The roots of the Lancaster can be found in another Avro plane, the twin-engined Manchester, which was removed from service during the middle of 1942 due to it's Rolls-Royce Vulture engines
proving far from reliable, and was replaced by ironically the Avro Lancaster. However an Avro Manchester was used to provide the base for the prototype of the Lancaster with a couple of
changes. The first was an increase from two to four engines and a change to the 1,145-hp Rolls-Royce Merlin X, which lead to the second change, the increase of the wing span. Flying for
the first time on the 9th January 1941 and the aircraft was a big improvement. And later on in January 1941 the Lancaster was sent to the Aircraft and Armament Experimental Establishment
(A&AEE) based at Boscombe Down, where it would undergo intensive trials. No 44 Squadron at Waddington would receive the prototype during September 1941 to undergo evaluation and for crew
training. The second Lancaster prototype flew on the 13th May 1941 and was powered by Merlin XX engines and featured a twin-finned tail layout as opposed to the original three-finned
layout that had featured on early version of the Avro Manchester.
Proving an instant success, an initial contract for 1,070 Lancasters was placed with more orders following. And the increased speed of development, as a result of wartime urgency, saw the
first production version flown during October 1941 and Avro Manchesters still in production were converted to Lancaster Mk Is although from 1942 they were re-designated Lancaster Mk B.I.
The Production Lancaster Mk B.Is were fitted with 1,620-hp Merlin XXIV engines and three Frazer-Nash turrets which totalled eight 0.303-in machine-guns, four in the tail and two each for
the nose and mid upper dorsal. However due to the influx of orders other companies took on production of the new airplane to take the pressure of the company's Cheadderton and Yeadon
factorys as they couldn't keep up with the demand for the Lancaster. After receiving the prototype Lancaster No. 44 was the first squadron to be equipped with the new type. They also
used the Avro Lancaster for it's first operational mission when they laid mines in the Heligoland Bight on the 3rd March 1942.
It was not until five month later that the general public were informed of this new plane when on the 17th August twelve Lancasters from Nos. 44 and 97 Squadron attacked a u-boat diesel
factory in Augsburg. The raid itself was to confirm that sending heavy bombers on unescorted daylight raids was unfeesable as of the twelve Lancasters sent on the raid only five returned.
However Squadron Leaders Nettleton and Sherwood both received the Victoria Cross, although Squadron Leader Sherwood received his posthumously.
With the Avro Lancaster rolling of the production line in sufficient numbers they soon began to replace the Manchester, however as with a number of other planes, such as the Supermarine
Spitfire, the Lancaster relied on Merlin engines and as a result the Merlin engine was in danger of becoming in short supply. So to counteract this a Lancaster Mk B.II prototype was
proposed and this used four 1,735-hp Bristol Hercules VI or XVI radial engines and the prototype flew for the first time on the 26th November 1941.
During September 1942 three Mk B.IIs from the first production batch of these newly powered planes were sent to the A&AEE, and nine were sent to equip No. 61 Squadron based at Syerston,
Nottingham. This squadron was to perform service trials and had previous experience with the Lancaster after formally being a Lancaster Mk B.I squadron. Minor problems with the Mk B.II were
experienced during the early part of it's operational use and during it's six months with No. 61 Squadron they did not lose any of the planes assigned to them, so the aircraft would then
be sent to No. 115 Squadron at East Wretham during February 1943, who at that time were using Vickers Wellingtons.
Despite the Avro Lancaster Mk B.II equipping other squadrons it did have a couple of downfalls compared to it's Merlin counterpart. Firstly it's bomb load was 4,000lb less and it was not
able to fly as high and had a slower top speed and after 301 had been produced, production was ended. The Mk II flew its last mission on the 23rd September 1944 with No. 514 Squadron,
and although a few remained in service, even into the post-war era, they were mainly used as test-beds and the last Mk B.II was scrapped in 1950.
