1866 and fought with him first in Trentino then at Mentana and in France. After being elected to the Chamber of Deputies in 1880, Fortis initially worked under Francesco Crispi as Under Secretary of the Interior (1887-1890). He served as Agriculture Minister from 1898 to 1899 in the first government of Luigi Pelloux (June 1898-May 1899).

He resigned in 1899 and subsequently joined the liberal opposition of Giovanni Giolitti,