Hitler had his eye on France — but first he needed to secure his eastern flank from a possible Russian invasion. Russia, for their part, was only too happy to have Germany occupy the west, as long as Russia could have the east. So a deal was struck, and Hitler took France, while Russia invaded Finland. The Winter War was Pyrrhic victory for the Russians: they took several portions of Finland, but failed to annex the entire country. What remained of the Finnish army then joined Hitler in the fight against the USSR.
On this day, September 19, in 1944, Finland signed a second armistice with Russia, ceding again the territories it ceded in the first time, along with several new ones. Finland also agreed to outlaw the Nazi party, legalize the Communist one, and join Russia in the fight against Germany.
With German troops still on Finnish soil after the armistice, Finland was put in the unenviable position of fighting with its new allies against their former ones. Finland originally agreed on an informal timetable for a withdrawal, but Russia pressed the issue, forcing Finland to intensify their attacks. After the war, however, Russia withdrew troops from the non-occupied territories, remembering the heavy casualties they suffered in the first attack.