Naval warfare in southern waters was continued against British warships by the Austrian navy. On June 9, 1915, the Austrian admiralty announced that a cruiser of the type of the _Liverpool_ had been struck by a torpedo fired by an Austrian submarine while the former was off San Giovanni di Medua, near the Albanian coast. Reports of the incident issued by the Austrian and British naval authorities differed, the former claiming that the cruiser had sunk, and the latter that it had remained afloat and had been towed to an Adriatic port. Most unique was an engagement between the Italian submarine _Medusa_ and a similar craft flying the Austrian flag on June 17, 1915. This was the first time that two submarines had ever fought with each other. On that day the two submarines, the presence of each unknown to the other, lay submerged, not a great distance apart. The _Medusa_, after some hours, came up, allowing only her periscope to show; seeing no enemy about, her commander brought the rest of her out of the water. She had not emerged many moments before the Austrian vessel also came up for a look around and the commander of the latter espied the Italian submarine through his periscope. He immediately ordered a torpedo fired; it found a mark in the hull of the _Medusa_ and she was sent to the bottom. One of her officers and four of her men were rescued by the Austrian submarine and made prisoners. Italy's navy was not to continue to act as a separate naval unit in the southern naval theatre of war, for on June 18, 1915, the Minister of Marine of France announced that the "Anglo-French forces in the Mediterranean were cooperating with the Italian fleet, whose participation made possible a more effective patrol of the Adriatic. Warships of the Allies were engaged in finding and destroying oil depots from which the enemy's submarines had been replenishing their supplies." This effective patrol did not, however, prevent an Austrian submarine from sinking an Italian torpedo boat on June 27, 1915.