Located near Sortosville-en-Beaumont between Barneville and Bricquebec off the D902 road, this site was one of six early radio guidance sites built in France to support bombing raids on England.
In order to improve the accuracy of night-time or low visibility bombing raids, German forces developed a system known as Knickebein – their first-ever radio guidance system – which broadcast medium frequency radio beams from large antennas based at strategic locations.
Knickebein translates to ‘bent leg’ or ‘crooked leg’ and refers to the dog-leg shape of the FuSan 721 antenna used to broadcast the radio beams.
The beams were based on morse code and were a series of dots and dashes which could be detected by a lead aircraft in a bombing raid. If the aircraft detected dots or dashes, they knew they were off target to the left or right and it was only when the radio operator/navigator onboard heard a single tone that they knew they were in direct line of flight to their objective.
A third beam would also be broadcast to enable the aircraft to determine the range to their target and it’s believed the system enabled the bombers to deliver their payloads within a 1.5km radius of accuracy – far better than previous unguided raids.
By June 1940, British intelligence services had detected the broadcasts and were able to jam the signals destroying the accuracy of raids, leading the Germans to develop more precise and robust systems including the X-Gerat and later Y-Gerat guidance systems.
The Luftwaffe-run facility at Sortosville – known as site K10 - featured a large FuSan 721 type antenna mounted on a 10m diameter circular track plus a crew bunker where there would also be a large generator and ‘computing room’.
The main bunker here has two entrances, and one still features a large German eagle above the doorway with the remains of original concrete lettering in place. The inscription originally said: “Built under Adolf Hitler, in the fight against England.”
Inside this supporting bunker you can work your way through several large comms and crew rooms, a generator area where large banks of batteries would be housed, and a toilet and shower room.
The rooms where the generator and batteries once stood, and the main comms rooms, all feature tiled walls and it’s believed that this is to prevent any accidental spillages of batterie acid reacting with the concrete and giving off noxious gas.
Along with the miles of cabling inside, the generator and batteries would give off a lot of heat and there are four large cooling chimneys on the roof of the building which can be seen and accessed with care.
From the top of the building, you can also see into the field where there are three tie-downs for a large aerial and a concrete water storage reservoir.
The antenna track outline can still be seen today near the wind turbines, although the field it stands in is now off limits for safety.
The other five sites in France can be found near Cherbourg, Caen, Dieppe, Brittany, and Boulogne with other Knickebein stations in The Netherlands, Germany, Italy, and Norway.