Paul Preston's book The Spanish Civil War: Reaction, Revolution and Revenge is good reading, as is Helen Graham's The Spanish Republic at War. Arthur H. Landis, whose book (Spain! The Unfinished Revolution) I manually transcribed by hand a few years back (and you can Google to find online as a result), is also worth looking at, e.g. how an unholy union of anarchists (namely Cipriano Mera), right-wing "Socialists" and anti-communists was formed to overthrow the NegrÃ*n Government (NegrÃ*n himself, who claimed that soon a new world war would erupt that would have an anti-fascist character and thus save the Republic, was deemed "delusional"—this being in April 1939 and the charge made by Besteiro, who claimed in the early 30's that fascism was declining in influence) and promptly capitulated to Franco.