The Bristol Blenheim was originally intended as a British light bomber aircraft designed and built by the Bristol Aeroplane Company which was used extensively in the first two years and in some cases throughout the Second World War. The aircraft was originally developed as Type 142 civil airliner, in response to a challenge from Lord Rothermere to produce the fastest commercial aircraft in Europe.
It first flew in April 1935, and impressed by its performance, the Air Ministry ordered a modified design as the Type 142M for the Royal Air Force as a light medium range bomber. Deliveries of the newly named “Blenheim” to RAF squadrons commenced on 10 March 1937.
The Blenheim IV, with its redesigned and longer nose, superseded the Blenheim I on the production lines in 1938. The original short nose Blenheim I having been developed from the civil aircraft design and was one of the first new high performance monoplanes ordered under the RAF’s Expansion Plans. In all, there were some 200 Blenheim I bombers converted to Blenheim IVs and the first squadron to take delivery of these was 600 AAF Squadron based at Hendon, in September 1938. By the time war broke out, seven squadrons were operating these twin-engined aircraft.
Relatively state of the art at the time, the Blenheim was one of the first British aircraft with an all-metal stressed-skin construction, retractable landing gear, flaps, a powered gun turret and variable-pitch propellers. The Mk I was faster than most fighters in the late 1930s but the advance in development of monoplane fighters (please see our related articles e.g. Spitfire and Hurricane) made all bombers more vulnerable, particularly if flown in daylight.
One of the greatest advantages that the Blenheim had over other aircraft was its range. It could penetrate deep into enemy territory, provided that they did not come into contact with any other enemy fighters. With only a top speed on 263 mph (423 kph) and cumbersome and slow in the turn it proved extremely vulnerable to attack.
As the Allied Ground and Air Forces faced defeat in May 1940, the RAF had to use its light bomber force in desperate daylight raids against German army bridgeheads in France and the Low Countries. The Blenheim IVs (and Fairey Battles) used in these attacks suffered crippling losses. In fact no higher loss, in operations of a similar size, has ever been suffered by the Royal Air Force.
Consequently across this period, daylight Blenheim losses became a grave concern for Fighter Command and it was decided that the type would be relegated mainly to night fighter duties where 23 Squadron, who had already operated them under night time conditions, had better success. More successes came and before long the Blenheim was to prove the backbone of Fighter Command’s night fighter role.
In the German night bombing raid on London of June 18th, Blenheims accounted for five German bombers thus proving they were better suited in the nocturnal role. In July, the 600 Squadron from Manston had some of their Blenheim’s equipped with A1 Mk III radar and with this equipment a Blenheim from Ford airfield achieved the first success with this radar.
After the fighting in France was over, Coastal and Bomber Command Blenheim IVs began day and night attacks against German occupied ports and installations in frantic attempts to disrupt their invasion plans. These attacks continued throughout and into 1941 and on 4 July Wg Cdr H.I. Edwards was awarded the Victoria Cross for his part in a daylight bombing attack on Bremen while flying a Blenheim IV.
The Bristol Blenheim was used by both Bomber and Fighter Commands and it served in the European, North African and Far Eastern theatres of operation.
Today, it is still possible to see an airworthy version of the type based at the Imperial War Museum Duxford (https://www.aircraftrestorationcompany.com/blenheim) and there is also a static example at the RAF Museum, Hendon (https://www.rafmuseum.org.uk/research/collections/bristol-blenheim-iv/)