Germany saw the Spanish Civil War as a testing ground for WW2.
The Nationalists received almost double the amount of aircraft as the Republicans (1300 airplanes). Franco's airforce was almost as big as the British RAF.
While German and Italian increased supplies during the war, the Soviet Union's supplies decreased.
German commanders of the Condor Legion helped develop new tactics, such as new fighter formations.
For the Nationalists, aircraft played a large role in sinking ships. Italian and German aircraft sunk 115 Republican and 51 foreign merchant ships.
Although Mexico sent arms to the Republicans, their arms industry was very small.