On the night of 12/13 June 1944 shortly after midnight German long-range guns opened up and sent shells across the Channel. Eight fell on Maidstone, one at Otham and twenty-four at Folkestone. The effect of this bombardment was the belief for some people that the Germans were using some sort of new weapon that would create an atmosphere of uncertainty and rumour.
On the same night an Me 410 flew over London and was shot down by AA fire near Barking.
Then at 0400 hrs the shelling stopped. A few minutes later an observer of the Royal Observer Corps (ROC) in Kent spotted an aircraft passing overhead that made a ‘swishing sound’ and had a bright glow coming from the rear. The ROC had been trained to recognise the flying bomb and so following his training he shouted ‘Diver’ as the flying bomb shot by, heading over the North Downs until its engine cut out and it crashed exploding on the ground at Swanscombe near Gravesend at 0418 hrs. The observer said the flying bomb made a sound similar to a model T Ford going up a hill.
In the next few hours three more flying bombs came over and crashed at Cuckfield, Bethnal Green and Sevenoaks. In this first wave of attacks, six people were killed at Bethnal Green and nine injured.
Then the attack stopped, leading Air Marshal Roderick Hill to conclude that such a small effort didn’t justify the major redeployment of anti-aircraft defences as his revised plan stated. He therefore ordered that the plan should not be put into place until they knew what was going to happen. The V1s were to be engaged in the same way as ordinary aircraft with the existing defences in place. At the same, time several bombing raids on the supply sites for the new modified launching sites took place on 13, 14 and 15 June.
Despite these bombing raids the flying bomb attack began in earnest on the evening of 15 June and over the next twenty-four hours 200 flying bombs were launched against the south of England. ‘144 crossed the coasts of Kent and Sussex,’ Sir Roderick wrote. ‘73 reached Greater London.’
The following morning a very different situation from 13 June stared the authorities in the face. Sir Roderick now felt that the revised Diver plan should be implemented as quickly as possible and this was agreed by the Chiefs of Staff. At a staff conference that afternoon attended by the Prime Minister and Minister of Defence the decision to redeploy the gun, searchlight and balloon defences to counter the attacks was taken. Also, it was decided that the guns inside and outside the London defensive area should continue to engage the flying bombs.
Sir Roderick gave the order for the Diver plan to be implemented that day and in the early hours of 17 June the first of the AA regiments began to move. Originally, the plan called for deployment of all the defences to take twenty-five days and the Air Ministry had expected to provide a month’s warning. ‘In the event we received no warning at all,’ Sir Roderick wrote. ‘Apart from that provided by the Germans themselves on the 13th of June.’ The original timetable was thrown out and the deployment took only five days after the order had been given.
All the while the flying bombs were coming over at rate of about 100 per day. The fighters were destroying 30 per cent of that number while the rest of the defences were destroying another 8 to 10 per cent, but more than half were getting through to London. The scale of the attack showed that the static defences of guns, searchlights and balloons needed reinforcing. By 28 June 363 heavy guns and 522 light guns were in action with further light guns from the Royal Air Force Regiment, anti-aircraft tanks from the Royal Armoured Corps and rocket projectors in action against the doodlebugs.
Fighters of No. 11 Group (the Tempest V, Spitfire XIV, Spitfire XII, Spitfire IX and Mosquito night fighters) had been in action since the main attack began. On 16 June Sir Roderick defined their area of engagement as patrolling the Channel and the land between the coast and the southern limit of the gun belt. He prohibited them from passing over the gun belt unless they were actually chasing a V1. In good weather, the fighters were much more successful than the guns because they were hampered by the fact that the V1s were not flying at 6,000 to 7,000 feet as the Air Ministry had previously estimated but between 1,500 to 3,000 feet, making it much more difficult for the gunners to shoot them down.
During bad weather, the guns became the first line of defence and the most effective way of bringing down the V1s. Also, in good weather the guns were to remain silent to give the fighters complete freedom of the air, whereas when the weather was bad the reverse took place, the guns had complete freedom of action and the fighters remained on the ground. When the weather allowed both guns and fighters to operate then the fighters operated in front of the gun belt and only flew into the gun belt when chasing a V1, otherwise the guns inside the gun belt could fire with impunity up to 8,000 feet. However, the light AA guns linked into the communications network were instructed to open fire on targets they could see provided no fighters were in the vicinity.
Sir Roderick drew up these rules of engagement to ensure that there was no interference between the fighters and the guns. He issued these rules of engagement on 26 June 1944 but they did not entirely achieve his aim.
