After promotion to colonel, he was appointed commander of the 22nd Artillery Regiment "Aosta", stationed in Palermo, and then of the 4th Automobile Center from 1933 to 1936.

On 1 November 1939 he assumed command of the 10th Infantry Division "Piave", stationed in Padua, being promoted to major general on 1 January 1940.

[1][2] When Italy entered the Second World War, on 10 June 1940, Roncaglia was still in command of the "Piave" Division, stationed between Padua, Vicenza and Treviso.

He was temporarily placed at the disposal of the Ministry of War in Rome until May 1943; when he was given command of the XIV Corps (consisting of four Italian and one German infantry division, altogether 55,800 men), with headquarters in Podgorica (Montenegro).

On 15 September 1943 he was captured by German forces in Podgorica after the proclamation of the armistice of Cassibile; he was then held as a prisoner of war in Oflag 64/Z in Schokken, Poland, until January 1945, when he was freed by the advancing Red Army.