2.4 'Night Blitz' - November 1940 to June 1941

With unsustainable losses being suffered during daylight attacks on Britain, in mid-October the Luftwaffe made the decision to switch to much safer, but less accurate, large scale night bombing. Consequently during early November 1940 the German High Command ordered that the night raids were to be directed against Britain's manufacturing centres, to be followed by a concentrated assault on the ports as part of the policy of blockade, the attack sequence opening with a heavy raid on Coventry on the night of November 14th.

2.4.1 Countermeasures Against X-Verfahren

By this time the Germans had introduced their new radio beam bombing aid, X-Verfahren, and this was now being used by the pathfinder aircraft detailed to take part in the night attacks. The British radio countermeasures organisation had, however, responded quickly to the new threat and in early November a temporary 'Bromide' jammer had been brought into use at Birdlip, in Gloucestershire, in an attempt to render the signals from X-Verfahren unusable in the Bristol area, while more permanent equipment was later installed at Shipham, Beacon Hill, and Porlock. Nevertheless, these countermeasures proved to be relatively ineffective, and in contrast to the success obtained against the earlier Knickebein system, X-Verfahren remained largely unhindered throughout the winter of 1940/41.

2.4.2 'Starfish' Sites

The attack on Coventry highlighted the urgent need to attract enemy bombs away from targeted towns and cities, not only to protect the civil population and industry, but also to keep up morale. This lead, later in the month, to the introduction of 'Special Fires', the idea being to disguise the effect of radio counter-measures activity by starting the fires, in what might appear to an enemy to be his target area. To cover this plan the 'Special Fires' were code named 'Starfish' on December 10th. A number of sites were constructed locally, the first serving Bristol being laid out at Stockwood and Chew Magna. Additional installations were authorised soon after to provide further protection for the city, and these were set up at Downside near Brockley Combe, Kenn Moor, on Black Down near Cheddar, and Yeomouth near Kingston Seymour.

2.4.3 Searchlights Clustered: November 1940

In order to concentrate the light from the somewhat inadequate 90 cm projectors in November it was also decided that searchlights would in the future be deployed in clusters of three at intervals of 10,400 yards to be controlled from the new Searchlight Operations Room at Colerne and, in order the achieve this, over the next few months the whole local searchlight layout in Southern England was altered.

2.4.4 Night Fighters to the Bristol Area: November 1940

In an attempt to improve the local defences on November 28th a Flight of Hurricanes from No.87 Squadron transferred from Exeter, to Charmy Down, the newly completed satellite fighter aerodrome which had been built on a hill top just north of Bath, and where the concrete runways were to prove their worth in the coming winter. The other half of the squadron finally moved down from Bibury in mid-December, and for the first time in six months the unit, which was now to be used solely for night fighting, had the opportunity of operating together.

2.4.5 Heavy Anti-Aircraft Guns Increased: December 1941

As a result of the raids of November 24th and December 2nd, the first two serious night attacks on Bristol, it was felt that certain modifications should be made to the heavy anti-aircraft gun layout and so, in order to allow more guns to fire linear barrages over the south of the city, in mid-December four 3.7" mobiles were sent to the then empty Whitchurch gun site.

2.4.6 'Hampden' Patrols

At this time a new experiment in night defence was proposed in which Handley Page Hampden bombers based in Lincolnshire were to fly defensive patrols for the close protection of a number of industrial centres, including Bristol. The operation of these 'Hampden' Patrols required the improvised night fighters to fly for four hours within a radius of ten miles of the centre of the target city, with each aircraft flying at a selected altitude between 12,000 and 20,000 feet. During this time it was also arranged that no anti-aircraft guns were to engage, or searchlights expose in the patrol area. In fact, only one 'Hampden Patrol' was in fact ever flown over Bristol, this totally unsuccessful operation taking place on the night of December 6th.

2.4.7 'Operation Layers' and 'Fighter Night' Patrols

As the 'Hampden' Patrols experiment was a complete failure it was terminated eight days later, after the decision had been made to introduce concentrated patrols of 'Cats Eye' single engined fighters stepped up in layers over certain cities. The plan was that once the objective was known between twelve and twenty fighters would be ordered up to patrol above the target at a minimum of 14,000 feet, and each was to be given a specific altitude at which to fly, so as to provide a reasonable separation between aircraft. Code named 'Operation Layers', only three such missions were in fact flown in January 1941, including two over Bristol, the second being on the night of the 16th during an attack on Avonmouth when twelve Hurricanes were operating, these being drawn from No.87 Squadron at Charmy Down and the locally raised No.501 Squadron, back at Filton since mid-December.

