He remained in the background until the downfall of Mussolini on July 25, 1943 which he helped engineer. Badoglio then became Prime Minister of Italy and quickly arranged for an armistice with the Allies on September 3rd. On September 8th, Italy surrendered unconditionally. Badoglio dissolved the Fascist Party and declared war on Germany on October 13, 1943.
Cavallero became Chief of General Staff on 6 December 1940, after the resigning of Field Marshal Badoglio due to his disappointing command of the war. He also became Commander of Italian Forces fighting against Greece on 30 December 1940. Thanks to his organizational ability, he rationalized the situation and stopped the Greek counter-offensive in January 1941.