In mid-1933, Messerschmitt began work on a four-passenger light transport of cantilever low-wing monoplane design, with retractable landing gear. Completed in the spring of 1934, the BFW M.37, later redesignated Bf-108 Taifun (“typhoon”), was entered in the fourth Challenge de Tourisme Internationale. Although the Bf-108 did not win any of the events, its performance was impressive, and it earned a production contract.

Even before the Bf-108 had made its first flight, Messerschmitt learned that the RLM (Reichsluftfahrtministerium, or air ministry) was about to issue a specification for a fighter, to be powered by the Junkers Jumo 210 engine and to be capable of at least 280 mph. Officially, most German airplane manufacturers were invited to submit designs; unofficially, only the established firms like Arado, Heinkel, Fieseler and Focke Wulf could expect serious consideration. Milch did not even inform BFW of the competition, but unknown to him, his superior, Aviation Minister Hermann Göring, had forwarded a confidential message to Messerschmitt, asking him to develop “a lighting-fast courier plane which needs only to be a single-seater.” It was obvious to Messerschmitt that Göring was actually alluding to a fighter.

Messerschmitt and the design team at BFW’s Augsburg factory–principally Robert Lusser, Richard Bauer and Hubert Bauer–set about incorporating the Bf-108′s features into a low-wing monoplane fighter with retractable landing gear, an enclosed cockpit, leading-edge slots and trailing-edge flaps in the wings. While work proceeded on the Versuchs (prototype) Bf-109 fighter, Germany officially established the Luftwaffe on March 1, 1935, and Adolf Hitler publicly renounced the Treaty of Versailles restrictions on German rearmament on March 16.

The prototype Bf-109V-1 was completed in August 1935, and evaluation flights began at the RLM’s test center at Rechlin, initially using a 675-hp Rolls-Royce Kestrel engine in place of the Jumo. The Bf-109V-2, completed in October, introduced the 610-hp Jumo 210A as well as a strengthened undercarriage, and the Bf-109V-3, delivered in June 1936, was the first to be armed with an engine-mounted 7.92mm MG 17 machine gun.

In spite of its high wing loading, which limited its maneuverability at low speeds, the Bf-109 yielded such outstanding performance that the RLM quickly eliminated the Arado Ar-80 and Focke Wulf Fw-159 from consideration. That left only the Heinkel He-112 as a possible competitor. Ten preproduction Bf-109B-0s were ordered, but then two events occurred that would affect the Bf-109′s fate.

June 1936 saw the issuance by Britain’s Royal Air Force of production contracts for 600 Hawker Hurricane fighters and 310 Supermarine Spitfires. The latter, first flown on March 5, had characteristics similar to the Bf-109V-1′s. The potential threat posed by those new British fighters added urgency to Germany’s fighter development efforts, and armament on the Bf-109V-4, introduced in November, was increased to three MG 17s.

The other pivotal event was the revolt of Spain’s conservative elements under General Francisco Franco y Bahamonde against the Republican government, followed by the dispatch of German aircraft to Franco’s aid, all of which occurred in July 1936. The following November, eagerLuftwaffe volunteers were formed into the Condor Legion to fight for Franco’s Nationalists. By then the Soviet Union had sent aircraft and pilots to aid the Spanish Republic, including the Polikarpov I-15 biplane and the I-16, the world’s first low-wing monoplane fighter with retractable landing gear and an enclosed canopy. To the Germans’ alarm, both Soviet fighters completely outclassed their Heinkel He-51 biplanes. In consequence, the Germans rushed the Bf-109V-4 to Spain in December, to be followed by Bf-109B-1s (aka “Berthas”), the first of which left the production line in February 1937. Spain would provide a combat environment in which to refine the Bf-109 as a fighter–and the tactics to use it to best effect.

The first operational unit in Spain, 2. Staffel of Jagdgruppe 88 (2.J/88) under OberleutnantGünther Lützow, began receiving its new fighters in March. Operations were initially plagued by accidents, but its pilots soon overcame the challenge of taking off and landing on a narrow-track undercarriage in an airplane that tended to drop its left wing, by applying plenty of compensation with the rudder. Once they had overcome the Bf-109B’s eccentricities, they commenced operations over the Brunete salient on July 10, 1937.

The Bf-109B and its principal rival, the I-16, were at first closely matched. The Bf-109B was faster in level flight and in a dive, while the I-16 had a superior climb rate and maneuverability. Republican ace and fighter squadron leader Andres Garcia Lacalle commented in his memoirs that the I-16 was superior to the Messerschmitt up to 3,000 meters (9,840 feet), but from that altitude upward, the Bf-109B’s performance achieved complete mastery over that of the I-16.

The Messerschmitt drew first blood in the air on July 8, when Leutnant Rolf Pingel andUnteroffizier Guido Höness were credited with two Tupolev SB-2 bombers, although the Republicans attributed only one of those two losses to a Bf-109, the other having fallen victim to a Fiat C.R.32. A series of air battles fought on July 12 resulted in the downing of two Aero A-101s by Höness, an SB-2 by Pingel and three I-16s by Pingel, Feldwebel Peter Boddem andFeldwebel Adolf Buhl. Höness was shot down and killed while attacking another SB-2 that same day–the first of thousands of Messerschmitt pilots to die in combat.