The Allied air forces responsible for offensive countermeasures against the flying bomb began a series of bombing raids on the new launching sites in the first two weeks of the attacks and these raids destroyed several. But they did not reduce the scale of the flying bomb attacks on England. Sir Roderick wrote:
The factor limiting the German effort was not the number of sites available, but something else – most probably the rate at which the flying bombs could be supplied to the launching sites.
The efforts of the strategic and tactical air forces against the flying bomb launching sites were seen as harassing the launch crews to lower their efficiency. ‘It was arguable that the attacks on the “modified sites” amounted to locking the stable door after the horse had been stolen and were a waste of effort,’ Sir Roderick wrote. After the war was over the Germans admitted that the bombing of the new launching sites made no difference to them at all.
Intelligence reports showed that the key supply sites for the flying bombs were likely to be underground storage depots in the limestone quarries of the Oise valley as well as an abandoned railway tunnel in Champagne. These sites were duly pounded by bombs and fighter-bombers, which resulted in a noticeable decrease in the number of flying bomb attacks.
The Germans found alternative channels of supply and the scale of the flying bomb attacks increased. It became obvious to Sir Roderick and his staff that the efforts of the Allied air forces would not be able to stop the flying bombs completely. The land forces in France by the end of June had not yet broken out and were still in the lodgement areas, which meant that the capture of the launching sites was not around the corner. ‘The preservation of thousands of lives, much valuable property and productive capacity would turn on our ability to provide an effective defence for London,’ Sir Roderick wrote.
Up until the end of the first week in July roughly 100 flying bombs a day were still coming over. This number dropped to around seventy a day for the next ten days. This was partly due to a period of very good weather. The Germans saved their biggest efforts for days when the weather was so bad that effective fighter defences could not be mounted. But, it may also have been due to a successful night attack on the main storage depot on 7 July by Bomber Command.
During the five-week period that ended on 15 July 1944 almost 3,000 V1s came within the defences and a tenth of those were shot down into the sea by fighters, with the guns knocking down a few more into the sea as well. Of the remaining 2,500 or so that crossed the coast, fighters, guns and balloons accounted for roughly half over land, with the fighters claiming ten and the guns four for every one the balloons destroyed.
However, the overall average since the attacks began up until the 15 July was forty bombs a day getting through to London alone. ‘London had endured heavier bombing than this in 1940,’ Sir Roderick stated. ‘But for various reasons an intermittent drizzle of malignant robots seemed harder to bear than the storm and thunder of the “Blitz”.’
Between 13 June and 15 July 1944 3,000 people had been killed, more than 10,000 seriously injured and 13,000 homes irreparably damaged.
Since the beginning of the attacks the performance of the defences had steadily increased. In the first two weeks of July the fighters had performed particularly well but Sir Roderick believed they had reached the zenith of their performance with the existing methods. He believed that unless changes were made the performance of the defences would steadily decline.
To get a more intimate knowledge of the special problems of the arms involved he decided early on to share in the fighter operations as a pilot and used various aircraft to do it. His personal experience convinced him that the first problem the fighter pilots faced was the speed of the V1. Sir Roderick stated:
Most of the bombs seem to have left the launching site at about 200 mph. Their speed increased throughout their flight, reaching about 340 mph at the English coast and 400 mph or thereabouts over London.
The fastest aircraft Sir Roderick had at his disposal early in the attacks were a wing of Tempests and a wing of Spitfire XIVs. But as they couldn’t be everywhere at once he borrowed a wing of Mustang IIIs from the Second Tactical Air Force. These proved to be ‘very fast at the height at which the bombs flew and made a valuable contribution to the improved results achieved by the fighters after the first week in July’.
By 15 July, Sir Roderick had a total of thirteen single-engine fighter squadrons and nine Mosquito squadrons flying against the flying bombs. Six of those squadrons did other work, alternating between flying bomb duties and operations over the beachhead in Normandy.
To get as much speed as possible from the fighters used exclusively against the V1s ground crews were ordered to strip all their armour and all unnecessary external fittings, remove their paint and polish their external surfaces. The engines were also modified so they could use 150-octane fuel with a higher than usual boost. These changes managed to provide an extra 30 mph in speed for most of the fighters.
But they only had a small advantage of speed over the flying bomb according to Sir Roderick Hill. He states in his report that:
… they did have a margin. Even so it was no more than a fractional superiority hence the problem was essentially one of time and space.
For interceptions over the sea we used a method of close control from radar stations on the coast, or alternatively a method of running commentary. At best the radar chain could give about six minutes warning before the flying bomb reached the coast; but in practice the time available to [the] fighter was always less than this.
The reason was that the modified fighters could not be used closer to the French coast where they could be intercepted by German fighters. Their lack of armour would have meant greater risks for the pilots and increased losses for the RAF.