The groundbreaking new de Havilland B Mk IV Mosquito was ultimately delivered to the Blenheim-equipped No 105 Sqn of No 2 Group at Swanton Morley airfield in Norfolk in November 1941, making them the RAF Bomber Command’s first unit to use it. The bomber/photo-reconnaissance (PR) prototype (W4050), which had taken to the air on November 25, 1940, was the only one in use by 1941. A lengthy and occasionally unpleasant development phase preceded the start of production, and at one point the project was almost completely abandoned. Before it had left the drawing board, de Havilland executives at Hatfield believed that their two-crew, unarmed, wooden bomber design, which relied solely on speed to outrun opposing fighters, was a winner.
Nonetheless, unarmed bombers were a sin in London at this time. On December 30, 1940, de Havilland finally obtained a contract for 150 Mosquitoes, but it was unclear how many would be fighters, how many photo-reconnaissance models, or even how many would-be bombers. The fighter variant received approval in June 1941. The Air Ministry was only convinced to order a wooden, unarmed bomber version the next month after de Havilland made a concerted effort, particularly when the Mosquito was observed to perform as the company had promised.
The prototype, which had Merlin 21 engines with two-speed, single-stage superchargers, had attained 255 mph during testing in December 1940. W4050 tested at 6000 feet on January 16th, 1941, then at 28,500 feet in July (this time powered by Merlin 61s), the aircraft reached 433 mph! After ultimately approving the bomber type, the Air Ministry placed an order for 50 aircraft, each of which could carry four 250-lb bombs. Also, it was stated that the final 10 of the 19 PR Mosquitoes that were contracted should be finished as unarmed bombers.
The B IV Series I was the name given to this aircraft, which kept the early variants’ short nacelles. The B IV bomber prototype, W4072, made its first flight on September 8th, 1941. The 27 B IV Series II bombers that were later converted into PR Mk IVs had longer nacelles, which set them apart from the 292 B IV Series II bombers that followed. These bombers could also carry two 50-gallon droppable wing tanks in addition to a 2000-lb bomb load by simply shortening the tail stabilizer of each bomb. De Havilland Chief Test Pilot Geoffrey de Havilland Jr. flew over the airfield in W4064 on November 15, 1941, leaving No 105 Sqn’s OC, Wg Cdr P H A Simmons DFC, and his crews in awe.
In terms of performance and power, the “wooden wonder” was a far cry from the Blenheim, and Geoffrey de Havilland gave the group a magnificent display of flying by racing low across the grass airport at a low altitude of 500 feet while traveling at a speed of about 300 mph. The Mosquito was then placed into a vertical bank by the Hatfield test pilot at a height of around 3000 feet before being brought into a tight circle that left vapor trails from the wing tips. The only crew members who weren’t impressed were the air gunners, who were no longer needed on the Mosquito while the navigators would need to learn how to use the radio.
On 17 November W4066- the first Mosquito bomber to enter RAF service was received at Swanton Morley by the AOC No 2 Group, AVM d’Albiac, and his staff. Horsham St. Faith, a suburb of Norwich, became the new home of No. 105 Sqn in December. Due to the necessity to create the 500-pound bomb with a shortened vane, which would let the Mosquito to carry four of them instead of only one 250-pound bomb, deliveries of the new aircraft were delayed.
Only eight Mk.IVs were in service by the middle of May 1942, and one of them (DK286) was equipped with the new Mk XIV bomb sight for operational testing. Another had the Lorenz beam approach equipment.
The de Havilland bomber made its combat debut at daybreak on May 31, 1942, in the wake of the RAF’s first-ever “Thousand Bomber” mission, which had attacked Cologne. No 2 Group was eager to dispatch Mosquitoes on operations as soon as possible. Four Mk IVs took off from Sc Faith equipped with 500-lb bombs and F.24 cameras and dropped their ordnance on the recently destroyed city; the first Mk IV was piloted by Sqn Ldr AR Oakeshott DFC.
The outcomes of Operation Millennium were then swiftly captured on camera before they headed back to base. Oakeshott was the first to arrive at the target location, flying above Cologne at a height of 24,000 feet and dropping his four bombs. The squadron leader’s photo run was impeded by smoke that had by this point settled at 14,000 ft from the “Thousand Bomber” raid. While two other Mosquitoes (flown by Pit Offs W. D. Kennard and E. R. Johnson) were shot down by anti-aircraft fire above the target area, Oakeshott dutifully made it back to Norfolk.
The following day, just after noon, two crews—Plt Off Costello Bowen and Wt Off Tommy Broom, as well as Flt Lt J E Houlston and Flt Sgt J L Armitage—again bombed Cologne from a great height, but this time they both made it back without injury. Later that afternoon, Sqn Ldr R J Channer DFC took off and flew through a dense cloud to a distance of just 60 miles from the city before descending quickly to a low level at approximately 380 mph to capture more pictures. Two more Mosquito B Mk IVs left for Cologne that evening, but just one made it back.
The second “Thousand Bomber” raid, which was conducted against Essen on June 1/2, and the third and final raid, which was launched against Bremen on June 25–26, both employed the same tactics by the Mosquitoes at Horsham Sc Faith. Flg Off and Flt Lt D A “George” Parry Victor Robson made a solo, two-hour, five-minute flight to Essen and dropped their four 500-16 bombs on the target, but once more, smoke prevented photos.
No 105 Sqn B Mk IVs conducted bombing and photo-recce sorties on June 25–26, both during and following the third “Thousand Bomber” operation. For the upcoming operations, experience from these initial sorties was beneficial. No. 139 Sqn was established at Horsham Sr Faith on June 8th, in between these historic Bomber Command operations. The unit, commanded by Wg Cdr Peter Shand DFC, was made up of crews and a few Mosquito Mk IVs from No 105 Sqn. The U-boat yards at Flensburg were attacked by four aircraft from No. 105 Squadron at a low altitude on July 2 while two Mosquitoes from No. 139 Squadron bombed the same target from a higher altitude.
The U-boat yards at Flensburg were the target of the two units’ first combined attack on July 2, when four aircraft from No. 105 Sqn attacked from a low altitude while two Mosquitoes from No. 139 Sqn bombed the same target from a high altitude.
Two Mosquitoes were destroyed by German fighters, with Gp Capt J C MacDonald being made a PoW and the recently-promoted Wg Cdr AR Oakeshott DFC being killed, along with his navigator Fig OffV F E Treherne DFM. While Flt Lt GP Hughes was being pursued by two more Fw 190s after being hit by flak, Sqn Ldr Jack Houlsron was coming off the yards being followed by three Fw 190s. By hugging the wave tops and using +12 lbs of boost, both pilots successfully made their getaway and outran their pursuer.
As a distraction for 44 Lancasters deployed to bomb the U-boat yards at Danzig, six Mosquitoes from No 105 Sqn bombed the Flensburg yards once more on July 11. Flt Lt G P Hughes and Fig Off T A Gabe were killed when their Mosquito crashed, presumably as a result of flying too low. Plt Off Laston returned with part of his fin torn away by flak. Sgt. Peter W. R. Rowland, on the other hand, had a bit better luck because DK296’s nose was still filled with chimney pot fragments when he returned to Horsham!
The remainder of July witnessed a variety of daylight operations against targets at Ijmuiden, in Holland, and cities throughout Germany, including low- and high-level bombing as well as bombing employing cloud cover. The main goal of these operations was to activate the air raid sirens, which caused the greatest amount of interruption to German industry.
The book “Mosquito bomber/fighter-bomber units 1942-45” by Martin Bowman is available to purchase here.
