At the outbreak of World War I on 28 July 1914, "77 T" was part of the 1st Torpedo Group of the 3rd Torpedo Craft Division of the Austro-Hungarian 1st Torpedo Craft Flotilla. During the war, she was used for convoy, patrol, escort and minesweeping tasks, anti-submarine operations, and shore bombardment missions. On 24 May 1915, she and seven other 250t-class boats participated in the Bombardment of Ancona, which involved shelling various Italian shore-based targets, with "77 T" involved in the operation against Ancona itself. In late November 1915, the Austro-Hungarian fleet deployed a force from its main fleet base at Pola to Cattaro in the southern Adriatic; this force included six of the eight T-group torpedo boats. This force was tasked to maintain a permanent patrol of the Albanian coastline and interdict any troop transports crossing from Italy.