2.3 Battle of Britain - 10/7/40 to 31/10/40 2.3.1 Countermeasures Against Knickebein In order to counter Knickebein the radio beam navigation and bombing aid then being employed by the German night bombers, a number of 'Aspirin' jamming transmitters under the control of the Air Ministry were installed in the West. The first temporary equipment became operational at Upavon, in Wiltshire, on July 10th, followed by other installations at Glastonbury Police Station, Temple Combe, Beacon Hill near Salisbury, and Shipham. The countermeasures subsequently proved very successful and deprived the Luftwaffe of a simple and efficient bombing aid, the only one available to the whole bomber fleet. 2.3.2 No.10 (Fighter) Group Takes Shape: July 1940 Throughout July improvements were also made to the fighter defences of the West Country, and as part of these Warmwell airfield, near Dorchester, opened as forward operating base for Middle Wallop. A major reorganisation then took place within Fighter Command, the Filton Sector becoming part of a new No.10 (Fighter) Group, which came into being on July 8th. The establishment of the Group had in fact been contemplated before the war and construction work on the new Headquarters at Rudloe Manor, Box, near Bath, had started in February 1940. From here it was to oversee the defence of the whole of South West England and South Wales during the ensuing conflict, and as part of the scheme two new Sector Stations were quickly established within its area, at Pembrey and St.Eval. Pembrey was replaced by a purpose built fighter airfield at nearby Fairwood Common in June 1941, while during the course of the war Exeter, which did not become a separate Sector until early 1941, also operated Culmhead (Church Stanton) and Winkleigh as satellites. When No.10 Group first went into action its commander had four squadrons to divide between his three Sectors, and for some months afterwards he continued to lack any purpose-built Sector Headquarters or sufficiently well equipped aerodromes in suitable locations. Nevertheless the situation was slowly improving and by mid-July another Hurricane squadron, No.87, newly arrived at Exeter, had joined No.92 in night deployment at Hullavington. 2.3.3 Filton 'Dazzle Defence': July to December 1940 An interesting experiment also started in mid-July when a detachment of the 354th Searchlight Battery were deployed on the so called 'Dazzle Defence' of Filton, which was designed to 'blind' enemy pilots and bomb aimers so as to make accurate bombing impossible. It consisted of four groups of three searchlights, each not more than 200 feet apart, being placed around Filton, the Master Group being set up on the Brickfields gun position, which was also equipped with a gunlaying radar set for the exclusive use of the searchlights. This special layout was distinct from the tactical searchlight system, its three banks of lights being exposed together with one being held in reserve. For the rest of the year the 'Dazzle Defence' remained operational, but as it failed to provide any tangible results activities were curtailed in mid-December. 2.3.4 Radar & Observer Corps Extended West: July 1940 Although mining of the Severn Estuary had been undertaken by a German submarine as early as November 1939 it was not until the night of July 17th that the Luftwaffe were in a position to commence aerial mining operations in the same waters, and the subsequent inability of the defences to track and intercept the aircraft over the Bristol Channel almost deprived shipping of the use of Avonmouth Docks. To combat this menace the Observer Corps network was immediately extended to cover Devon and Cornwall and further CHL radar stations capable of detecting the low flying He 111's employed were ordered to supplement the lone installation at Carnanton, near Newquay. 2.3.5 Heavy Anti-Aircraft Defences Strengthened: July 1940 The anti-aircraft defences of Bristol were also strengthened during July 1940, and by the 10th the manning of eight semi-mobile 3" guns which had been installed on two new sites, at Whitchurch, and Reservoir on Bedminster Down, was completed. An additional five heavy gun positions were also built during the next couple of months, although it was to be some time before the majority of them, located at Avonmouth, Almondsbury, Hambrook, Hanham and Henbury, received any weapons. 2.3.6 Balloon Barrage Suffers Lightning Strikes The summer of 1940 also highlighted a problem which was to plague balloon barrages throughout the war, that of lightning strike during a thunder storm, and locally the most serious incident of this type took place on the night of July 26th when a total of 28 balloons were hit and brought down in flames. By this time the barrage layout around the Bristol area was complete with 32 balloons flying at Avonmouth, 24 at Filton and 40 around Bristol itself. 