In 1864, Del Santo was made an Officer of the Order of Saints Maurice and Lazarus for his role in rescuing the steamerRe Galantuomo, which had been damaged by storms. He chartered the steamer Northern Star, to join the international search for the ship, which was feared lost in the Atlantic Ocean with 400 people on board, and spent 11 days looking for it. It eventually was found and returned safely to Naples.[1][2][3][5]
In 1866, as AdmiralCarlo Pellion di Persano's deputy chief of staff, he took part in the Battle of Lissa aboard the ironcladRe d'Italia. After the ship was rammed and began to sink he continued to fight and threw himself into the water only a few moments before she went down. Clinging to a makeshift raft of debris, he was spotted just before nightfall and picked up by a launch from the steam frigatePrincipe Umberto. He later was called to testify at the Senate trial of Admiral Persano.[1][2][4][6]
On his return Del Santo assumed new duties. He had already served as commander of the second division of the naval school and was now appointed commander-in-chief of the maritime department of Naples. In 1878 he became aide-de-camp to KingUmberto I. Later general secretary at the Ministry of the Navy, he became the first commander of the new Naval Academy of Livorno in November 1881.[9] He was promoted to rear admiral in 1877 and then to vice admiral on 17 November 1883 at the same time as he was made Minister of the Navy.[2]
Del Santo hesitated to take his place, and did nothing to attract controversy during the brief months in which he served in the Council of Ministers.[4][12] In order to serve he ran for office in a by-election in Genoa on 16 December 1883 and was sworn in on 28 January 1884.[13][14][15] His uneventful tenure as minister ended in March 1884 when the government resigned; when Depretis immediately formed his sixth government, he gave Benedetto Brin the navy portfolio.[16] Del Santo remained in the Chamber of Deputies until 1886.[17] He was nominated as a Senator of the Kingdom of Italy in 1890 but never took his oath of office or served as such.[2][3][18]