05 March 1943,
Thousands of workers started a strike at the Fiat automotive plant in Turin, hitting the Mussolini regime in the war. The strike quickly spread to other industrial areas in Italy and within a few days there were 100,000 workers on strike. This strike is considered by many historians as the beginning of the end of Mussolini and six months later, when Germany occupied Italy in September, the partisans took the guns.
Source:
David Broder, The Strike Against Fear (Jacobin, March 5, 2018).