Kammhuber line
The Kammhuber Line was a strategic facility for radar-based air defense using the four-poster method by the Wehrmacht Air Force during World War II and, when completed, reached a length of over 1,000 kilometers from northern to southern Europe.
Structure and principle of operation
After the victory over France in the western campaign , Reichsmarschall Hermann Göring appointed Colonel Josef Kammhuber on July 19, 1940 as the commander of the 1st Night Hunting Division , which was in formation , consisting of only one Night Hunting Squadron ( NJG 1 ), a Searchlight Brigade and an Air Intelligence Regiment. A second squadron ( NJG 2 ) followed later . In August 1941 he was "General of the Night Hunt" with command of the XII. Fliegerkorps, to which all night air defense units were subordinated.
Kammhuber developed and organized the interaction of all listening posts, searchlight batteries, anti-aircraft and radar units and night fighters guided from the ground, which until this time had acted largely independently of one another - under separate command and without joint communication - against increasingly incoming Allied bombers. For this purpose, Kammhuber set up a chain of intersecting air defense zones, so-called four - poster beds . The terms Kammhuber-Linie or Kammhuber-Riegel were coined by the Allies and not used by the Germans until the end of the war.
Successes and failures
The Kammhuber Line was initially extremely effective against the few incoming bombers, but lost its effectiveness from mid-1942 to 1943, when the Royal Air Force flew more and more often with hundreds of bombers into the Reich. One reason for this was that only two night fighters could be directed to the enemy per four-poster bed. There were also considerable setbacks, for example the first 1000 bomber attacks on Cologne ( Operation Millennium , May 30/31, 1942), Essen, Bremen , the firestorm in Hamburg ( Operation Gomorrah July / August 1943) and the Use of chaffs that made the four-poster bed method ineffective for months. Therefore, by autumn 1943, the rigid "Kammhuber Line" was made completely flexible, in that night fighters with modernized on-board radar (see Lichtenstein (Radar) ) were led in larger groups to bomber groups and independently went on free night hunting. Even day hunters were also used in night hunting with the help of the flak headlights ( "Wilde Sau" ). The new tactics brought Kammhuber's air defense system new defensive successes until September 1944, until the war-related lack of fuel kept the German night hunt largely on the ground until the surrender in 1945.
realization
Kammhuber's goals were to be achieved by establishing various areas that were to serve to repel Allied attacks. There were three different areas for this: the dark night hunting rooms (Dunaja), the light night hunting rooms (Henaja) and the combined night hunting rooms (Konaja). Combined night hunting rooms were set up around areas requiring special protection. In these konajas, allied attacks were to be fought with the interaction of fighter pilots and flak . Konajas were in action around Kiel (Konaja "Kiebitz"), Hamburg (Konaja "Hummel"), Berlin (Konaja "Bär"), Duisburg (Konaja "Drossel"), Cologne (Konaja "Kolibri"), Bremen (Konaja "Roland "), Darmstadt (Konaja" Badger ") and Munich (Konaja" Mücke "). This defense method, however, led to numerous losses of its own if the shooting success was low and was replaced around the end of 1941 by improved, freer fighting methods ( Wilde Sau , Zahme Sau ).
Since the advance warning time had to be as long as possible for an effective air defense, a system of " Freya " and " Würzburg " devices was set up on the North Sea coast, and later also on the Atlantic coast . Unlike their English counterparts, these were highly complex systems with professionally trained staff who were practically barracked for reasons of confidentiality. The technical progress over England was about seven months in 1942; everything was done to maintain it. However, they failed to recognize that a highly complex and expensive system is a tactically difficult target, but a strategically all the more worthwhile, and so the USAF and the RAF succeeded several times in putting the Kammhuber system out of action for hours to days through targeted tactical attacks put.
