vallisaari and kuninkaansaari are located between suomenlinna and santahamina. the two islands were joined by a causeway across kukisalmi strait at the turn of the 19th and 20th centuries. from the late 19th century until the first world war vallisaari was the most heavily fortified island of the fortress. construction of a 6-inch canet battery on the island began in 1912, but the guns were relocated to the outer islands on the new main line of defence at the beginning of the war. of the older guns a five-gun battery of 11 inch model 1877 guns and six-gun battery of 11 inch mortars were still used during the war. two of the mortars were transported to the land front in early 1915, and the rest were decommissioned and abandoned on their positions in 1916. a six-gun battery of 6 inch model 1877 siege guns on fortress carriages were transported to the land front by the end of 1914. newer artillery included two 57 mm guns that were replaced with four 75 mm guns in october 1914. of the kuninkaansaari batteries one four-gun battery of 11 inch model 1877 guns was kept in service. two of the five 11 inch mortars were also in use until 1915. the rest of the guns - five 9 inch model 1867 guns, four 6 inch model 1877 siege guns, two (possibly four) 9 inch mortars and three 11 inch mortars were moved to the land front shortly after the start of the war. both vallisaari and kuninkaansaari had a 150 cm searchlight stations. small nuottasaari island north of haminasalmi strait between kuninkaansaari and santahamina was armed with four 8 inch model 1867 guns in 1887, but the island had been disarmed by 1914.