I’m not justifying the coup. Once the war started both political extremes believed they had the mission to prevail whatever it took. That’s why it became a Civil War and the end of the Republican Spanish State as the way to keep law and order. That’s when the butchery began.
The Civil War atrocities came when the Republican Spanish State collapsed and a plethora of “experiments” started to pop up around the country driven by local communist, socialist and specially anarchist leaders trying to do the revolution on their own. The atrocities from the National (rebel) faction started from day one of the coup and they were driven by a centralized and unified alternative “national state” that prevailed because it was better applying law and order, even having very low support from the Spaniards.
The Anglo journalists and writers saw how some of these “experiments” worked. It’s not strange to see how they enthusiastically supported it at the beginning and how they changed their mind of even became critic with socialist mindset.