2.3.7 Expansion of No.10 (Fighter) Group: August 1940 On August 3rd the boundaries of No.10 Group increased dramatically, with the incorporation of the Middle Wallop Sector, so important in Bristol's defence, and as the war progressed other satellite airfields came to be used in conjunction with the airfiled, including Boscombe Down, Chilbolton, and Ibsley. There remained, however, many problems in carrying out operational night flying alongside flying training at Hullavington, and so in early August the fighters were transferred to the grass airfield at Bibury in Gloucestershire. The first confirmed nocturnal victory followed soon after, when on the night of the 29th a Spitfire of No.92 Squadron at last succeeded in engaging an He 111 over Bristol, the raider eventually crashing near Fordingbridge, in Hampshire. This, however, was to prove a unique triumph for the local Spitfires which, on account of their unsuitable undercarriage configuration, were withdrawn from night operations soon after, leaving the Hurricanes to soldier on alone, but without any form of radar assistance their chances of destroying many enemy bombers was remote. 2.3.8 Decoy Sites More passive forms of defence had also been put into place in the summer of 1940 and these included the camouflage of important buildings and the construction, by the Air Ministry, of dummy airfields for daytime use, and dummy flarepaths designed to confuse enemy bomber crews at night and lure them away from the authentic aerodromes. Not only airfields were decoyed but other 'Key Points' such as aircraft factories and port facilities also needed to be covered, so in August 1940 decoy sites incorporating lights and fires were introduced for night protection. A system of sophisticated lights would operate much as one would expect those of the real target to react, while the decoy fires would be lit only when bombs fell on or near the intended target, at the same time as the real fires were extinguished, in the hope that at least some of the attack might be diverted. In the Bristol area a decoy for Filton was established at Patchway, while others were built at Long Ashton, Severn Beach, Lawrence Weston, and Portbury. 2.3.9 Gun-Laying Radar Even though gun-laying radar sets had been available for some time their deployment on heavy anti-aircraft gun sites was delayed as attempts were made to provide the equipment with some means of providing an indication of the height of enemy aircraft. Consequently, it was to be mid-August before a set arrived for installation on the Whitchurch position, and similar apparatus, which was able to detect an aircraft at a range of 40,000 yards, was soon after provided for the Gordano and Rockingham sites. As a stop gap measure in September all three sites received single 150 cm searchlights, which gave a beam of 510 million candle power, together with Sound Locators to work in conjunction with their new radar equipment in an attempt to compensate for the lack of an elevation finding facility. Nevertheless, early October did see the first electronic devices capable of determining elevation being made available for fitting to existing radar sets but accuracy was found to vary from site to site. In spite of this drawback it at last made possible reasonably good unseen fire control, and by mid-March 1941 suitably modified equipment was in operation on the Portishead, Brickfields and Whitchurch gun sites. 2.3.10 Army Bomb Disposal Although the nuisance attacks which the Germans continued to carry out against the Bristol area during the summer of 1940 inflicted little serious damage, they did assist the local defences in perfecting their organisation under combat conditions and this was especially true of the Royal Engineers bomb disposal units. A good example was the successful defusing of 250 kg bombs at Congresbury on August 17th and at Temple Street, in Bristol, on September 3rd, by Lieutenant Edward Womersley Reynolds whose bravery in rendering safe weapons on which he had not been trained was rewarded on September 17th with the award of the OBE (Military), a medal which was automatically replaced by the newly introduced George Cross seven days later. Nevertheless, the task of bomb disposal was always hazardous and the first local fatality suffered by No.7 Bomb Disposal Company occurred on September 10th when an officer was killed at their Shirehampton Depot whilst handling a German fuse. 2.3.11 Fighters to Bristol; Late September 1940 The tragedy at the BAC works caused by the devastating raid carried out on the morning of September 25th brought about a rapid review of its defences and the very next day No.504, flying Hurricanes, arrived from Croydon to take up residence at Filton, the first to be deployed in the area since April. This move proved most providential for on the morning of the 27th the Germans attempted a pin-point attack on the Parnall Aircraft plant at Yate, the raiders being successfully intercepted over Bristol by the newly arrive aircraft. In addition, in order to improve the heavy anti-aircraft gun cover for the BAC factories on the 27th the eight 3" semi-mobile guns were transferred from the Whitchurch and Reservoir positions to Henbury and Almondsbury. NEXT