[mordechai9000]

The first English language film that comes to mind for the Spanish civil war is For Whom the Bell Tolls. It's been a while, but I don't think it has much discourse about the causes or the background for the war - but films often treat those subjects either as assumed background information the audience already has, or as something that is not needed to identify with the characters and enjoy the narrative.

So you could use it, but it would need to be accompanied by supplemental factual materials. But I think that is true of many, if not most, non-documentary popular war films.