The Condor Legion was sent to Spain by Adolf Hitler to support General Franco's Nationalist movement. The Condor Legion is most famed for its attack on Guernica and few doubt that Hitler's primary purpose in sending the Condor Legion to Spain was to assess how well his new aircraft performed in battle and whether they had got their tactics correct.
The USSR had sent tanks and much ammunition to the Republicans in October 1936. This concerned Hitler and he decided to send a modern German force to support Franco against such odds.
The Condor Legion was commanded by General Hugo Sperrle. He had at his disposal 48 Heinkel HE 51's and 48 Junkers Ju 58 bombers. The force also had some Me 109's to support it when in battle. One member of the Condor Legion wrote back to his relatives that what the Condor Legion did in Spain “was better than manoeuvres”. Those who flew on missions were required to send written data to Sperrle about what went well on the mission and what did not. By doing this, Sperrle hoped to end up with almost perfect tactics for any aerial assault used by the Luftwaffe in what might prove to be future conflicts.
The leadership of the Condor Legion was rotated so that more than just one senior Luftwaffe officer all got experience of modern urban aerial warfare. After Sperrle, the unit was commanded by Helmuth Volkmann who in turn was succeeded by Freiherr von Richthofen