The engagement took place on 30 September 1916, near Sulina, when the German submarine UB-42 launched a torpedo at Smeul as the latter was escorting two minesweeping motorboats.

[7][8] This was probably caused by an encounter with Smeul, whose captain surprised a German submarine near Sulina in November 1916, the latter reportedly never returning to her base at Varna.

This could only be UC-15, whose systems most likely malfunctioned after being forced to submerge in the shallow waters, upon encountering the Romanian torpedo boat.

[9] On 16 April 1917, Smeul capsized in rough seas off the mouth of the Danube with the loss of 18 of her crew, including 3 French naval officers present on board.

[10][11] This incident has been incorrectly attributed to Ottoman mines in several English language sources, possibly as a result of wartime propaganda by the Central Powers.