During the Second World War, the Bf 109 was supplied to several states and was present in quantity on virtually every front in the western hemisphere; the fighter was still in service at the end of the conflict in 1945.

The Bf 109 was flown by the three top-scoring fighter aces of all time, who claimed 928 victories among them while flying with Jagdgeschwader 52, mainly on the Eastern Front.

[6] During 1933, the Technisches Amt (C-Amt), the technical department of the Reichsluftfahrtministerium (RLM) ("Reich Aviation Ministry"), concluded a series of research projects into the future of air combat.

The result of the studies was four broad outlines for future aircraft:[7] Rüstungsflugzeug III was intended to be a short range interceptor, replacing the Arado Ar 64 and Heinkel He 51 biplanes then in service.

[8] It has been suggested that Bayerische Flugzeugwerke (BFW) was originally not invited to participate in the competition due to personal animosity between Willy Messerschmitt and RLM director Erhard Milch;[nb 1] however, recent research by Willy Radinger and Walter Shick indicates that this may not have been the case, as all three competing companies—Arado, Heinkel and BFW—received the development contract for the L.A. 1432/33 requirements at the same time in February 1934.

V1 made its maiden flight at the end of May 1935 at the airfield located in the southernmost Augsburg neighborhood of Haunstetten, piloted by Hans-Dietrich "Bubi" Knoetzsch.

Because most fighter pilots of the Luftwaffe were used to biplanes with open cockpits, low wing loading, light g-forces and easy handling like the Heinkel He 51, they were very critical of the Bf 109 at first.

However, it soon became one of the frontrunners in the contest, as the Arado and Focke-Wulf entries, which were intended as "backup" programmes to safeguard against failure of the two favourites, proved to be completely outclassed.

[11] Initially, the Bf 109 was regarded with disfavour by E-Stelle test pilots because of its steep ground angle, which resulted in poor forward visibility when taxiing; the sideways-hinged cockpit canopy, which could not be opened in flight (but could be dropped by the emergency arm).

However, the He 112 was also structurally complicated, being 18% heavier than the Bf 109, and it soon became clear that the thick wing, which spanned 12.6 m (41 ft 4 in) with an area of 23.2 m2 (249.7 ft2) on the first prototype (V1), was a disadvantage for a light fighter, decreasing the aircraft's rate of roll and manoeuvrability.

[16] As with the earlier Bf 108, the new design was based on Messerschmitt's "lightweight construction" principle, which aimed to minimise the number of separate parts in the aircraft.

All of the main pipe connections were colour-coded and grouped in one place, where possible, and electrical equipment plugged into junction boxes mounted on the firewall.

The entire powerplant could be removed or replaced as a unit in a matter of minutes,[18] a potential step to the eventual adoption of the unitized-powerplant Kraftei engine mounting concept used by many German combat aircraft designs, later in the war years.

Another example of the Bf 109's advanced design was the use of a single, I-beam main spar in the wing, positioned more aft than usual (to give enough room for the retracted wheel), thus forming a stiff D-shaped torsion box.

The slats increased the lift of the wing considerably when deployed, greatly improving the horizontal maneuverability of the aircraft, as several Luftwaffe veterans, such as Erwin Leykauf, attest.

An alternative arrangement was also designed, consisting of a single autocannon firing through a blast tube between the cylinder banks of the engine, known as a Motorkanone mount in German.

When it was discovered in 1937 that the RAF was planning eight-gun batteries for its new Hawker Hurricane and Supermarine Spitfire fighters, it was decided that the Bf 109 should be more heavily armed.

[31] Galland had his Bf 109F-2 field-modified with a 20 mm MG FF/M autocannon, the "/M" suffix indicating the capability of firing thin-walled 20mm mine shells, installed internally in each wing.

[32] By comparison, the installed weight of a similar armament of two 20 mm MG 151/20 cannon inside the wings of the Fw 190A-4/U8 was 130 kg (287 lb), without ammunition.

In July 1937, not long after the public debut of the new fighter, three Bf 109Bs took part in the Flugmeeting airshow in Zürich under the command of Major Seidemann.

[46] When the Bf 109 was designed in 1934, by a team led by Willy Messerschmitt and Robert Lusser,[47] its primary role was that of a high-speed, short-range interceptor.

Considered by many as the high-water mark of Bf 109 development, the F series abandoned the wing cannon and concentrated all armament in the forward fuselage with a pair of synchronized machine guns above and a single 15 or 20 mm Motorkanone-mount cannon behind the engine, the latter firing between the cylinder banks and through the propeller hub, itself covered by a more streamlined, half-elliptical shaped spinner that better matched the streamlining of the reshaped cowling, abandoning the smaller, conical spinner of the Emil subtype.

Its initial variants (G-1 through G-4) differed only in minor details from the Bf 109F, most notably in the more powerful 1,475 PS (1,085 kW; 1,455 hp) DB 605 engine.

[56] The final production version of the Bf 109 was the K series or Kurfürst, introduced in late 1944, powered by the DB 605D engine with up to 2,000 PS (1,471 kW; 1,973 hp).

[63] The Flossenbürg camp system had become a key supplier of Bf 109 parts by February 1944, when Messerschmitt's Regensburg plant was bombed again during "Big Week".

[64][65][66][67] After the August 1943 Regensburg raid, some Bf 109 production was relocated to Gusen concentration camp in Austria,[68][69] where the average prisoner's life expectancy was six months.

In 1942, it began to be partially replaced in Western Europe by a new German fighter, the Focke-Wulf Fw 190, but it continued to serve in a multitude of roles on the Eastern Front and in the Defense of the Reich, as well as in the Mediterranean Theatre of Operations and with Erwin Rommel's Afrikakorps.

Later in the war, when Allied victories began to bring the fight closer, and then in German territory, bombing raids supplied plenty of targets for the Luftwaffe.

This unique combination of events — until American long-range fighters appeared very early in 1944, that steadily gave the Allies daylight air supremacy over the Reich — led to the highest-ever individual pilot victory scores.

Data from The Great Book of Fighters[89] and the Finnish Air Force Bf 109 Manual[citation needed]General characteristics Performance Armament Avionics FuG 16Z radio Related development Aircraft of comparable role, configuration, and era