rysäkari island had the westernmost 10-inch battery, and could command the western sea routes up to south-western shores of porkkalanniemi peninsula. construction of the battery located in the middle of the island began shortly after the war broke up, in october 1914. the guns, transported from vladivostok, were installed by january 1915 and the entire battery with ammunition cellars and concrete command tower was finished in spring 1916. the island had two searchlights, larger 200 cm and a smaller 150 cm one.