How did hitler and mussolini use the spanish civil war to their advantage?

The main reason for the help of Nazi Germany to Franco was that Hitler considered that in the "inevitable" European war that was to break out in the coming years it would be better to have in Spain a favorable government led by anti-Communist military than by a Republican that would reinforce its links with France (and with its ally Great Britain) and with the Soviet Union. In Hitler's decision they also counted two other factors, one ideological (according to Nazi propaganda, the Spanish war was a confrontation between "fascists" and "Marxists", blaming the Soviet Union and "international communism" for having caused it) and another military (experiencing new weapons and new tactics, which resulted in the deployment in the rebel zone of a complete air unit, supported by tanks and anti-aircraft guns, called the «Condor Legion»). The fighters Messerschmitt Bf 109 and Junkers Ju 87 A / B and the bombers Junkers Ju 52 and Heinkel He 111 were tested. Likewise, they launched their bombing tactics on cities in Spain. Although it was not the only one, the most famous was the bombing of Guernica represented by Picasso in his Guernica painting, exhibited in the Spanish pavilion of the Universal Exposition in Paris in 1937.

The main reason for the help of fascist Italy was to win an ally for Mussolini's project of building an empire in the Mediterranean, and thereby weaken the military position of France and Great Britain. Also, like the Nazis, it used anti-communism in his propaganda to justify intervention in the Spanish Civil War.

there were abundant sources of fuel nearby