 The Baltic Fleet only had four pre @-@ dreadnoughts in service , as the Second Brigade of Battleships , when World War I began , although the four dreadnoughts of the Gangut class were almost finished . After they were completed and could defend the mouth of the Gulf of Finland , Slava sailed through the Irbe Strait on 31 July 1915 to assist Russian forces defending the Gulf of Riga . More specifically she was to support the Imperial Russian Army with her guns and to defend the gulf against German naval forces . 
