During World War I, "78 T" was used for convoy, escort, minesweeping tasks, anti-submarine operations and shore bombardment missions. She also conducted patrols and supported seaplane raids against the Italian Adriatic coast. On 24 May 1915, "78 T" and seven other 250t-class boats were involved in the shelling of various Italian shore-based targets known as the Bombardment of Ancona, with "78 T" involved in the shelling of Porto Corsini near Ravenna. In the latter action, an Italian shore battery returned fire, hitting the scout cruiser and damaging one of the other 250t-class boats. On 23 July, "78 T" and another 250t-class boat participated in a shore bombardment and landing operation led by "Novara"s sister ship against San Benedetto del Tronto, Ortona and Termoli on the central Adriatic coast of Italy. 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, so it is possible that one of these was "78 T". This force was tasked to maintain a permanent patrol of the Albanian coastline and interdict any troop transports crossing from Italy.