When the Armistice of Cassibile was signed in 1943, Casali was in France where, under the pseudonym of Auguste Colombani, fought against Nazists in Collobrières.

[1] Casali returned to Italy and collaborated in the organization of the Patriotic Action Groups in Milan, with the nickname of Tino.

He played a leading role in the general insurrection that led to the liberation of Milan from the Nazi-fascist troops.

In 1969 he promoted the establishment of the "Anti-Fascist Standing Committee against Terrorism for the Defense of the Republican Order".

[2] In 2006, after the resignation of Arrigo Boldrini, Casali was elected national president of ANPI, which he directed with operational roles until 2009.