Rosi was born in Vicenza on March 19, 1881, and after enlisting in the Royal Italian Army he attended the Application School of Artillery and Engineers in Turin, graduating as second lieutenant.

Between the 1937 and 1938 he held the position of commander of the 21st Infantry Division Granatieri di Sardegna, succeeding General Carlo Geloso.

[2][1] When the Kingdom of Italy entered World War II on 10 June 1940, Rosi assumed command of the VI Army Corps that was being raised in Bologna.

On 15 February 1941 he was appointed commander of the Sixth Army, stationed in southern Italy, Sicily and Sardinia and tasked with coastal and territorial defense.

This agreement was reached at dawn on 11 September, but at eleven in the same morning German armored units under General Walter Gnamm surrounded Rosi's headquarters and captured him along with his entire staff.