The day began badly for these long-range raiders. An error in navigation made their track so near to the feint attack that they were picked up on the British radar as one large formation. The defences were alerted.

The radar operators of this northern part of England's chain, lacking the experience of their 11 Group colleagues, estimated the raid at about thirty aircraft. At 12:15 p.m. the Controller scrambled 72 Squadron at Acklington in Northumberland. Its leader was at 18,000 feet, far out over the sea, looking for thirty German raiders, when he made contact. As well as two Gruppen of KG 26 Heinkel He 111s, there was a whole Gruppe of Bf 110s: about a hundred 'bandits' in all.

The twelve RAF fighters were 3,000 feet higher than the raid, and the RAF formation leader continued out to sea, in order to turn and attack out of the sun. Over the radio-telephone one of his pilots asked him, "Haven't you seen them?"

In a reply that was to become famous throughout the whole of Fighter Command, the leader said, "Of course I've seen the b-b-b-b-bastards. I'm trying to w-w-w-work out what to do."

No. 72 Squadron split: one half to take the Bf 110 fighters and the other to attack the Heinkels. The Gruppen-kommandeur of the Bf 110s was leading the fighter escort. He tried to jettison his long-range tank. These clumsy tanks were notoriously unreliable and this one did not fall away before a bullet touched off the vapour. His Bf 110 exploded like a bomb. Some of the Bf 110s formed a defensive circle, in which the tremendous forward-facing firepower could protect a neighbour's defenceless tail. For this trip made without gunners the circle was the only expedient.

Some Heinkels jettisoned their bombs and changed course towards patches of cloud. But with dogged determination most of the bomber crews stuck to their briefing, closing on the coastal towns despite repeated fighter attacks.

Courage of another sort was shown by the 13 Group Controller, who judged (rightly) that this was the entire Luftwaffe effort against his Group. With unprecedented boldness — for the air war in the south had predictable lines of thrust — squadrons from as far north as Drem in Scotland and as far south as Catterick in Yorkshire were vectored on to the German raid. These daring tactics decimated Lцwen-Geschwader and their escort. Fifteen German aircraft were shot down, for a loss of only one RAF fighter.

The southern prong of the attack across the North Sea was made by Junkers Ju 88 bombers of KG 30, the Adler-Geschwader. These were among the newest of the Luftwaffe's aircraft. Their performance had persuaded Stumpff — commander of Air Fleet 5—to let them go unescorted (and so give his Bf 110s to the Heinkels). To provide protection, a few of the Ju 88s had been specially modified with cannons on the nose.

This attack, from Aalborg, Denmark, made landfall in 12 Group, whose commander, Air Vice-Marshal Trafford Leigh-Mallory, the plump, neatly dressed protege of Dowding, had spent most of his career in army-cooperation flying. He had been criticizing the way Park, commander of 11 Group, was handling the Battle, arguing that larger RAF fighter formations would be far more effective against the German raids. More and more he blamed Dowding, too, for not ordering Park to adopt these 'big-wing' tactics.

So it is interesting to note that while Air Vice-Marshall Richard Saul, of 13 Group, had boldly flown squadrons from as far north as Drem, Air Vice-Marshal Leigh-Mallory was nothing less than timid in his reaction. There were no 'big wings' deployed here. The attacked sector used only its own squadrons. Twelve Spitfires of 616 Squadron and six Hurricanes of 73 Squadron intercepted the Ju 88s. The Adler-Geschwader pressed on bravely to bomb the RAF station at Driffield, Yorkshire. They destroyed ten Whitley bombers on the ground. However seven of the Junkers Ju 88s were shot down and three more made crash landings in Denmark, Germany, and Holland.

Even considering the RAF bombers destroyed at Driffield, the Germans paid a heavy price. Of Air Fleet 5's raiding force, nearly 20 per cent had been lost. It was a disappointment to the Luftwaffe strategists. Clearly the northern Fighter Groups had not been depleted to reinforce 11 Group. It also proved that German bomber formations could not operate without (single-seat) fighter escort.

The single-seat fighter achieved paramount importance after this day's fighting. Gone were the theories of the Schnellbomber that outpaced its pursuit. >From this day it was evident that any raid must be accompanied by aircraft as good as those that the defence used.

Now the Luftwaffe could go in strength only where their Bf 109s could go: and that meant a small segment of southeast England. This in turn provided Dowding with a possible last-ditch strategy of putting all his fighters on airfields beyond Bf 109 range. From there, if need be, they would still be able to fight the raiders from unbombed airfields.

And yet another tribute to the single-seat fighter was emerging from the statistics. The Luftwaffe bombing formations could only escape morale-shattering losses by providing two fighters for every bomber in its formations. On this day, for instance, the Germans flew 1,786 sorties, of which only 520 were bombing sorties. So nearly half the Air Fleet's available bombers had remained unused because of the lack of fighter escort.

In the south, Air Fleets 2 and 3 used the Bf 109 as usual, but they could not prevent serious casualties among the more vulnerable aircraft types, for instance the Ju 88 and Bf 110. The raiders did considerable damage at the airfields, upon which their attacks concentrated. However they were still attacking many airfields unconnected with Fighter Command, and tactically the most damage was done by some wild misses that severed power lines and the put radar stations out of action.

In fighting that ranged from Scotland to Devon the RAF lost thirty-four fighters in the air, with another sixteen RAF aircraft lost on the airfields attacked. The Luftwaffe lost about seventy-five aircraft (although this still disputed, and Hans Ring of the German Fighter Pilot Association says fifty-five would be more accurate). Whatever the true losses, soon the Luftwaffe began to refer to this day as der schwarze Donnerstag: black Thursday.

Meanwhile the propaganda services performed with gusto. The Germans claimed 101 victories and the RAF an epic 182.

It was at Göring's top-level conference of Air Fleet and Fliegerkorps commanders that the most far-reaching events took place. Göring decreed that Luftwaffe officer air-crew casualties were now so severe that not more than one officer must fly in each aircraft, and the Stukas must have no less than three fighters each for protection. He added, "It is doubtful whether there is any point in continuing the attacks on radar sites, in view of the fact that not one of those attacked has so far been put out of action."

It was one of the greatest errors of the war.

The pressure continued. After the 1,786 sorties the Air Fleets flew on 'black Thursday', they flew another 1,700 the next day and night.

In spite of Göring's order, the radar station at Ventnor was attacked again. It was only just back in operation after the damage done to it by the 12 August bombing. This time the Ju 87s did enough damage to put the installation off the air for seven days. A mobile unit was brought up to Bembridge but its performance was so poor that its only value was in persuading the Luftwaffe that no gap existed.

A demonstration of the Luftwaffe's tactical abilities was given that evening when two Junkers Ju 88s penetrated as far as Brize Norton airfield near Oxford. The route had been chosen and timed so that previous air fighting caused the RAF fighters to be back on the ground rearming and refuelling. Choosing their moment nicely, the Germans came into the circuit as if preparing to land. They even lowered their wheels, in the hope of being mistaken for Blenheims.