 On 8 June, "U-5" torpedoed and sank the Italian troop transport "Principe Umberto" at Linguetta.Later, "U-5" fought a French-Italian destroyer group to a stalemate on 2 August, and torpedoed the Italian Q-Ship "Pantelleria" south of Taranto on August 14.On 15 September 1916, the two Austro-Hungarian seaplanes L.132 and L.135 forced the French submarine to surface by dropping bombs.