[13] She fired on a special service vessel north-west of Ireland on the night[clarification needed] of 19 August; the torpedo missed.

On her return journey, by way of the Irish Channel,[13] U-79 compelled Nanna to take her under tow to the Danish coast,[13] likely as a result of engine damage she reported 26 January.

[13] She made three more minelaying patrols in 1917, one off the Butt of Lewis between 6 June and 4 July;[13] one in Rathlin Sound and off Inishtrahull Island,[13] between 12 September and 15 October, during which she also sank the armoured cruiser HMS Drake off Rathlin Island, 11 October, avoiding Heligoland Bight (per a 10 October general order)[14] on her return; and one between 17 and 20 December, off the Dutch coast, transiting Heligoland Bight inbound and outbound on this occasion.

[13] British Naval Intelligence (better known as Room 40) records her at Norderney on 2 May 1918, and possibly in the Elbe on 9 November.

Reduced to reserve in 1930, the boat was stricken on 27 July 1935, condemned two days later, and sold to L'Hermitte (Brest) for FF 70,642 on 6 August 1936, to be broken up.