The function largely corresponded to modern radar , with a few minor differences:
There were - often spatially separated - systems for passive and systems for active location. The Würzburg-Riese equipment mentioned sent with their 8-meter parabolic mirrors a fan of radar wave cones from was where modulated onto the central cone with a frequency of about 560 MHz, a signal (FM) technique of its own for each sector of this fan beam Frequency had. The Freya systems were assigned to these transmitting stations. A Freya system was set up much more simply, to describe it most accurately, than a dipole antenna. The individual antenna rods were to be connected to the amplifiers in such a way that the radio measurement technician had a search and focus mode available. The Freya system had the great advantage that the data received could be evaluated acoustically. The measurement technician had headphones with which he heard the modulated signal as soon as his antenna picked up the reflection. As a result, no expensive and short-lived equipment such as screens were necessary.
This also includes listening posts and observation units. The Würzburg plants were named "Wolf" (North Friesland), "Languste" (East Friesland), "Lion / Tiger" (West Friesland), "Hering" (West Netherlands), "Hamster" (Belgian / Dutch border area) or "Lori" ( northwestern Lake Constance area). The area around Mannheim had a combined Würzburg / Freya lighting zone, which was code-named "Kranich".
Hunt management
- An enemy aircraft entered the surveillance airspace.
- The signals emitted by the Würzburg giant hit its outer skin and were reflected. Depending on the sector (relative to the transmitting antenna), the tone modulated on the carrier wave was high or low.
- The reflected signal was received by a Freya station. For example, the technician heard a loud signal of the same frequency on the left and a soft signal on the right on his headphones and thus had his antenna pointed a little further to the left. The individual wings of its antenna had their own amplifiers and were connected to the headphones.
- He could now read from the direction of the Freya systems from which direction the signal was coming.
- Now he switched comparison tones to his headphones and was able to use the resulting chords and beats (or the consonance) to determine in which sector his surveillance object was relative to the Würzburg station. From this the position was to be calculated trigonometrically.
- The radio test supervisor reported the position to the air surveillance, which had the signals marked on their tactical board.
- The airspace surveillance should now be noticed if several Freya systems were following the same signal or if a signal changed from the surveillance sector of one system to the sector of another system. It decided which plant then pursued which goal and ordered the remaining plants to monitor the sectors that had become free.
- Then they put the interceptors of the locations that were in question as targets on alert (the pilots sat on the plane ready to take off). These were classic fighter planes with signal paint.
- At the same time, chasers were launched. These were mostly fully camouflaged Bf 110s (repainted variant "C", from May 1942 almost only the G4 in its various versions) and from February 1942 had a passive ("Lichtenstein device", "Rostenthal-halbe" etc.), later also active radar ("Lichtenstein SN" and "SN2", "Neptunanlage" and "Flensburgsystem") and tracked the bombers. The hunters themselves had no navigation facilities. They could only orientate themselves on rivers or other landmarks visible at night.
This is where a second Freya station came into play, chasing the hunter and bringing him to the target by radio. If possible, the fighter was brought up to the bombers against the moonlight so that he could make out the dark silhouette in front of the clouds. Dabei was to eighth out that only a Jäger also a Bomber / Staffel verfolgte, and not stieß a Jäger on one another Jäger.
- If it was possible to roughly estimate which cities could be targeted, the night fighters were instructed accordingly (which made navigation easier), then the anti-aircraft belts were put on alert. They proclaimed a low alarm level for the city (lighting ban, etc.), mostly with an exact time indication of when the bombers were expected to arrive. Once the target was clearly identified, an air raid warning was issued to the affected city, anti-aircraft guns were manned and searchlights were brought into position. The interceptors took off and went to the heights swept by the Freya stations.
- When the bombers got dangerously close to the flak belts of the industrial areas / port facilities, the twin-engine night fighters turned off. Too often they had been the victim of their own flak, despite flares and clear typing. The flak simply shot at any multi-engine airplane. The fighters returned to their locations, were refueled and ammunitioned, and they often launched a second attack against the returning bombers (however, due to their lower load, these had a higher speed and a higher altitude, and also a lower priority).
- The single-engine day twilight fighters took over the aerial combat. These were fast and agile enough to maneuver in approaching bomber squadrons, while their silhouette made them easier to distinguish from the bombers.
See also
literature
- Lars Zimmermann: “Kammhuber Line”. The way to night hunting . Military history. Journal for Historical Education 1/2018, pp. 22–23.
Web links
Individual evidence
- ^ RV Jones: Most secret war. P. 501.