Instead, it was being prepared for the first military electronics reconnaissance in history, twenty-one years before the American U-2 hit the headlines with its crash in Russia.
General Wolfgang Martini, head of the Luftwaffe signals organisation, had for many months been interested to discover whether Britain possessed a workable radar for detecting aircraft. German firms were busy developing such equipment, and his suspicions had been heightened by the appearance of unusual 350-foot-high aerial masts round the south and east coasts of England.
When the first masts had gone up at Orfordness in Suffolk the German Air Force maps labelled them as belonging to a radio-transmitting station. Then Bawdsey showed similar towers and these were followed by others at Dunkirk and Dover in Kent and Canewdon in Essex. By early 1939 masts were up, or in process of erection, from the Isle of Wight to the Orkneys.
Martini urgently required to know the state of British radar, its wavelength and the number of sites operational. The tall masts with their crossed lattice aerials appeared, however, to be unsuited to the wavelengths which German scientists had deemed best for their own secret Freya and Würzburg radars. Accordingly, at a meeting with Göring, Milch and other air force commanders. Martini proposed that twelve airships be made available for high-frequency ‘research’.
At first the assembly was hostile to the idea, but began to show a more helpful attitude as Martini explained his purpose. He could not, he pointed out, use an aeroplane, as it was too small, lacked endurance and could not remain motionless in the air. With an airship he would have all the space necessary, many hours of flying time and the ability to stop and take readings where necessary.
Göring and Milch felt that any production of airships would use up large quantities of materials urgently needed for aircraft. Finally, however, it was agreed that Martini should use the two existing Zeppelins, L.Z.127 and L.Z.130, and if the experiments were successful four more should be ordered.
Work was immediately started on converting one of them into an airborne radio interrogation station. A number of new high-frequency receivers were installed and an aerial array rigged underneath the gondola.
Towards the end of May 1939 preparations were completed. Under cover of night the 776-foot-long airship slipped her moorings at Frankfurt and headed out over the North Sea. Her course stood westwards in the direction of the Bawdsey Research Station in Suffolk where the tall radio-transmitting masts were situated.
General Martini himself was on board for this trial run, which was mainly concerned with testing the receivers. Off Bawdsey, Graf Zeppelin turned north and flew parallel to the British east coast. The operators and technicians in the gondola anxiously waited for some response from the radio receivers, but each set emitted a loud crackling noise and nothing else.
At Canewdon and at Bawdsey the staff were amazed to find the largest ‘blip’ they had ever seen, travelling very slowly across the cathode-ray-tubes.
Fighter Command filter and operations rooms immediately began tracking on the map tables. It became evident that the strange visitor, because of its size and speed, could only be an airship. From its course along the coast it was correctly deduced that some sort of radar interrogation was in progress.
One by one the east coast Chain Home radars picked up Graf Zeppelin as it progressed northwards. Over the Humber estuary the airship transmitted a position report back to Germany. This was picked up by British radio intelligence who informed Fighter Command that the German ‘fix’ was a few miles off the coast of Yorkshire.
At the Bentley Priory operations table this news caused considerable amusement, as Graf Zeppelin’s correct position had just been established, in cloud, over Hull itself—well inland. Air Marshal Pretty (then a flight-lieutenant on radar duty at Fighter Command) recalls that ‘We were sorely tempted to radio a correction message to the airship but this would have revealed we were actually seeing her position on radar, so we kept silent.’
Off the north-east coast Graf Zeppelin turned for home, having picked up nothing but an appalling noise in the receivers. General Martini still did not know whether British radar was operational.
It was assumed that the interference was due to an installation defect and the reflections from the airship’s envelope. Modifications were made to the sets and to the aerial and further trial runs were made over Germany.
During one of these the engineer responsible for the aerial, Dr. Sailer, slipped on the ladder between the gondola and the special basket holding the aerial. The altitude was too low for his parachute to open fully, and he fell into a forest, severely injuring his spine. This incident gave rise to later ill-founded rumours of a photographer in the under-basket with a special long-focus lens to record the radar masts on film.
Finally, all was ready for a second run up the east coast. This time Martini was not on board and the senior officer was Oberstleutnant Gosewisch, now Generalmajor retired and regional director of civil defence in Bonn.
At midnight on Wednesday, August 2nd, 1939, the Graf Zeppelin again slipped her moorings and steered for the North Sea. Her instructions were to keep close to Britain, but maintaining about fifteen miles distance from the shore. The wave-length strength and position of all high-frequency emissions was to be noted.
The night had been chosen for its poor weather and low cloud which gave adequate protection against sighting from the land. During the morning of August 3rd the airship came abreast of Bawdsey and turned north towards the Wash.
Once again no transmissions were detected and more faults developed in the receivers. Curiously, British radar did not pick up the airship, although the stations were operating.
It was not until three o’clock on the 3rd that the Graf Zeppelin was located visually off the coast of Kincardineshire proceeding north towards Scapa Flow. Half an hour later another sighting was obtained by coastguards at Collieston, Aberdeenshire. Two auxiliary air force fighters took off from Dyce, and identified the airship, which was well outside the three-mile limit.
The last sighting was by the lighthouse-keeper at Girdleness who was surprised to see the airship overhead at below 1,000 feet. Graf Zeppelin cruised on up to the Scapa Flow base, catching glimpses of British warships through the clouds. In the early evening she turned back to Germany—empty-handed. No high-frequency signals had been detected.
The London Daily Telegraph was quick to report the airship’s appearance over the islands. At 4 o’clock in the morning Gosewisch had retired to bed after the long flight, but was promptly awakened by General Jeshonnek, air force chief of general staff. The General wanted to know whether Graf Zeppelin had in fact crossed the British coast as the newspaper suggested. Gosewisch denied that this had occurred.
On the following day, August 4th, a highly amusing official communiqué was issued concerning the reconnaissance flight. Berlin denied that the Graf Zeppelin had intentionally left the Reich or had approached the coast of England. The statement went on: ‘The airship cannot leave Germany without special permission. There can be no question of an intention to fly over near British territory. There have, however, been severe storms during the last day or two and it is possible that the airship could have been blown off her course over the North Sea.’ A few days later a further flight was carried out, but again with no results.
So ended the Zeppelin’s career in radar survey. Within a month war had broken out, and afterwards both Graf Zeppelin 1 and Graf Zeppelin 2 were destroyed in the sheds at Frankfurt.
Neither side realised that the opening round of the air war against Britain had been fought and lost by Germany.
If the airship’s equipment had worked properly in the first place there would doubtless have been many more reconnaissance flights. Radar would then have merited serious study by the Luftwaffe Command staff and intelligence departments.
This in turn would have produced new German tactics for the Battle of Britain, a sustained assault on the coastal radar stations and the employment of airborne jamming devices. Such steps would have deprived the R.A.F. of its long-range-warning cover and the outcome of the Battle of Britain might have been very different.
As it was, the German Air Force made no efforts to investigate the radar chain or the fighter-control system to which it was linked. Bombing of radar stations was abandoned early in the battle. The German High Command chose to ignore the advent of science in warfare.