Finnish Civil War: The Red Guard rebels seize control of the capital, Helsinki; members of the Senate of Finland go underground.

The Finnish Civil War was a civil war in Finland in 1918 fought for the leadership and control of the country between White Finland and the Finnish Socialist Workers' Republic during the country's transition from a grand duchy ruled by the Russian Empire to a fully independent state. The clashes took place in the context of the national, political, and social turmoil caused by World War I in Europe. The war was fought between the Red Guards, led by a section of the Social Democratic Party with backup of the Russian bolsheviks and the White Guards of the senate and those who opposed socialism, with major assistance by the German Imperial Army, along the German goal to control Fennoscandia. The paramilitary Red Guards, which were composed of industrial and agrarian working class people, controlled the cities and industrial centres of southern Finland. The paramilitary White Guards, which consisted of land owners and the middle and upper class Finns, controlled rural central and northern Finland, and were led by General C. G. E. Mannerheim.

The Red Guards were the paramilitary units of the labour movement in Finland during the early 1900s. The Red Guards formed the army of Red Finland and were one of the main belligerents of the Finnish Civil War in 1918.

Helsinki is the capital and most populous city in Finland. It is on the shore of the Gulf of Finland and is the seat of southern Finland's Uusimaa region. About 690,000 people live in the municipality, with 1.3 million in the capital region and 1.6 million in the metropolitan area. As the most populous urban area in Finland, it is the country's most significant centre for politics, education, finance, culture, and research. Helsinki is 80 kilometres (50 mi) north of Tallinn, Estonia, 400 kilometres (250 mi) east of Stockholm, Sweden, and 300 kilometres (190 mi) west of Saint Petersburg, Russia.