After graduating as ensign from the Naval Academy of Livorno in 1915, he served on various ships during World War I, being promoted to lieutenant in 1918.

[1][2] In 1935 he was transferred to the Royal Hydrographic Institute of Genoa and in 1937 he was promoted to captain, holding in succession the command of the light cruiser Luigi Cadorna, the battleship Duilio and the light cruiser Luigi di Savoia Duca degli Abruzzi.

In November 1938 he was appointed president of the Commission for the Experimentation of War Material (Mariperman) in La Spezia, and from 12 April 1940 to 10 March 1941 he served as Chief of Staff of the Naval Command of Messina.

A few weeks later, he participated in the battle of Cape Matapan, in which the 1st Naval Division, of which the 9th Destroyer Squadron was part, was annihilated by the battleships of the Mediterranean Fleet in a nocturnal engagement.

Alfieri, under the command of Toscano, was the only Italian ship that was able to put up a reaction, firing her guns and some torpedoes at the attackers before being hit and disabled by British gunfire.