The line is 1,200 kilometres long, stretching from the Gulf of Finland to Petsamo (now Pechenga, Russia).

[1] The planning of the Salpa Line was commissioned by general Rudolf Walden and the construction began at the end of the Winter War in 1940.

After the beginning of the Continuation War on 25 June 1941 the fortification work was stopped, pillboxes and bunkers were stripped of armaments, which were sent to the front.

The line even employed old 11 and 9 inch coastal mortars from the late 19th century, due to unavailability of more modern artillery.

The fortifications were never used in combat because the Red Army was stopped at the end of the Continuation War well before its advance units reached Salpa (see Battle of Tali-Ihantala).

In Lieksa "Viisikon Salpalinja etusema" was started to be built already during the pre-Winter War extra military training period .

[21] The Soviet forces attacked against the Viisikko positions on 9 December 1939 and it had to start to withdraw on Christmas Day.

[23] Delaying by almost a week the Soviet troops in front of Änäkäinen provided time for building the new positions in Puuruu.

[23] Near Puuruu lake there is a memorial plate attached on the granite stone with the text "TÄÄLLÄ TAISTELTIIN 9–25.12.1939" ("The fights went on here from 9 to 25 December 1939") to commemorate the Lieksa battles.