I don’t know how the war would have gone if those events hadn’t taken place, but it seems to have undermined the strength of the popular front. And from what I’ve read the anarchists were sufficiently organized. The type of Anarchism popular amongst the Spanish was a syndicalist strain very different from the hyper-individualism people expect from anarchists today.
Why do you think it happened? You implied the fighting was one-sided and a betrayal.
Why what happened? As far as why Anarchists were attacked by communists, it is ppssible the USSR was more interested in developing a strategic ally than simply fighting Fascists. As far as why Franco won, I think the biggest reason was his much greater international support from Germany, Italy, and even American corporate powers.
You’re dancing around the issues, I’m asking why you say the Communists “betrayed” the Anarchists, as though it was a one-sided afair.