The Allies are blockading the Strait of Otranto to restrict Austro-Hungarian U-boat access to the Mediterranean. Now Admiral Horthy, the commander of the Austro-Hungarian fleet, leads a powerful force out to attack the blockade. However, as the Austro-Hungarians move to their assembly positions at night in advance of their sortie, they find themselves under attack by Italian torpedo boats. This should be a one-sided battle, as one blast from the heavy guns of the Austro-Hungarian capital ships would blow the torpedo boats out of the water, but in the darkness confusion reigns. The Italian MAS 15 manages to hit the battleship Szent István with two torpedoes before making its escape. The Szent István sinks and Horthy, fearing that his attack plan has been rumbled, orders his ships to return to port.
The sinking of the Szent István (WW2 Weapons: Diary June 10, 1918)