U5 01 Apr 1910

05 Nov 1914 unsuccessfully torpedoed by French cruiser Victor Hugo. 28 Nov 1914 captured Montenegrin sailing ship Fiore Del Mare.

26/27 Apr 1915 torpedoed and sank French armoured cruiser Léon Gambetta. 05 Aug 1915 torpedoed and sank Italian submarine Nereide, which was defending Pelagosa. 29 Aug 1915 captured Greek steamship Cefalonia off Durazzo. 14 Oct 1915 von Trapp transferred to U14.

24 Jan 16 at Gjenovic. 08 Jun 1916 torpedoed and sank Italian troop ship Principe Umberto off Linguetta.

Mined and sunk off Pola 16 May 1917 while making a mock attack on SS Kvarner; salved June 1917.

Recommissioned 27 Aug 1918 for training.

To Italy on 25 Mar 1919; b/u 1920.