it was planned in 1916 to build four two-gun batteries of 52 caliber model 1907 guns at krepost sveaborg, but the work started in 1917 never progressed beyond building gun mount foundations and some ammunition and crew shelters. the batteries were to be built on the mainland, with guns in single open positions capable of firing on both land and sea targets. the batteries were located at munkkiniemi, haaga, oulunkylä and koskela. the 305 mm guns were used later to protect helsinki however, as finland built an armoured twin turret on kuivasaari between 1931 and 1935 and two guns in open positions at isosaari during the second world war in 1941-1944.