The Winter War ended in the Moscow Peace Treaty in 13.3.1940. At that point the foreign voluntary working groups were only just on their way to Finland when the demobilization of foreign soldiers who had voluntarily served as a part of Finland’s troops had already begun. The fortifying works of the Luumäki line was envisaged for the Swedish and Norwegian voluntary fortifying workers. Picture above is from the leader Swedish voluteer working, Fred Hansens photos. Can also be found from a book En mur mot öst, svenska arbetskåren i Finland – Eric Björklund. Kohti Salpalinjaa – Eric Björklund.
Fortifying-work during the Winter War wasn’t unfamiliar to the local people of Kotka either. The fortifying of the islands of Eastern Suomenlahti had been ongoing through the entire duration of the war, with additional work being imposed on the 10th day of December when the navy had received an order to fortify the line of Kymi river (Kymijoki). From Gulf of Finland to the Kouvola area. The so-called Tavastila’s area from the beach to Juurikorpi had been under fortifying with machinegun & crew dugouts since the end of January in 1940. In the same time navy was workin around Utti area also.
After the Winter War ended the area of Karjalan Isthmus along with its fortresses, Mannerheim Line, was left under the custody of the Soviet Union. The retreat of the Finnish field army to behind the new border set by the Moscow’s peace caused the fortifying of Luumäki line to be interrupted and the fortifying working groups to be relocated to the western side of Kymi river(Kymijoki). The travel of the Kymijoki-line was simultaneously re-lined under Headquarter’s pioneer commander Unio Sarlin. At the southern end of the defenceline it was designated to travel along the western bank of the eastern river fork of Kymijoki.
The working groups started their immediate transferring to their work-areas. Arthur Nikander was designated as the chief and high-engineer of the zone from Anjala all the way to Kotka island. Nikander arrived on his zone on the same day as the first Swedish builders on 15.3.1940. The finnish working groups and the Norwegian fortifying working group were on their upcoming worksite on 17.3. And so 5000 men came to momentarily work on Nikanders zone.
The Norwegians lodged on the island of Kotkansaari at a local girl’s vocational school. They began the mining of two mountain dugouts, a cave/tunnels and trenches which were set to be located two kilometers to North from Kotka. The work didn’t proceed without problems as the Norwegian’s equipment never arrived and even the Swedish tools were stuck traveling back and forth between railroads. The Swedish workers set camp in Sutela and began to work on of mining Lankila’s cave/tunnel along with digging the trenches.
The biggest working group around Kotka was the Kaitera’s workgroup that consisted entirely of finns. The responsibility area of the working group reached from Jumalniemi to Parikka. At its best the working group consisted of around 2000 fortifying workers, which was over double the amount of people in both the Norwegian and Swedish groups combined. Kaitera’s area also had over double the amount of caves/tunnels planned on it, for a total of 6 caves/tunnels. The Finnish working group was also assigned different types of fortresses that the foreign groups didn’t get to work on, such as the mining of rocks to anti-tank obstacles. At most over 15 000 men worked on the line that reached from Kotka to Utti(near Kouvola).
The work on the Kymijoki-line didn’t continue for long, as the fortifying work was ordered to be stopped as early as 6.4. The equipment, caves, fortresses and other already started projects were commanded to be finished. The Norwegians left to return to their own country couple days after 9.4 when Germany had launched operation Weserübung and attacked to Norway and Denmark. The Swedish moved over to Klamila in Virolahti on 4.4. to work on the new planned defenceline called Salpaline. Naturally the Finnish working groups also shrunk fast as they consisted of work-obliged people who had been commanded to be demobilized beginning on 8.4.
The caves build along the Kymijoki-line were admitted to Kotka’s branch of the Finnish navy. They were used during the Continuation War as ammunition- and fuelstorages. The navy was especially interested in the Swedish-made cave of Lankila and ordered the mining of the cave to be restarted in order to accumulate more extra storage space. The cave of Lankila was envisaged to the use of the military staff during the Continuation War. The smaller cave in Kierikkala was used Kymi’s air surveillance center during the beginning of the Continuation War, but as the winter neared the air surveillance center was moved to the larger cave of Lankila.