After the 17 July 1936 military coup in Spain began the Spanish Civil War, the Nationalists requested support from Nazi Germany and Fascist Italy.

[7] The volunteers were stationed at Tablada Airfield near Seville and, with the support of German air transport, began the airlift of Francisco Franco's troops to Spain.

[16] The first German chargé d'affaires to Franco's government, General Wilhelm Faupel,[nb 2] arrived in November and was told not to interfere in military matters.

[19] In a speech at Würzburg on 27 June 1937, Hitler said that he supported Franco to gain control of Spanish ore.[20] Discussions about German objectives for intervention took place in January 1937.

[22] A December 1936 communiqué from German ambassador to Rome Ulrich von Hassell said that Italy’s involvement in the Spanish Civil War kept it out of the Western powers' camp:

Growing Republican air superiority became increasingly apparent, particularly the strength of the Soviet Polikarpov I-15 and I-16 aircraft,[26] but historian Hugh Thomas described their armaments as "primitive".

[28] Faupel advocated the creation of a single German unit of 15,000 to 30,000 men in November and December 1936, which he believed would be enough to turn the tide of the war toward the Nationalists.

[29] New aircraft were sent to the Condor Legion between late 1936 and early 1937, including Henschel Hs 123 dive bombers and prototypes of the Heinkel He 112 and Messerschmitt Bf 109; the latter was the most successful.

[34] The use of He 51 and Ju 52s and the Legion's anti-aircraft guns in ground roles only partly mitigated the Nationalist defeat in the March Battle of Guadalajara.

The defeat of a significant Italian force and growing Soviet superiority in tanks and aircraft led the Germans to support a plan to abandon the offensive on Madrid and concentrate a series of attacks on weaker Republican-controlled areas.

[40] The Basque ground forces were in full retreat towards Bilbao through the town of Guernica, which was bombed on 26 April in one of the war's most controversial attacks.

George Steer, a reporter for The Times who was covering the Spanish Civil War from inside the country, wrote the first full account.

The Condor Legion also took part in the Battle of Brunete, a Republican offensive designed to take the pressure off northern Spain where fighting was ongoing.

[51] Heavy aerial bombardment by 200 Nationalist, German and Italian planes occurred far behind Basque lines in August 1937 and led to the fall of Santander after the 1 September battle.

[52] After the next major campaigns (Madrid and Barcelona), the Condor Legion was moved to Soria and began a week of strikes against Republican airfields.

[55] The continued Nationalist offensive on Aragon from April to June 1937, including the Battle of Belchite, involved bombing raids and the legion's ground forces.

[58] Casualties were beginning to mount for the Legion and – combined with a resurgence in Republican air activity – the Nationalist advance stalled, perhaps because of the reluctance of German commanders to supply reinforcements in light of the emerging Czechoslovak crisis.

Operating independently of the land-based division, it acted against enemy shipping, ports, coastal communications and occasionally inland targets such as bridges.

[70] Missions started as reconnaissance, but after the move from Cadiz to Melilla in Spanish Morocco in December 1936, the focus shifted to attacks on shipping.

[73] As a result, the German pocket battleship Deutschland stood guard over Ceuta to prevent interference from Republican ships while Franco transported troops to the Spanish mainland.

[74] By mid-October, the German North Sea Group around Spain consisted of the pocket battleships Deutschland and Admiral Scheer, the light cruiser Köln, and four torpedo boats.

[nb 5] The KdF fleet, including the MV Wilhelm Gustloff and seven other ships, were given secret orders on 20 May 1939 and diverted from their regular pleasure-cruise schedule to arrive in Vigo, Spain.

I urged him to give support [to Franco] under all circumstances, firstly, in order to prevent the further spread of communism in that theater and, secondly, to test my young Luftwaffe at this opportunity in this or that technical respect.

The Stuka's first mission in Spain was in February 1938, and each aircraft played a major role early in World War II.

The Germans also tested small numbers of 88 mm Flak 18 anti-aircraft artillery guns to destroy Republican tanks, fortifications and aircraft with direct fire.

In addition to combat experience, it is thought that strategic initiatives were first tested during Luftwaffe involvement in the Spanish Civil War.

Legion commander in Spain Wolfram von Richthofen became a Field Marshal during World War II and served in high Luftwaffe positions, specialising in ground attacks.

Although he was not involved in the bombing of Guernica, it was decided by German Defence Minister Peter Struck that Mölders' name would be removed from the barracks at Visselhoevede and from association with Luftwaffe Fighter Wing 74 (Jagdgeschwader 74) based in Neuburg an der Donau.

[82] On 26 April 2017, the 80th anniversary of the Guernica bombing, the Madrid City Council announced that it had dismantled the Condor Legion mausoleum at the Cementerio de la Almudena.

[nb 9] Its activities were commemorated in a special issue of Der Adler, the Luftwaffe's propaganda magazine, which was circulated in Spain and the United States.