Yah, history can be written from various POVs. & in the Spanish Civil War, there was no lack of factions. Still, the author has a rep - he's spent his career studying, writing, teaching, lecturing about Spain, especially the Spanish CW. He has a slew of publications, speaks Spanish & Catalan fluently, resides in UK academia, has various literary honors from the Spanish-speaking world (& English-, especially about Spain). He's written a definitive (albeit dull, per Kirkus) biography of Franco.
So I'm prepared to read him, to see what he has to say on the topic.