Valencia revolting was the key to this game ending early. Loyalist forces were unable to link Catalonia with the rest of Spain AND were forced to divert forces to capture the city before being able to march on Zaragoza or adequately defend Madrid.
My mistake of not using all 3 Italian task force counters at the same time in 1936 ensured the unopposed assault on Barcelona but I think that the scanty Loyalist navy would still have been swept aside in the last turn by the Italian fleets.
As an FYI, the following regions of Spain saw no action whatsoever: Galicia, Castilla la Vieja, Leon, and Murcia. Those that saw limited action included Extremadura, Catalonia (except for one hex of Barcelona), Valencia (except for that city), Andalusia (except for the vicinity of Almeria) and Asturias (except for the quick reduction of Gijon). The bulk of the combat occurred in five provinces: Santander, Euzkadi, Navarre, Castilla la Nueva, and Aragon.