ROME – As World War II neared, Pope Pius XI considered ties with French communists as a way to oppose Nazism, says a historian studying recently opened Vatican secret archives.

Pius shared his thoughts with Vatican Secretary of State Cardinal Eugenio Pacelli, who succeeded him as wartime pontiff Pius XII, according to history professor Emma Fattorini, who wrote about her findings in Sunday’s Il Sole-24 Ore, Italy’s main business daily.

Although Pius had considered far-right regimes a bulwark against communism, he had a change of heart as the dangers of fascism and Nazism became apparent, Fattorini added in an interview with the Associated Press.

After “a sleepless night,” Pius XI told Pacelli he was pondering the so-called “extended hand” policy that French communist leader Maurice Thorez had used in an overture to French Catholics, the historian wrote, quoting Pacelli’s diary entry of Nov. 6, 1937.

“It’s not that he suddenly became pro-communist,” Fattorini said. “He remained a conservative, but there are signs that show he was taking a very open stance.”

Thorez previously had said in a radio broadcast that the French secular government was extending a hand to Catholic workers. Given Thorez’s strong ties with the Soviet Union, Pius initially dismissed the appeal, but “after this meditation he changed his mind, deciding to take that hand for the common good,” Fattorini told AP.

French historian Philippe Chenaux, who is studying the same section of the archives, said he had seen the document about the nocturnal reflection, but did not consider it evidence of a major turning point.

Fattorini said the pope’s reflections indicated “the inner torment that he faced in these years.”

Only a few months earlier, in March 1937, Pius had issued two encyclicals strongly condemning both Nazism and communism. But later that year “he was stressing the dangers of Nazism more, and this was a great turning point,” Fattorini noted in the interview.

As pope, Pacelli took a more diplomatic approach in leading the Vatican during the war, and was later accused by some historians and Jewish groups of failing do enough to save Jews from the Holocaust. The Vatican has insisted that Pius XII used discreet diplomacy in his efforts to help Jews.