In quashing democracy and timid agricultural reform, and in restoring the traditional hierarchy of the Roman Catholic Church, the army, big landowners and an authoritarian state, the Spanish version of fascism was very much a fundamentalist movement. And like so many political and religious fundamentalisms, it had a particular ferocity toward women. Franco’s troops practiced gang rape to frighten newly captured towns into submission, and until media-savvy superiors silenced them, his officers even boasted about this to American and British correspondents. Tens of thousands of women had their heads shaved and were force-fed castor oil (a powerful laxative), then jeered as they were paraded through the streets soiling themselves. Many had their breasts branded with the Falangist symbol of yoke and arrows. In Toledo, a United Press correspondent reported, Franco’s soldiers shot more than 20 pregnant women from a maternity hospital. Much larger all-female groups were executed elsewhere. Troops marched through one town waving rifles adorned with the underwear of women they had raped and murdered. “It is necessary to spread terror,” one of Franco’s senior generals declared. “We have to create the impression of mastery, eliminating without scruples or hesitation all those who do not think as we do.”

Although Preston’s sympathies are clearly with the doomed Republic, to his credit he is equally thorough in exposing the killings committed under that government. Many supporters of the Republic had their own version of class hatred, murdering large numbers of captured army officers, other right-wingers and, most notoriously, nearly 7,000 members of the Catholic clergy and religious orders, who were seen as accomplices of the reactionary landowners. Among hundreds of other atrocities on the Republican side, Preston details the evasions of the longtime Communist Party leader Santiago Carrillo regarding his involvement in the massacre of more than 2,200 rightist prisoners in Madrid; the operations of some Soviet “advisers” who, supposedly on hand to aid the Republican Army, devoted themselves to hunting down anti-Stalinists on the Spanish left; and the harshly sadistic prisons operated by the Republic’s military intelligence service. Of the 200,000 estimated civilian wartime executions, more than 49,000 took place in Republican territory — a much smaller toll than that taken by the fascists, but still enormous.

There were crucial differences, how­ever. Most, though by no means all, Republican killings were by mob violence, not deliberate policy, in the first six months of the war, as popular outrage welled up after air raids and news of fascist atrocities. But — sometimes effectively, sometimes not, and often at great personal risk — certain Republican officials managed to restrain and sometimes even prosecute killers of civilians. Unlike the tightly controlled press in Franco’s territory, some newspapers condemned the killings. And the Republican government saved many lives by evacuating from the country more than 10,000 businessmen, priests and other right-wingers thought to be at particular risk. Nothing similar happened on the Falangist side.

Franco’s rule became less murderous in later times, but in the early years he ranks morally with Hitler and Stalin. In such a regime, I always wonder, were there any decent people who tried to stop the slaughter? Yes, it turns out. Preston gives one brief but haunting example. Father Fernando Huidobro Polanco was a 34-year-old Jesuit who enthusiastically volunteered as a chaplain for Franco’s troops. But he was dismayed to see them routinely shooting all their prisoners. He sent protests to high-level army officers and finally wrote to Franco himself that “many are dying who do not deserve such a fate and who could mend their ways.” To Franco’s adjutant, he protested in despair that “we are falling back into barbarism. . . . I do not want the new regime to be born with blood on its hands.” He was wounded but then returned to the front, ever more vocal. In 1937, he was killed in battle, supposedly by shrapnel from one of the Republic’s Soviet artillery shells. Ten years later the Jesuits began the lengthy process to have him canonized as a saint. But in the course of the investigation, it came out that he’d been shot in the back by a soldier from his own unit, “tired perhaps of the preaching of his chaplain,” Preston writes. “When it was discovered that Huidobro had been killed by the Francoists and not by the Reds, the Vatican shelved his case.”