During the second Ebro campaign, between July and October 1938, Oberleutnant Werner Mölders of 3.J/88 developed a significant fighter tactic. By combining two Rotte, the basic two-man elements within a Staffel, into a loose but mutually supportive team, he created an infinitely flexible offensive and defensive unit that he called the Vierfingerschwarm (“four-finger formation”). That fundamental concept would become the basis for numerous variations. Mölders himself was the leading ace of the Condor Legion, with 14 victories, and on July 15, 1941, he became the first fighter pilot to pass the 100-kill mark. When he died in a transport plane crash on November 22, 1941, his score stood at 115.

While the Bf-109 was being blooded over Spain, its capabilities were also being demonstrated to the world in Switzerland. At the Fourth International Flying Meeting, held at Zürich in July and August 1937, Bf-109Bs won four first prizes. Back in Germany, the Bf-109V-13, using a boosted 1,650-hp version of the Daimler-Benz DB 601 engine and flown by Hermann Wurster, set a landplane speed record of 379.8 mph on November 11. Ernst Heinkel, whose He-112 was rapidly losing ground to the Messerschmitt, responded with a sleeker design, the He-100. With German fighter-inspector Ernst Udet at the controls, an He-100V-3 achieved a speed of 394.4 mph on June 6, 1938, and an He-100V-8, flown by Hans Dieterle, reached 463.92 mph on March 30, 1939.

Not to be outdone, Messerschmitt undertook a major redesign of his basic fighter, producing the Me-209V-1, with a special DB 601ARJ engine that could boost its power from 1,500 hp to 2,300 hp for about one minute, bringing the maximum speed up to 469.22 mph on April 29. At that point the Bf-109 was in full production, and the Nazi Propaganda Ministry falsely designated the record-making plane the “Bf-109R” (to make it seem like a less-radical variant on an existing fighter type), while the RLM barred Heinkel from trying to outdo the Messerschmitt. As a result, that official piston-engine speed record would stand for the next 30 years.

Guided by lessons learned in Spain, Messerschmitt produced a rapid succession of improved fighters. The Bf-109C-1 (“Clara”), with a fuel-injected Jumo 210Ga engine and four machine guns, arrived in Spain in the spring of 1938, followed by the Bf-109C-2, with a fifth machine gun mounted in the engine. The Bf-109D (“Dora”), five of which joined 3./J88 in August, combined the Bf-109C-1′s four-gun armament with the Bf-109B-1′s carburetor-equipped Jumo 210Da engine. Meanwhile, Messerschmitt’s experiments with the fuel-injected Daimler-Benz DB 600 and DB 601 engines, which were hampered by cooling problems, ultimately resulted in burying two radiators in the plane’s wings, leaving only an oil cooler under the fuselage. In addition, the DB 601A-powered Bf-109V-14′s armament increased to two MG 17 machine guns in the nose and two 20mm MG FF cannons in the wings, along with a three-bladed controllable-pitch VDM airscrew. The result was put into production in early 1939 as the Me-109E-1, soon to be nicknamed “Emil” by its pilots.

The fighter’s revised designation, which has caused confusion and controversy among aviation historians for decades, reflected the complete acquisition of BFW stock by Willy Messerschmitt in late 1938. According to the Luftwaffe‘s own historical records, the old “Bf” reference was retained for the Bf-108, the Bf-109B through D, and the Bf-110A and B Zerstörer twin-engine fighters. All other Messerschmitt products, starting with the Me-109E and Me-110C, officially used the “Me” prefix, although the issue would continue to be confused in the years to come by the appearance of the “Bf” prefix on stamped plates on various Me-109 components as late as 1945.

The Luftwaffe had 946 operational Me-109s when Germany invaded Poland on September 1, 1939. In addition, some 300 Me-109Es were exported to Switzerland, Yugoslavia, Romania and Spain between April 1939 and April 1940. Three Me-109E-3s were also shipped to Japan for evaluation early in 1941. The Japanese soon abandoned the idea of producing Emils under license, but the Allies took the possibility seriously enough to give the “Japanese Me-109″ the code name “Mike.”

Two of the export orders were to cause some embarrassment later. In May 1940, three Heinkel He-111s that had strayed into Swiss airspace were shot down by Swiss-flown Me-109Es.Reichsmarschall Hermann Göring reacted by deliberately sending France-bound bomber formations over Switzerland with an escort of Me-110s. The clashes that ensued resulted in the loss of seven more German and three Swiss aircraft, after which Göring prudently relented. When the Germans invaded Yugoslavia in April 1941, the Luftwaffe again had to deal with opposition from its own Me-109Es, fiercely flown by Yugoslav pilots.

The Emil spearheaded German air offensives against Denmark, Norway, Belgium, the Netherlands and France in 1940, overwhelming such opponents as the Fokker D.XXI, Morane-Saulnier MS.406 and Hawker Hurricane. The German Experten (aces with 10 or more victories) finally met their match over Dunkirk in May 1940, when they first encountered the Spitfire. The rivalry between those two classic fighters would continue throughout the Battle of Britain. The Messerschmitt had the advantage in high-altitude performance, as well as in the ability of its fuel-injected engine to function even while inverted, when a Spitfire’s Rolls-Royce Merlin power plant would be starved for fuel. The Spitfire’s lower wing loading endowed it with superior maneuverability, but the Messerschmitt’s principal disadvantage lay in its limited range. After 20 to 30 minutes over the average British target, a Messerschmitt pilot would have to break off his engagement or he would run out of fuel before he could return to base across the English Channel.