An antifascist and feminist activist, co-founder of the European Federalist Movement, Hirschmann at 19 years old in 1932 became a member of the youth organization of the Social Democratic Party that resisted the rise of the Nazis.
After meeting and subsequently marrying Eugenio Colorni, a young Italian philosopher and socialist, Hirschmann actively participated in the illegal resistance movement against fascism. When Colorni was arrested and imprisoned on the island of Ventotene, Hirschmann followed him. There they met Ernesto Rossi and Altiero Spinelli, the authors (1941) of the Ventotene Manifesto “for a free and united Europe”, which is considered by many as the beginning of European federalism. The Manifesto was widely read by those fighting with the Italian resistance against the Nazis. It called for a break with Europe’s past in order to form a new political system through political restructuring and extensive social reforms. Hirschmann secretly transported the Manifesto to mainland Italy and contributed to its dissemination.
After leaving Ventotene, she moved to Milan. There, in 1943, she became a co-founder of the European Federalist Movement (Movimento Federalista Europeo). After Colorni’s assassination by fascists, Hirschmann fled to Switzerland and participated in organizing the first international federalist conference in Paris in 1945.
Hirschmann’s political commitment continued after World War II. In 1975, she founded the association Femmes pour l’Europe (Women for Europe) in Brussels.