With the collaboration of official diplomats, he posed as the Spanish consul-general to Hungary in the winter of 1944, and saved 5,218 Jews from deportation to Nazi extermination camps in eastern Europe.

Perlasca grew disillusioned with fascism, in particular, due to Benito Mussolini's alliance with Nazism and adoption of Italian racial laws that came into force in 1938.

[1] Perlasca worked with the Spanish Chargé d'Affaires, Ángel Sanz Briz, and other diplomats of neutral states to smuggle Jews out of Hungary.

He helped Jews find refuge in protected houses under the control of various embassies, which had extraterritorial conventions that gave them an equivalent to sovereignty.

Perlasca immediately made the false announcement that Sanz Briz was due to return from a short leave, and that he had been appointed as chargé d'affaires for the meantime.

He continued issuing safe conduct passes as initiated by Spanish government, on the basis of a Spanish decree passed 20 December 1924 that granted citizenship to Jews of Sephardic origin (descendants of Iberian Jews expelled from Spain in the late 15th century), but it had been canceled in 1930, a fact the Hungarian authorities were not aware of.

[7][8][3][4] While Perlasca was posing as the Spanish consul-general, he learned of the intentions of the SS and the far-right Hungarian Arrow Cross to destroy the ghetto.

[9][10] Back home, Perlasca drew up a detailed memorandum of the events, dated 13 October 1945, and sent it to the Spanish foreign minister in Madrid and to the Italian government, keeping a copy for himself.

[9][11] He also wrote to Sanz Briz, the ambassador who he had replaced in Budapest, who laconically replied, warning Perlasca not to expect recognition for his work.

[3] The following year Perlasca received acclaim in the United States and was welcomed by dozens of journalists and some survivors (Eva Lang, Avrham Ronai) in Washington, when the Holocaust Museum awarded him as Righteous Among the Nations.