The next Lancaster Mk was the B.III powered by Packard built Merlin engines it also featured minor changes to the equipment and the bomb aimer's 'bubble' was enlarged and this would be
produced alongside the Merlin engined Lancaster B.I. It was also a converted Lancaster B.III that was used for the Dambusters raid, modified to carry the Barnes Wallis designed 'Bouncing
||"The Lancaster beyond doubt, was a major factor in beating the Nazi enemy down to defeat - as even the enemy admitted."
Sir Arthur T. Harris, Air Officer Commanding-in-Chief, Bomber Command
The Mk B.VI was next, the two Lancaster Mk's before this the Mk B.IV and B.V had been redesigned so much they were renamed the Avro Lincoln B.1 and B.2 respectively, and it was suggested
to use either of the Merlin 85 or 87 engines. As a result Rolls-Royce received nine airframes for comparative tests. Several of these airframes were used by No. 635 Squadron operationally
as Pathfinders with a improved H25 radar bombing aid and early electronic countermeasures equipment and both nose and dorsal turrets removed. But despite showing much improved performance
over early Lancasters none were produced and was removed from service in November 1944, with the aircraft used for a number of different tests and experiments.
The Canadian built Lancaster Mk B.X was next powered by Packard built Merlin engines it was similar to the Mk B.III with instrumentation and electronics which were Canadian and US built
and the armament for this plane was fitted once the aircraft arrived in the UK. The final production Avro Lancaster was the Mk B.VIII this had the American Marin dorsal turret with it's
two 0.50-in machine-guns replacing the Frazer-Nash turret. The Marin turret was also placed further forward compared to previous Mks.
As the tide of the Second World War changed and the role of the Royal Air Force (RAF) changed from defence to offence, the development of bombs meant that the Lancaster development
progressed alongside the bombs available at the time. This can be seen in the development of the Lancasters bomb-bay originally able to carry bomb-loads of 4,000lb then 8,000lb and
12,000lb or 'Tallboy' bombs and finally the 22,000lb 'Grand Slam' the latter two bombs were also designed by Barnes Wallis.
The Lancaster, alongside the Handley Page Halifax and Short Stirling, was the mainstay of Bomber Command's strategic bombing campaign against Germany during 1942 - 1945 and also played a
part in attacking vital targets in France in the run up to D-Day. The Avro Lancaster was also used for a number of special missions two of the most famous would be Operation Chastise and
the attack on the German battleship the Tirpitz. Operation Chastise, or as now more commonly known the Dambusters raid, involved nineteen Lancaster Mk B.III specially converted to hold a
'Bouncing Bomb' and led by Wing Commander Guy Gibson and having to drop their bombs from just 60ft they attacked the Mohne, Eder and Sorpe dams breaching the first two and causing minor
damage to the third, however this success came at a heavy price as ten aircraft failed to return.
The operation to sink the Tirpitz resulted in three attacks by a number of different aircraft, including the Fairey Barracuda, and Lancasters again using a Barnes Wallis designed bomb the
12,000lb 'Tallboy'. The first attack scored one hit on the bow of the Tirpitz making the ship unseaworthy. The second attack saw no direct hits but a near-miss did bend the ships propeller
shaft. The third attack saw three direct hits and on the 12th November 1944 the Tirpitz was sunk.
By the end of the war the Avro Lancaster had been on over 156,000 sorties and equipped at least 59 squadrons of Bomber Command. Post-war use saw a number of Lancasters converted for civil
use and re-named Lancastrion, and four Mk B.IIIs were converted for the use of testing in-flight refuelling with two serving as tankers and two as the receiving aircraft. One of these flew
non-stop from London to Bermuda, a total of 3,459 miles, and the two tankers also took part in the Berlin airlift. The Lancaster was also to provide the base for it's successor the Avro
Lincoln and a number of aspects of the Lancaster were also used on the transport aircraft the Avro York. The last Lancaster to roll off the production line was a Mk B.I, which from 1945
was re-designated B1, on the 2nd February 1946, bringing total production to 7,377.