at the start of the first world war krepost sveaborg was subordinated to the russian 6th army. in summer 1916 krepost sveaborg was subordinated to baltic fleet. at the start of the war krepost sveaborg was divided into three defensive areas, with the sea front forming one defensive area and the land front divided to pasila and laajasalo-herttoniemi areas. the sea front was further divided into six sectors, with sectors 1-4 at the old fortress, sector 5 at melkki and sector 6 at isosaari. the sea front was divided into main line of defence from melkki to isosaari and second line of defence from lauttasaari to santahamina at the end of 1914. as the new batteries were constructed melkki was relegated to second line of defence and lauttasaari to land front in spring 1915. at the land front new defensive lines were constructed from 1915 onward further away from the city center. the new land front was divided into three sectors: eastern, northern and western.<ref name="viapori/vyohyke"></ref> krepost sveaborg was also responsible for a larger fortification district that included coast line west of the fortress until hanko.