Russia testing submarines as protection of Port Arthur according to the Dutch newspaper Nieuwe Tilburgsche Courant dated 2 May 1904

Submarine launched for defence of Vladivostok

An item reported that the trials executed by the Russian navy with her submarines at Port Arthur were successful.(1) It became clear that the submarines were able to operate an acceptable long period while submerged. Their number was now enough to protect the coast line off Port Arthur.

Note
1. At that moment was the war going on between Russia and Japan (8 February 1904-5 September 1905).