In 1940 he was commander-in-chief of the lackluster Italian invasion of Greece. Visconti Prasca's personal propaganda in convincing Benito Mussolini that the initial forces under his command would prove sufficient, and that the Italian invasion would meet a feeble resistance, was one of the factors leading to the disaster. Visconti Prasca was replaced on 13 November, only two weeks after the beginning of the invasion, by Ubaldo Soddu.