bringing up Spain is such a funny choice. I just recently finished reading Matt Christman's ¡No Pasaran! and one of the things he repeatedly points out is that the sectarianism from the anarchist factions against the communists, while facing down the full force of the fascists backed fully by Germany and Italy, absolutely cost them the war. There is zero reason to fight someone on your side when the guys shouting "I'm gonna fuckin kill you" are bashing down your gates to fucking kill you.