The Royal Navy came to the RAF’s assistance by providing a chain of small craft sailing 3 miles apart from each other 7 miles from the French coast, each with observers on board. Pilots would be warned of flying bombs on their way by the observers firing off star shells or signal rockets. However, this system was not fully in place until the main attack ended.
Running commentary from radar stations and Royal Observer Corps Centres was used for interception over land with various devices such as signal rockets, searchlight beams and star shells to warn the patrolling pilots of approaching flying bombs. This system, however, had a weakness, which was that several pilots would go after the same flying bomb, as we shall see later in the book, leaving other bombs to slip through unmolested. The absence of low-looking radar over land at that time made close control very difficult.
The line from Cuckmere Haven and St Margaret’s Bay was the area where most of the flying bombs crossed in from the Channel. The distance from the coast to the gun belt was about 30 miles, which the flying bombs crossed in five minutes. Pilots patrolling over land then had five minutes to select their targets, get in range and shoot them down before entering the gun belt. Even if pilots did enter the gun belt in pursuit of a flying bomb they only had an extra minute or so before the V1 would reach the balloon barrage and the pilot would then have to break off the chase.
Sir Roderick wrote:
There was rarely time for a stern chase unless the pursuer started with a substantial advantage in height. The most effective method was to fly on roughly the same course as an approaching bomb, allow it to draw level, and fire deflection shots as it passed, being careful not to fire when it was closer than 200 yards lest it should explode in the air and blow up the attacker.
For a fighter flying directly behind a flying bomb the hot gasses pouring from the V1’s jet engine made steady aim difficult so according to Sir Roderick short bursts and frequent course and aiming corrections were necessary. Several bursts were usually required to inflict enough damage to explode the bomb in the air or send it crashing down into the sea or into the ground.
If the fighters had a difficult task in destroying the flying bombs so did the guns. In theory, robot aircraft should have made ideal targets for the anti-aircraft guns as they flew on a predictable course and could not dodge and weave as ordinary enemy aircraft would. This advantage, however, was outweighed by the speed and height at which the flying bombs flew. They were too fast and too high to make good targets for the light AA guns and for the heavy AA guns they were too low and crossed the field of vision too quickly for the radar to be used.
By replacing the heavy mobile guns with static guns that could be electrically elevated and traversed these problems were minimised but the static guns needed concrete emplacements, which took time to install. A steel mattress, used instead of the concrete emplacements, was found to be a much quicker solution and the task of replacing the mobile guns with static guns mounted on these steel mattresses began at the end of June 1944.
General Pile decided to move the radar sets from the valleys, where they had been originally placed because of the worry about jamming by the enemy, to more exposed higher ground where the contours of the land caused less interference. Successive bombing campaigns had, according to Sir Roderick Hill, deprived the Germans of the ability to jam the radar sets of the heavy guns so moving them to higher exposed ground proved less of a risk.
Also, General Pile decided to move the light AA guns from the searchlight sites to concentrate them in front of the heavy gun belt. By linking the lighter guns to the radar sets of the heavy guns they could fire at unseen targets as well as visual targets.
Also, the American SCR 584 radar sets and predictors began arriving towards the end of June, which contributed heavily towards the success of the anti-aircraft guns. A vigorous training programme was set up before this new equipment could be put into action.
As far as the balloon barrage was concerned sufficient density was needed for successful operations against flying bombs, but despite this bombs were still slipping through.
The double parachute links used to arm the cables in normal balloon barrages had not been designed to cope with aircraft travelling faster than 300 mph. During the first few days of the attack the cables weren’t armed but by 21 June all the cables had been armed.
To prevent V1s from getting caught in the barrage and going down in built-up areas the barrage itself was slightly adjusted. At the same time the decision to keep the balloons up all the time no matter what the weather was dropped. However, Sir Roderick states in his report that ‘in order that our pilots should not lose their lives by colliding with the barrage we perpetrated a pious fraud on them by allowing them to believe the balloons would fly continuously.’
We have seen the practical problems facing the various arms of defence during the battle of the flying bombs but the biggest problem of all facing Sir Roderick and his staff was the degree of co-operation between the guns and the fighters. Against ordinary aircraft a working solution had been found between the two rival arms. But against the flying bomb a host of new difficulties presented themselves. ‘It was sometimes hard for a pilot to realise he was approaching the gun belt in time to avoid infringing the rule against entering it,’ Sir Roderick wrote. At the same time, the gunners could be blasting away at a flying bomb without realising that a fighter had legitimately entered the gun belt in pursuit of the same flying bomb. The guns would go on firing.
