As part of Germany's support of Finland and its newly declared parliamentary government, German troops wrest control of Helsingfors (Helsinki) from the Red Guard, an army of Finnish supporters of the Russian Bolsheviks, on April 13, 1918.
Finland, under Russian control since 1809, took the opportunity of the upheaval in Russia in 1917 (including the abdication of Czar Nicholas II in March and the rise to power of Vladimir Lenin and his radical socialist followers, the Bolsheviks, in November) to declare its independence in December of that year. Almost immediately, however, conflict broke out within Finland between radical socialists—supporters of the Bolsheviks in Russia—and anti-socialists within the government. In late January 1918, the radical socialist Red Guard launched a rebellion, terrorizing and killing civilians in their attempt to spark a Bolshevik-style revolution. A bitter struggle ensued as the Whites (as government troops were known) under the command of Baron Karl Gustav Mannerheim sought to drive the Reds out of Finland.
On April 3, 1918, German troops sent by Kaiser Wilhelm II landed in Finland to aid Mannerheim's White army. Ten days later, the Germans captured Helsinki alongside Mannerheim and his force of 16,000 men; they did the same in Viborg by the end of the month. A major victory by the Germans and the White Finns at Lahti on May 7 ended the Finnish civil war.
Germany's close ties with the nascent Finnish government reached a new level in October 1918, when conservative forces in Finland decided to establish monarchal rule in the country, giving the throne to Frederick, a German prince, in the waning weeks of World War I. By the time the Central Powers appealed for an armistice one month later, however, Kaiser Wilhelm himself had abdicated and it seemed certain that the victorious Allies would not look kindly upon a German prince on the Finnish throne. Frederick abdicated on December 14. The Treaty of Versailles, signed in June 1919, recognized Finland's hard-won independence; that July, the Finnish parliament adopted a new republican constitution, and Kaarlo J. Stahlberg, a liberal, was elected as the country's first president.