Carlo Fecia di Cossato, an Italian Duke whose family had served Royalty for generations. After a varied career in the Italian Navy, including stints in China, Abyssinia (now Ethiopia), and all over the Med, he became commander of the large but slowish submarine Regia Sommergibile (R.Smg. for Royal Submarine) Enrico Tazzoli.
In early 1942 the Tazzoli was assigned to a joint German-Italian submarine flotilla named Beta-Som for Bordeaux Sommergibile in western France on the Gironde estuary. In his only patrol to the Bahamas di Cossato sank a near-record 8 ships, sometimes twice a day, and on average one a day for a week. One of them, the Cygnet, was just 4 miles from San Salvador. Then the commander did a regrettable thing. When a gunner from the Athelqueen, a British tanker, fired back, di Cossato crash dived but emerged at the wrong time and smashed the bow of the Tazzoli into the side of the ship, badly bending it and throwing the torpedo tubes out of alignment.
As a result of the collision, di Cossato had to abort the mission and forego attacking other ships, including the British Consul, southwest of Bermuda. The sub managed to limp home to a heroes welcome, and Admiral Donitz awarded the commander highly. He was promoted to command of ships in the Med, and the sub was assigned to supply the Japanese via Singapore. On the voyage out it was detected and sunk by the Allies, and all hands were lost.
In a very fluid situation di Cossato had to turn his guns on his erstwhile Allies the Germans on the morning after Italy switched sides – he managed to sink several ships and silence a battery on shore but the situation was beginning to overwhelm him. When ordered to fight for Italians who were not aligned with the nobility (I am a bit fuzzy on all the politics), di Cossato refused and was imprisoned. When the royal court refused to grant him an audience he sadly took his own life at a young age. A poignant letter to his mother on the eve of his death is published at www.regiamarina.net.