[1] During World War I, Parona initially took part in ground fighting on the Isonzo front with the Naval Brigade; he was awarded a Silver Medal of Military Valor for an action near Monfalcone in May 1916.

[1] Later in the war, he was given command of the submarine F 17, distinguishing himself and receiving a Bronze Medal of Military Valor for an action against a convoy in the Adriatic Sea in July 1918.

[1] In 1932 Parona, together with Captain Vladimiro Pini, translated in Italian Hermann Bauer's Das Unterseeboot: Seine and Bedeutg als Teil.

In August 1940 Parona, together with German Admiral Eberhard Weichold (the Kriegsmarine liaison officer in Italy), visited a number of ports on the Atlantic coast and chose Bordeaux as the basis for the Italian submarines.

[2] Admiral Karl Dönitz and the Seekriegsleitung judged Parona favourably, for his cleverness, determination and readiness to cooperate with the German commands, while some Italian admirals considered him excessively "pro-German" and thought that he overestimated the capacity of the Italian submarines and their inexperienced crews, completely unprepared for the Atlantic conditions, to operate in the Northern Atlantic.

On 10 April 1943, 84 USAAF bombers attacked La Maddalena and the 3rd Division; Trieste was sunk and Gorizia was disabled, thus effectively annihilating Parona's command.

[1] According to one source, after the war the High Commissioner for the Epuration of the Public Administration accused him of not opposing the Germans while in Rome in the days of the armistice; of having left all the documentation of his office to Captain Carmine D'Arienzo, who was known to have adhered to the Italian Social Republic; and of having written a list of all the officers of the Italian Navy in Rome on September 8, which then ended up in German hands.

[4] After the liberation of Rome, Parona resumed active service and was appointed Commander of the Naval Department of the Ionian Sea (with headquarters in Taranto), a role that he held from 1944 to 1946.