Transit of German troops through Finland and Sweden Union immediately requested a similar but more far-reaching concession from Finland, which invited the Third Reich to trade similar transit rights through Finland in return for weaponry lacked by the Finns. This was the first significant proof of a changed, more favorable, German policy vis-à-vis Finland, that ultimately would put Finland in a position of co-belligerence with Nazi Germany in the Continuation War against the Soviet Union (June 25, 1941 – September 4, 1944). After Denmark and Norway were invaded on April 9, 1940, Sweden and the other remaining Baltic Sea countries became enclosed by Nazi Germany and the Soviet
Finland–Russia border most of which were Savonians. After the Finnish War, the Treaty of Fredrikshamn converted all of Finland from Swedish territory to a Russian possession, the Grand Duchy of Finland. The Finnish–Russian border was moved back to the pre-1721 location, so that the Grand Duchy gained the so-called "Old Finland", territories previously held by Sweden, in 1812. After Finland became independent in 1917, there was the Finnish Civil War in 1918, and even after this war, the Russian Civil War continued. Finnish activists often crossed the border into Soviet territory in order to fight in the "heimosodat", wars aiming at Finnish