The Spanish Civil War has been a lingering interest of mine for long time. I first began to look into it in college during a writing class focused on the Great Depression (led by the great Ronald Dorr).
My paper was on American volunteers in Spain. I enjoyed working on the project and it became a topic I returned to from time to time, but never with any close attention.
I tend to approach my hobbies and topics in a manic way - when I really get into something, I do a full immersion for weeks and then it passes and I move onto something else. (I'm at my most irritable when I have no mania.)
For whatever reason the Spanish Civil War bug never got to that point until a couple of years ago, and then it came on pretty strong. Online resources are generally useless, since they mostly regurgitate the false narrative that the war was between an embattled democracy and the nascent forces of fascism.
Indeed, the Spanish Civil War is the one instance I can think of where the losers wrote the histories. The fall of the Spanish Republic is an exercise of "lost cause-ism" that would make Confederate sympathizers blush.
Seeking the truth and deeper context, I bought Hugh Thomas' massive account of not just the war but Spanish society as whole. It was certainly thorough, but almost too much to handle. The writing is dense and contains a bewildering amount of minutae about the finer points of Spanish political culture and minor figures which really bog down the narrative.
Basically, it's the old problem of trying to drink from a fire hose. I also think by focusing on so many tiny details, Thomas obscured the bigger picture.
That's where Stanley G. Payne comes in with his book, which is also titled The Spanish Civil War.
This is the book I had wanted all along. Payne's narrative is crisp, clean and focuses with great clarity on the key points of the conflict. Payne lays it all out in a quick-moving format, outlining the causes of the war, its overall course, and its consequences. He also pauses along the way to address other topics such as the role of women in the war, foreign aid and so on.
In the process he destroys a number of pernicious myths that continue to be repeated. No, the Spanish Republic was not a "struggling democracy," but merely a vehicle for revolution, something its leaders openly admitted at the time.
The Republican" Popular Army" was set up on Soviet lines complete with political officers (commissars) empowered to execute subversives. They even wore a red star in the center of their cap! Had the Republic prevailed, it would have done so as a Soviet-sponsored communist dictatorship. Not exactly a win for democracy.
Payne also uses his knowledge of other 20th Century civil wars to demonstrate how Spain was unique and not just another facet of a larger clash between communism and fascism.
In fact, he provides a great deal of clarity on this topic, irrefutably demonstrating that the relationship between the Nationalists and Nazi Germany and Fascist Italy was purely transactional.
The Nazis and Fascists were creatures of the left and Italy in particular considered itself to be relentlessly progressive - the state of the future. Both dictatorships openly clashed with the Catholic Church.
The Nationalists - led by the much-maligned Francisco Franco - were arch-conservative in their outlook, interested primarily in preserving the faith, culture and heritage of Spain. Franco's reforms were moderate and incremental, which is to say completely different from what his erstwhile allies wanted to see.
This is not to say the Nationalist didn't commit atrocities, but it puts them in context with competing Republican crimes. No one's hands were clean.
I've also been reading some of the Osprey books on the topic. One of the most useful has been the The Spanish Civil War 1936-39 (1) Nationalist Forces.
It may sound strange, but over the years of looking at the topic, I could find zero information on how the Nationalist army was actually organized. This may seem obscure, but it's essential to understanding the military aspect of the war.
Here again, the bias of historians is clear, with limitless articles on the Popular Army's "mixed brigades" but not a word on the old regimental system and how it factored in the composition of battalions, regiments, brigades and divisions, not to mention uniquely Spanish terms like tercio and bandera.
I don't expect other people to share the degree of my migrating obsessions, but hopefully some of these books will get you the information you need should the topic interest you.