Trident operated in most of the naval theatres of the Second World War, in home waters in the North Sea and off the Scandinavian coast, in the Mediterranean and in the Pacific far east.

In May 1940, Trident in Kors fjord Norway, destroyed a German supply ship with a torpedo, having forced it aground in an initial gun action.

Trident fired seven torpedoes against them, one of which hit Prinz Eugen in the stern and jammed her rudder and damaged her engines, but the Admiral Scheer escaped unscathed.

[2] The Reindeer was named Pollyanna after the base and apparently adapted so well to life on board (being fed table scraps and condensed milk) to the point that she ate a few navigations maps.

[2] When the submarine returned to the UK Pollyanna had grown to the extent that the services of the local slaughterman had to be used to truss her securely so she could be safely removed from the boat.