Although the system was initially known as 'Operation Layers', in April 1941 it was renamed 'Fighter Nights'.

2.4.8 Ground Controlled Interception

A most important improvement in the defensive capability took place in early January when the first local medium range precision Ground Controlled Interception radar station came into operation at Avebury, in Wiltshire. GCI stations, which were designed to guide the pilot of a Beaufighter to the general vicinity of a raider, quickly proved successful and other sites were subsequently opened at Sopley, near Christchurch, in Hampshire, and at Durrington, near Worthing, thereby effectively covering the Luftwaffe's main approach routes to Bristol. In March 1941 the Avebury station was moved to Exminster to extend GCI coverage to the South Devon area, and the local network was further improved by the construction of additional stations at Wrafton, in North Devon, to protect the Bristol Channel, and at Long Load, near Somerton, and at Sturminster, in Dorset. From early 1941 the new GCI system enabled the Beaufighters to operate in zones off the South Coast and on the approaches to Bristol, so leaving the locally based Hurricanes free to fly 'Layers' over the threatened city.

2.4.9 Oldmixon Beaufighter 'Shadow' Factory

The Beaufighter, brought into service to replace the obsolete Blenheim, had a maximum speed of 323 mph, carried the unprecedently heavy armament of four 20 mm Hispano cannon and six 0.303" machine guns, and to compound its effectiveness was fitted with the latest Airborne Interception radar which made it possible to track targets to a minimum range of 140 yards. Although the first of these twin-engined aircraft had been delivered to the famous No.604 Squadron at Middle Wallop in early September 1940 re-equipment was slow, partly due to the raid on the BAC factory at Filton, so that by the end of the year only seven examples had been received. Nevertheless, this situation was not to last for long as the new 'Shadow' Factory dedicated to Beaufighter construction, which had been built at Oldmixon, near Weston super Mare, was just about to commence production, the first aircraft being completed on January 20th. Although during October 1940 the unfinished plant had received some interim protection in the form of anti-aircraft machine guns, and a decoy site had been established nearby at Bleadon, it was not until late February 1941 that four 3.7" mobile heavy anti-aircraft guns had been installed on two of Weston's new gun sites at Uphill and Hutton. The weapons were to be used, not only to protect the factory, but also against raiders approaching Bristol from the south west and aerial minelayers attempting to block the approaches to local ports. A balloon barrage was also installed but it was to be early May before No.955 Squadron had all 24 balloons deployed around the factory.

2.4.10 Bomb Disposal During the 'Blitz'

At the end of January No.853 Company RE reported that since the 'Blitz' began in November 1940 the unit had attended approximately 500 unexploded bomb incidents, most of these in the Bristol area, with the greatest concentration within the city boundary, where not one bomb had been blown up in situ, all being removed safely to the Bomb Cemetery in Ashton Park. This was a considerable achievement, especially as the unit had only been engaged in the exacting science of bomb disposal for three months!

During the early spring of 1941 the Royal Navy's own Bomb Disposal Section at Avonmouth was also kept busy and was twice called to deal with unexploded bombs in ships which had been removed to the special berth in Portishead Dock reserved for vessels which were in a dangerous condition. The first incident involving a ship carrying phosphates was dealt with easily, but this was followed by a bomb aboard the American tanker 'Chesapeake' which was loaded with high octane aviation fuel. A couple of days were spent pumping out the petrol after which Lieutenant Cronyn, alone and wearing a wooden helmet attached to an airline to protect him from noxious fumes, went down into the hold and succeeded in defusing and removing the offending bomb. For this act of heroism on February 28th 1942 Temporary Lieutenant Hugh Verschoyle Cronyn RNVR was eventually gazetted with the George Medal.

2.4.11 Barrage Balloons Create a Hazard

Although a good deterrent to German shallow dive bombing the Bristol area balloon barrage proved to be far more dangerous to 'friendly' aircraft than to the enemy. Unfortunately February 1941 provided the first example locally of this problem, for it was on the 21st that a Hurricane of No.501 Squadron flew into a balloon cable at Patchway, causing the aircraft to crash 500 yards from the site and killing the pilot. Although this was the first such incident involving barrages around Bristol it was, sadly, not the last and the local balloons continued to give both regular and ferry pilots cause for concern, the most serious incident occurring some two months later when, on the night of April 30th, a Wellington bomber on a training flight from Cambridgeshire became lost. It subsequently collided with two balloon cables around Bristol's St.Andrews Park, where the aircraft crashed killing three of the crew, injuring three others and a balloon operator on the ground

2.4.12 'Pirates' Return: February and March 1941

On January 18th 1941 the weather had worsened sharply, with clouds and snow prevailing, and consequently the Avonmouth raid undertaken two days before proved to be the last heavy attack on the locality for some time. Although unfavourable conditions on the continent had ensured that Bristol remained relatively free from attention by the Luftwaffe during February and early March, although a few hand picked crews did attempt lone Pirate attacks against the Parnall Aircraft factory and the Bristol Aeroplane Company's plant at Filton.

