Meeting Mario Fiorentini was a plunge deep into the last century: a man born in the final days of World War I, who fought his most important battles after the Wehrmacht invaded his native Rome on September 8, 1943. He had early in life shown the spirit of rebellion; his father was a nonreligious Jew, and when, in 1938, Benito Mussolini’s regime proclaimed the antisemitic Racial Laws banning “mixed-race” marriages and the employment of Jews in public functions, the young Mario went to a rabbi saying he wanted to convert to Judaism; the cleric warned him against it.

During the German occupation, which also brought the deportation of his parents in the October 16, 1943 Nazi raid against the Jews of Rome, Fiorentini became a leader of the partisan Resistance. He headed the “Antonio Gramsci” unit of the Communist-led Gruppi d’Azione Patriottica (GAP), which carried out many of the most important partisan actions in the city. Faced with Nazi reprisals — and mounting no less than four prison escapes during the twenty months of struggle — he fought both German occupiers and homegrown Fascists, from Rome to the country’s northern reaches.

This autodidact’s early twenties were dominated by the fight for Liberation: he would complete his studies only after the war. He would then become a prominent mathematician, teaching in secondary schools in the outskirts of his home city before becoming professor of geometry at the University of Ferrara. Yet he was also a constant witness to the horrors of Fascism and the fighting spirit of those who resisted it — even in an era when consciousness of the past began to wane.

Already before World War II, Mario frequented an artistic world in which there circulated “non-fascists,” an incipient dissent, and influences aside from Fascism’s own: most notably a theater company that included future greats of Italian cinema like Vittorio Gassman and Lea Padovani. In his early twenties, Mario made contacts with anti-fascists like Fernando Norma, a leader of the liberal-socialist Giustizia e Libertà movement, and members of the clandestine Communist Party.

After going to war in June 1940, Fascism’s disasters had soon accelerated. Faced with sustained military defeats, the Allied invasion of Sicily and then the first aerial bombing of Rome, on the night of July 24, 1943, Fascist hierarchs moved to oust Mussolini. The monarchy sought an armistice with the Anglo-Americans — only for Adolf Hitler to order an invasion of Italy in response. Fiorentini often recalled how seeing the German tanks roll into Rome on September 8, he told his partner Lucia Ottobrini, from the Alsace region of eastern France: “Nous sommes dans un cul-de-lampe” (“We are trapped in a tight spot”). The king and the prime minister, Pietro Badoglio, fled the capital without giving orders to the Italian troops. The answer: disbanded soldiers and ordinary civilians had to take up arms.