On March 16th, 1916 a huge explosion was heard and a tall water column seen just outside the Taranto harbor.
It was obvious that an enemy submarine, an Austro-Hungarian one, had hit the harbor mine defenses. On further examination, it became evident a mine layer vessel became victim of one of its weapons, it was found 31 m. deep, divided in two sections and with 10 meters entirely missing, destroyed by the explosion. Unfortunately, no one was alive inside the vessel.
Secret was imposed and the operations to salvage the submarine and recover useful information from what found inside started.
The bow section was easily recovered and some days later, after having dealt with the surviving mines and the mines from the original Italian minefield, the stern section was also brought aground.
Examination of the documents, the crew’s records, the maps and the weapons certified it was a Kriegsmarine submarine. At the time there was no war between Italy and Germany. The war would had been declared only on August 27th, 1916.
Lieutenant Eberhard Fröner and his crew were buried at the military cemetery in Taranto.
The submarine was the UC-12, a Type UC I minelayer, renamed as KuK U.24. Its war diary logged a series of mine laying operations starting on July 25, 1915 and even a trip with a weapons charge to be delivered to the Libyan rebels. It was not the only KM submarine operating in the Med under KuK flag, but this finding was the smoking gun proving the German active participation to war operations against Italy.
10.000 pages of documentation was recovered, including KuK, KM and merchant navy code books. The allied navies (British and French) were informed and given the relevant secret documents, including the submarines’ supply points map.
The submarine was then completely reconstructed and entered service as RS X1 under Regia Marina’s flag.
Complete article by A. Casanova Fuga, Bollettino d’archivio Ufficio Storico Marina Militare, Dicembre 1991 (in Italian) follows, with pictures documenting the entire operation.