On the 18th July 1942 Rome received news of the failure to relieve the siege of Venice. With this news having coming out to the general populace and the scale of their defeat at noon a vast crowd begins to assemble in the People's Square and many communist agitators call for a strike.
At first police are sent out into the crowds to disperse them but after a stampede occurs much of the police turn sides and a general strike occurs. With the threat of a regime collapse Mussolini attempts to leave but is caught by the crowds and beaten to death while Victor Emanuel at the same time declares he has been removed as Prime Minister and that Italy would seek an armistice with the Allies. This managed to stop a revolution occurring but much of the population were still angry and so the new Italian government had to resolve it fast.
So they declared a ceasefire and on the 8th August the treaty of Alexandria was signed.