Aboard the German ships everything was peaceful. The weather was still fine and there was no sign of the British. The only problem was exact navigation. One of the officers said jokingly to Giessler, "This could well be an instruction trip for quartermasters." It was so quiet that the crews began to worry. Why were the British apparently doing nothing? Was it all a dreadful trap?
They did not know that all morning General Martini's electronic interference had almost completely deceived the British. Two specially equipped Heinkel 111 aircraft had left Evreux, north of Paris, in complete darkness in advance of the fighters. Each had jamming equipment which could simulate twenty-five aeroplanes. Over the Channel, the recognizable search pulses of the British equipment were soon received on their cathode-ray tubes. When they switched on their jammers, British radar impulses wavered, altered their synchronized position and their amplitude, or changed occasionally to another frequency. The planes could follow these changes without difficulty.
Both jamming planes flew parallel to the English coast to give the British radar direction finders (RDFs) the impression that German planes were circling there. This was to distract attention from the night-fighters circling over the battleships.
As the German warships passed the mouth of the Seine the British radar stations, holding on to die deceptive impulses, did not detect them.
Martini ordered his land-jamming installations strung along the French coast not to be switched on until 9 a.m. All known British RDF transmitters were each monitored by German groups, to which they were tuned in exactly. These stations knew precisely the behaviour of "their" British transmitters.
They soon observed that several British transmitters began to alter theiir frequency in an attempt to avoid the jamming. Two switched off completely, then suddenly a new station between Eastbourne and Dover, which had not been observed for several months, was tuned in. This was also jammed.
This was the first engagement in pure high-frequency war. Martini's plan was succeeding — but not completely. Although the British radar operators were confused by these counter-measures, at the same time the German computing centre at Boulogne picked up transmitters with seven to eight centimetre wavelengths. These were the new K-sets for which the Germans had no jammers.
British radar station K-set, located at Swingate, was beginning to report that several aeroplanes were circling over a group of ships sailing at a speed of about twenty-five knots. As a result of this report, and the accumulation of evidence about radar-jamming, the British began at last to suspect that there might be something special going on in the Channel. It remained a suspicion. They still had no confirmation.
At 8:25 a.m., when Wing-Cdr. M. Jarvis, Senior Controller of the radar filter room at Fighter Command headquarters at Stanmore, West of London, came on duty, a number of plots of. German aircraft were coming in from the British south coast radar network. The operations table at Fighter Command seemed to show them circling in a small area. Between 8:25 a.m. and 9:59 a.m., four plots appeared intermittently. Three seemed to indicate the presence of a single German aircraft — the fourth possibly two German aircraft.
No one took much notice. Plots like these were common over the Channel. They usually indicated aircraft circling over coastal shipping, aircraft testing their guns or air-sea rescue planes.
At 8:24 a.m., Swingate RAF radar station located several small groups of German aircraft, flying at 3,000 feet, twenty-five miles to the north of Le Havre. They plotted them until 9:20 a.m., then again from 9:47 a.m. to 9:59 a.m. The plotters diagnosed the "blips" as aircraft circling over ships steaming at about twenty-five knots.
They were Colonel Galland's early duty fighters, which had joined the ships at 7:50 a.m. If the pilots had obeyed orders Beachy Head would not have picked up their plots. Their orders called for very low flying to avoid radar detection. But it was not dawn until just after 8 a.m. on that foggy winter's morning, so the German fighters did not risk much wave-hopping — and Beachy Head detected them.
At 8:45 a.m. — twenty minutes after the first "blips" were reported — Fighter Command talked to 11 Group about them. Jarvis was particularly interested in the Swingate plot, which showed a number of aircraft circling somewhere off Le Havre. He informed 11 Group, whose job was the protection of London and the south coast, that this was probably German aircraft escorting coastal shipping. There were also reports of interference, but as this had been experienced frequently recently he paid little attention to it.
When he discussed the radar reports with the duty controller of 11 Group at Hornchurch, they both agreed that there was "Some sort of air-sea rescue operation going on out there."
At 8:35 a.m. Vice-Admiral Bertram Ramsay, commanding the Channel from Dover Castle, "stood down" his coastal forces from the critical before-dawn alert.
At 9:00 a.m. fourteen Coastal Command Beaufort torpedo bombers of 42 Squadron took off from Leuchars, heading for Coltishall in East Anglia. It was a precautionary flight, based on Coastal Command's estimate of a possible Channel breakout. They had first received the order to fly south four days before, but their flight had been delayed by blizzards and "administrative difficulties."
No one was seriously alarmed. There was no jamming yet. This was because Doctor Von Scholz, in charge of General Martini's operation, was obeying the most stringent orders against any jamming until after 9:00 a.m., in case it gave the British a clue too early. This order was rigidly observed.
While the filter room at RAF Fighter Command Stanmore analysed these "blips," a number of radar stations began to report intense jamming. This was Martini's plan coming into action. It continued intermittently for fifty minutes. Even when it became continuous English Channel radar stations still reported it as "interference."
The filter room at Fighter Command started receiving their reports from 9:25 onwards. During the next half-hour they discussed them with 11 Group. At 10:00 a.m., Jarvis, who had been receiving more continual plots of circling aircraft, decided that surface vessels were making their way up the Channel. Once more 11 Group dismissed the radar plot as "possibly German aircraft exercising."
Yet Biggin Hill, one of the fighter stations heavily involved in the battle, was not deceived. When Sq. Ldr. Bill Igoe, the Controller, came on duty he noticed a series of circular radar plots moving out from the Cherbourg peninsula. It was Galland's fighters moving into position. The speed check he took showed the bigger "blips" were moving at twenty-five knots. This meant that the aircraft were covering some shipping. As a convoy could not move at twenty-five knots, he concluded that they must be the Scharnhorst and Gneisenau.
This was the first evidence to suggest that the battleships were out. As the plots continued up the Channel, he rang 11 Group shortly after 8 a.m. and passed the alarm saying, "I think it's 'Fuller!' " He had the impression no one at the other end knew what the code-word meant. Uncertain of 11 Group's reaction, Igoe, on his own initiative, asked Oxspring at Hawkinge to take oft" to make a check. For even if it turned out to be a false alarm, it would be a good tactical exercise.
Shortly after 10 o'clock, just as the German night-fighters above the ships were handing over to the ME. 109s, Igoe phoned Sq. Ldr. Oxspring at Hawkinge and said, "Look, Bobby, radar is showing a lot of German fighters in the Somme estuary. They seem to be going round in circles. At first we thought they were forming up for a sweep, but they still keep circling round. I don't understand it. It looks as if they are protecting some shipping. Go and have a look. But be damned careful as there are a lot of Huns about."