at the start of the war the fortification artillery units manning the fortress were organized into nine artillery companies and a machine gun detachment. in april 1915 the fortification artillery units were reorganized into a single fortification artillery regiment with three battalions and a machine gun company. four companies manned the coastal forts at sea front. in june 1916 the regiment was divided in two, with 1st regiment responsible for the seaward defence and the 2nd for the landward defence. both regiments had ten companies in three battalions. the 1st regiment was divided into three defence detachments, with south-western and south-eastern detachments responsible for the main line of defence on the outlying islands with the newest guns, while the third detachment manned the second line on the old fortress. the artillery regiments had a common supply unit responsible for the weapons, ammunition, transportation between islands etc. a signals company built and maintained the communication lines. the minefields around the fortress were built by the krepost sveaborg mine company, from 1915 a mine battalion. in 1916 the fortress was reinforced by the mine battalion from vladivostok fortress. construction and engineering department of the fortress headquarters organized the construction works of the fortress with engineering and sapper units as well as the civilian workers.