Some of the Salpa Line objects dates back to the Winter War. In Lieksa "Viisikon Salpalinja etusema" was started to be built already during the pre-Winter War extra military training period . The name "Viisikko" refers to the name of the village and can be translated as "The Five". The other names of the village are Hattuvaara (of Lieksa) or just Hattu (a Hat). The battles in Hattu are related to the battles of Lieksa from the very first war day, 30 November 1939 to 27 December 1939. The Soviet forces attacked against the Viisikko positions on 9 December 1939 and it had to start to withdraw on Christmas Day.