The gun crews on the coast had an even more difficult task because they bore the onus of ensuring that there were no fighters around before they opened fire. ‘When the attention of the gunners was concentrated on their targets,’ Sir Roderick wrote, ‘it was only too easy for a fighter travelling at six miles a minute to enter the field of fire.’
On several occasions the fighters infringed the gun belt and there were many unintentional engagements by the anti-aircraft guns on the fighters, especially in middling weather when both guns and fighters were operating. ‘Charges and counter-charges mounted,’ Sir Roderick stated. ‘I began to sense a rising feeling of deep mistrust between the pilots and the gunners.’
If things didn’t change the situation would get worse. Sir Roderick continued:
To all appearances the machine was growing more efficient. But this improvement brought me scanty satisfaction. I knew the point would soon be reached at which this friction would become the limiting factor and no further improvement would be possible.
Losing the spirit of co-operation between gun crews and pilots that had been built up over the years could only lead to the efficiency of the defences sharply declining.
Sir Roderick’s solution to the problem was to give the fighters and the AA guns the freedom to work within their own spheres of operation. On 10 July he gave the order for the fighters not to enter the gun belt under any circumstances after 17 July. All the guns were then to be moved inside the belt so they could also operate within their own area of operation, creating a clear-cut situation. Giving the gunners a free hand in their own territory also meant that when they were not in action they could be training but the change reduced the area of operation for the fighters.
Sir Roderick wrote:
To make this sacrifice clear to the pilots I instructed my Deputy Senior Air Staff Officer, Air Commodore G.H. Ambler, C.B.E., A.F.C. to prepare an explanation to be circulated to lower formations. At this stage no question of changing the geographical position of the gun belt had been raised.
But as we shall see there were strong arguments for moving the gun belt, principally put forward by Air Commodore Ambler. In the February Diver plan the guns had been placed in the North Downs to avoid the jamming of their radar by the Germans, which at that time was a very real threat. However, once the landings in Normandy took place successful bombing of enemy radar and radio stations had removed the jamming threat altogether.
With the jamming threat gone there was, by the middle of July, no need for the guns and their radar to be hidden in the Downs if they could be moved to a much better position. The idea was to move all the guns to the coast. This had some definite advantages. To start with the gunners could see their targets better and the effect of ground echoes on their radar was reduced to a minimum. But perhaps, most importantly, they could now use proximity fuses on their shells that they could not have used inland because of the danger to civilian life and property. Also, the majority of the bombs the guns brought down, if they were on the coast, would now fall harmlessly into the sea.
The disadvantage of moving the guns to the coast was that there would now be three operational areas, one for the guns and two for the fighters – in front of the coastal gun belt and behind it. This would also limit the effectiveness of the fighters. The move to the coast made the guns much more effective and the fighters less so.
Sir Roderick wrote:
Up till then the fighters had been by far the most successful weapon against flying bombs. Out of 1,192 bombs which had been destroyed or brought down up to sunrise of the 13th July, they had accounted for 883. No move which was to impair their effectiveness was to be undertaken lightly.
Interception over sea and interception over land had different sets of procedures and difficulties so the problem of having three different spheres of operation was not as bad as they first thought.
Air Commodore Ambler took on board the need for the guns to be put into one place but not on the Downs. On the morning of 13 July Ambler presented Sir Roderick with a formal paper detailing the advantages of moving the guns to the coast. He convinced Sir Roderick that the tactical theory behind the redeployment was sound. Sir Roderick knew a decision of either accepting the proposal or rejecting it had to be made that day. He called for a conference late that afternoon but spent the morning mulling over the proposal.
At the conference, the plan for moving the guns to the coast was endorsed by everyone present and adopted.
Sir Roderick took the responsibility of the success or failure of the scheme on his own shoulders and immediately gave instructions for the preparations of moving the guns to the coast to begin right away. ‘During the following week vehicles of Anti-Aircraft Command travelled an aggregate distance of two-and-three quarter million miles in consequence of this decision,’ he wrote. Ammunition and stores, weighing as much as two battleships, the guns themselves and 23,000 men and women were moved to the coast and enough telephone cable was laid that would stretch from London to New York.
By dawn of 17 July the heavy guns were in action and two days later so were the light guns.
Sir Roderick was fully aware of the risks he was taking and the detrimental effect the move would have on the effectiveness of the fighters. If things went wrong and the performance of the guns didn’t improve he alone would be responsible for that disaster. The Air Ministry were not pleased.
They informed him formally a few days later that he should not have ordered a major re-deployment of the guns without consultation and approval from them.
However, within a few weeks Sir Roderick was vindicated as the number of flying bombs shot down by the guns dramatically increased. This increase showed how sound the decision had been that had come after Air Commodore Ambler’s proposal. The Air Ministry sent a letter of congratulations to Sir Roderick’s command at the close of the main attack.