The Atlantik Wall In Normandy
Fort Allemand Mao 1211O
This was never a fort, but after the German invasion the local population were excluded from all sensitive sites such as this and
it became known as “ The German Fort”.
On the same day that this region of France fell to the invading Germans they were seen surveying this site. (June 18th 1940)
They needed a site on high ground on which to build a new and early form of radio guidance, permitting planes to fly by night.
Radio navigation systems had been in use for a few years, used by both military and civilian aircraft.
This usually took the form of a transmitter at the destination or on the route, and the plane flew along the signal.
This could be used for bombers returning home after a mission, but could not obviously be used on the outward leg.
It was also very inaccurate for a flight of over 200 kms, so the reverse of this system was needed.
The Germans were the first to use such a system (Knickebein) and the two navigation beam transmitters were installed here and at Beaumont Hague near Cherbourg.
The transmitter here was operational in late 1940, and were first used for the bombing of Coventry on November 14th 1940. (The Blitz)
The transmitters sent out two parallel signals, one dots and the other dashes. When the plane was on course, between the two signals a steady tone was heard. This later system was called the X-Gerat and was later refined to use four beams.
This system had a very limited life span and the beams were very easy to jam by the RAF and even when the Germans changed frequencies several times during a raid, it was able to be blocked.
The diagram on page 4, explains how the bombing of Coventry was executed to such a great effect, 90% of the bombs falling within 5 kms.
At that time British Bomber Command was flying missions over Germany with an accuracy of less than 50%.
This station was vital for the night bombing of England.
By November 1941 the plans of the station had been obtained by the local Resistance and sent to London.
The later guidance system Y-Gerat, used only one beam was also installed, the aerial being in the field behind the blockhouse.
After the demise of German bombing raids over England Fort Allemande changed its role to that of a radar station it, was bombed several times and craters can still be seen in the fields around the concrete blockhouse.
An early form of radar was also installed here and remains of the pylons are still visible.
The main blockhouse is remarkable as it is the only blockhouse that I have seen an inscription above the main entrance.
The German Eagle is still in situ, although the
Nazi emblem has been defaced by American machine gun fire. The inscription translates as;
“Built by Adolph Hitler in the war against the English”
The only other place I have seen photos of a similar inscription, is at Lorient (submarine pens) which disappeared before the war finished.
Damage to the main building caused by Allied bombs is also still evident You can still see the efforts of the Americans who took this bunker on June 18th 1944.
The main attack coming from the rear, before the building was stormed from the front. It is known that one German died during the assault here.
The main aerial was very large and because the direction of the aerial needed to be set to a high degree of accuracy it was mounted on a circular track, remains of which can be seen in the field behind the blockhouse.
The construction of this radio guidance station was to a very high standard not to be seen elsewhere on the Cotentin Peninsula.
None of the original equipment remains, as most was taken away by the Americans, and the rest removed by local scrap merchants. The main cable from the bunker to the aerial disappeared in 1946, and it would have been worth a small fortune because of the copper content.
One cannot be certain as to the evolving use of the bunker during the war.
The main entrance would have been through the right hand door under the Eagle.
A chicane would have restricted the entrance width.
Room 1) This would have been the living accommodation for the troops stationed here, opposite the officers room..
They were billeted in the village, but would spend long periods on duty here, mostly at night.
A toilet and shower were provided (Room 2).
The shower was a standard feature of most German bunkers as they feared a gas attack.
Room 5) This room has evidence of housing three diesel generators The heat generated by the diesel motors necessitated the use of an air cooling system, which can be seen in the roof space.
The water tank (2 on upper plan) would have been used to supply the radiators of the generators.
Room 4) There would have been large quantities of batteries, needed to give a stable voltage to the radio guidance and radar equipment. The room was tiled so that any acid spillage would not enter the concrete and give off poisonous fumes.
Room 3) Here would have been housed all the transmission equipment to set up the navigation beam, and the later radar.
The transmitters would have also been installed in this room, and again because of the heat of the valves, forced air would have been needed to keep temperatures down.
The X-Gerat beams (Knickebein), as directed over Coventry on the night of 14th November 1940
The bombers flew from Vanne in Brittany, flying north until they flew between the two signals.
This station was identified as Knickebein-Stellung K10 its sister station was at Mount Pincon K8 near Rouen. The headquarters and maintenance station was at Beaumont Hague K9.
The German pilots would have heard the left hand signal first, but on the wrong side of their headset.
On finding the right hand signal they would turn left and would then hear a faint left hand signal, which they would fly towards until they heard both signals at the same level of volume. They were then on course for their target.
A second set of signals were emitted from eastern Europe.
During the early days all the X-Gerat beams came from Mount Couple near Calais, but later when the Y-Gerat system was introduced the intercepting beams came from three different transmitters. Below are listed the Y-Gerat stations, and the beams use.
The first of these cross beams (A) called Rhein, which was transmitted from Cleve in Germany, told the aircraft that they were 50 kms (30 miles) from their target.
On crossing the second beam (B) called Oder transmitted from Julianadorp in the Netherlands, told the aircraft observer presses the button to start the bombing clock.
The distance to the target is now 15 kms (9 miles)
When the aircraft intercepts beam (C) called Elbe, this bean originated from Bredstedt in Northern Germany. On hearing the beam the aircraft observer stops the bombing clock, it is now 5 kms (3 miles) to the target. The second hand continues to sweep and when it is aligned to the other hand, an electrical contact is switched and the bombs are released.
Luftwaffe station K10 Knickenbein FuSAn 721 - Water reservoir
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