coastal fortifications on the naval front protected krepost sveaborg from an attack from the sea. during the war new fortifications were built on the outlying islands pushing the defences outward to protect the ships in the harbour from new modern guns. during the first world war the naval front of the fortress was modernized almost completely. the new gun batteries can be divided into four types: heavy long range batteries, close range batteries, anti-landing batteries equipped with field guns and anti-aircraft batteries which appeared during the war for the first time. the naval front was divided into six sectors at the start of the war with sectors 1-4 comprising the old fortress, sector 5 isosaari and sector 6 melkki. the central fire control post was located in vallisaari. as the new coastal forts were completed the organization changed and the naval front was divided into two parts: an outer main line of defence from melkki to isosaari and an inner second line of defence from lauttasaari to santahamina. the naval front command post was located in vallisaari and the main artillery command post in kuivasaari.