ABSTRACT
The Allies recognized that the Otranto barrage was inefficient and up to May 1917 they could only be sure about destroying one submarine, the Austrian U6 caught in the nets in May 1916. Naturally, they thought they had accounted for more and perhaps some submarines which disappeared, like the German UB44 and the Austrian U30, may also have been claimed by the barrage, but one will never know. The Allies also liked to think that the Austrian raids on the drifters were invariably provoked or were a form of retaliation, which meant that the drifters, at the very least, were causing the enemy serious inconvenience. After the heavy losses of 15 May, Rear-Admiral Mark Kerr consoled himself with the thought that probably some of the submarines reported in the nets in the past month had been destroyed, despite unconvincing evidence. The Austrians had never raided the line except after losing a submarine and this time used a larger force and undertook a greater risk. Commodore Heneage also thought that only serious inconvenience caused by the drifters made the Austrians think it was worth risking three light cruisers against the powerful Allied forces at Brindisi. 1
