: these tanks proved to be the key to unlocking the gateway to Europe.