Spanish Civil War Aviacion Nacional or Fuerza Aerea Nacional Dorniers

The Dornier Do 17, sometimes referred to as the Fliegender Bleistift (German: "flying pencil"), was a World War II German light bomber produced by Claudius Dornier's company, Dornier Flugzeugwerke. It was designed as a Schnellbomber ("fast bomber"), a light bomber which, in theory, would be so fast that it could outrun defending fighter aircraft. The Dornier was designed with two engines mounted on a "shoulder wing" structure and possessed a twin tail fin configuration. The type was popular among its crews due to its manoeuvrable handling at low altitude, which made the Dornier capable of surprise bombing attacks. Its sleek and thin airframe made it harder to hit than other German bombers, as it presented less of a target.

Designed in the early 1930s, it was one of the three main Luftwaffe bomber types used in the first three years of the war. The Do 17 made its combat debut in 1937 during the Spanish Civil War, operating in the Legion Condor in various roles. Along with the Heinkel He 111 it was the main bomber type of the German air arm in 1939-40. The Dornier was used throughout the war, and saw action in significant numbers in every major campaign theatre as a front line aircraft until the end of 1941, when its effectiveness and usage was curtailed as its bomb load and range were limited. Production of the Dornier ended in the summer of 1940, in favour of the newer and more powerful Junkers Ju 88. The successor of the Do 17 was the much more powerful Dornier Do 217, which started to appear in strength in 1942. Even so, the Do 17 continued service in the Luftwaffe in various roles until the end of the war, as a glider tug, research and trainer aircraft. A considerable number of surviving examples were sent to other Axis nations. Few Dornier Do 17s survived the war. The last was scrapped in Finland in 1952.

The Do 17's baptism of fire came during the Spanish Civil War (1936–39), where it outpaced most enemy fighters and performed well. The Spanish nicknamed the Dornier the Bacalaos ("Codfish"). In early 1937, mass production began on the Do 17E and Do 17F series. The Do 17 F-1 was to replace the Heinkel He 70 as a high-flying fast reconnaissance aircraft, while the Do 17 E-1 was to supplant the Legion Condor's aging Heinkel He 111B bomber. However, more modern Soviet-supplied Republican aircraft were capable of intercepting the E and F variants, which prompted an upgrade of the Dornier's defensive armament.

Among the units committed to the Franco's cause was Hauptmann Rudolf Freiherr Von Moreau's 4.K/88. On 6 January 1937, it was decided by Erhard Milch, Albert Kesselring and Ernst Udet that the Legion should have more modern aircraft. Soon 12 Do 17 E-1s, as well as He 111 B-1s and Ju 86 D-1s were dispatched to serve in Spain. The unit was named VB/88 (Versuchsbomben Staffel, meaning Experimental Bomber Squadron). VB/88s Dorniers were involved in a strike around Guernica, but that particular unit's objective was a bridge, rather than civilian areas. VB/88 dropped 8 tonnes (9 tons) of bombs, while K/88 added 37 tonnes (41 tons) over the city itself causing the deaths of about 1,500 people. The bombing of VB/88 straddled the bridge. The only other target hit by the German bombers that day was the rail station. On 8 July 1937, the Dorniers flew multiple sorties to protect Nationalist forces now threatening the capital, Madrid. At this point, the Junkers Ju 86s had been withdrawn and replaced by the Do 17 Fs. In the spring of 1938, another unit, 1.A/88, equipped with Do 17s, also arrived in Spain. A total of 27 Do 17E, F and P variants were part of the Condor Legion.

The Spanish Civil War was to be the toughest test yet on the Do17 bomber. It proved to be fast, in fact was fast enough to outpace any enemy fighter, although it could not match Germany's own Bf109, but one important lesson was learnt. It was vulnerable to enemy gunfire, especially in the forward section. The nose had been shortened on the Do17E and the Do17F variants, but the firing arc of the forward gunner was restricted somewhat and the narrow diameter of the fuselage of the Do17 which was how it became known as the "Flying Pencil" meant cramped conditions for the cockpit area of the aircraft.

These lessons learnt, were applied to the Do 17U. The nose was severely cut down and the forward machine gun positioned so that it had a complete arc of fire. An enlarged forward fuselage not only gave existing crew more room, but allowed for an additional crew member if required. All these modifications were to prove successful, and they were put into the Do 17Z in 1939. It was this variant that was to see service throughout the battle of Britain and in operations during 1940 and 1941. One of the Do 17 variants, was modified as a night fighter and had a nose section of a Ju 88C fitted complete with cannon and machine guns. Additional to that was the installation of a FLIR (Forward Looking Infra Red) detector, said to be the worlds first. The first success of the use of the FLIR detector was the shooting down of a Wellington bomber of RAF Bomber Command on the night of October 16th/17th 1940 over the French-German border.

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