2.4.13 Fighter Command 'Intruder' Missions

Since just before Christmas 1940 the RAF had been carrying out long-range night fighter patrols, known as 'Intruder' missions over German airfields in France in an attempt to intercept enemy bombers returning from raids on Britain and to destroy any aircraft seen on the ground. At first radarless Blenheims were employed, but it was soon decided that the Hurricane, which was having little success flying 'Cats Eye' patrols, might be better suited to this work, at least against airfields relatively close to the French coast. It was not surprising, therefore, that the first squadron selected for this work was No.87 at Charmy Down, which had been specialising in night flying since the summer of 1940. They flew their first 'Intruder' sortie on the night of March 15th 1941, and with the arrival of the first Hurricane IIC fighter-bombers in July, the pilots had at their disposal a type they considered ideal for the work.

2.4.14 Heavy Anti-Aircraft Guns Increased: March and April 1941

During the first half of March the Bristol heavy anti-aircraft gun layout had been enlarged with the deployment of an extra eight 3" semi-mobile and twenty 3.7" mobile guns on the existing sites at Almondsbury, Avonmouth, Hambrook, Henbury, as well as on three new positions at Blackboy Hill, Ashton Park, and Failand. Further changes also took place after the raid on the 16th, with three 3.7" mobiles being put in place at the new Rodway site on March 26th. The following month further modifications were made to Bristol's anti-aircraft gun layout, and on April 8th three 3.7" mobiles moved to take up position at another new site at Lodge Farm, near Portishead, however, the four 3.7" mobiles earmarked for the other additional site at Pilning were not deployed until the end of the month.

2.4.15 Colerne Sector Airfield Opened: April 1941

Although September 1940 had seen the official establishment of RAF Colerne, an old maintenance airfield lying some five miles north-north-east of Bath which was being rebuilt as a fighter Sector Station to replace Filton, during the first quarter of 1941 it still remained non-operational and heavy rain and constructional problems with the runways ensured that it remained unusable until March 26th. On that day it received No.307 (Polish) Squadron operating single-engined Boulton Paul Defiant night fighters equipped with a turret containing four 0.303" machine guns, while two days later the Beaufighters of No.600 also arrived to take up residence. Finally, all work on the airfield was completed and on April 25th Colerne was at last able to take over Filton's Sector responsibilities, Charmy Down from then on acting as its satellite.

By this time a turning point had been reached regarding the RAF's night fighting capability and from then on Luftwaffe losses during nocturnal raids steadily mounted, principally as a result of introduction of the GCI system. During April and May No.604 Squadron, which under the command of the legendary Squadron Leader John Cunningham went on to become the highest scoring night fighter squadron in the RAF, succeeded in destroying 30 enemy aircraft, including three He 111's engaged in raids on Bristol. No.600 Squadron at Colerne also began to score regularly, shooting down a Ju 88 and an He 111 before the end of the April and two He 111's early in May.

2.4.16 Searchlight Control Radar Introduced: April 1941

By the spring of 1941 a new Searchlight Control radar had been introduced the equipment being fitted to the light projector itself. With a maximum detection range of about eight miles on a twin-engined aircraft, SLC was used before the light was switched on to accurately align the projector on its target. At the end of April some ten sets were deployed locally, with further equipment becoming operational early in May.

2.4.17 Gun Defended Area Increased: May 1941

The spring of 1941 also saw the anti-aircraft gun layout around Bristol yet again under review, this time with the object of engaging enemy aircraft further out from the existing Gun Defended Area. To this end, early in May, the Failand position was moved to Backwell and that at Ashton Park to Chew Stoke, while two additional sites were also planned at Gaunt's Earthcott and Henfield. Some of the previously used positions were then abandoned and others renamed. As a result of this reorganisation for the rest of the war 20 gun sites were maintained around the city, and were henceforth known as Portbury (Portishead renamed), Lodge Farm, Gordano (re-named Markham in June 1944), St.Georges (Avonmouth renamed), Cribbs, Westbury, Rockingham, Pilning, Almondsbury, Earthcott, Brickfields, Henfield, Purdown, Rodway, Hanham, Keynsham, Whitchurch, Chew, Reservoir and Backwell.

2.4.18 Diminishing Threat: May and June 1941