The Finnish Civil War was a conflict for the leadership and control of Finland during the country's transition from a Grand Duchy of the Russian Empire to an independent state. The clashes took place in the context of the national, political, and social turmoil caused by World War I (Eastern Front) in Europe. The civil war was fought between the Reds, led by a section of the Social Democratic Party, and the Whites, conducted by the conservative-based Senate. The paramilitary Red Guards, composed of industrial and agrarian workers, controlled the cities and industrial centres of southern Finland. The paramilitary White Guards, composed of farmers, along with middle-class and upper-class social strata, controlled rural central and northern Finland.
In the years before the conflict, Finnish society had experienced rapid population growth, industrialisation, pre-urbanisation and the rise of a comprehensive labour movement. The country's political and governmental systems were in an unstable phase of democratisation and modernisation. The socio-economic condition and education of the population had gradually improved, as well as national thinking and cultural life had awakened.
World War I led to the collapse of the Russian Empire causing a power vacuum in Finland, and a subsequent struggle for dominance leading to militarisation and escalating crisis between the left-leaning labour movement and the conservatives. The Reds carried out an unsuccessful general offensive in February 1918, supplied with weapons by Soviet Russia. A counteroffensive by the Whites began in March, reinforced by the German Empire's military detachments in April. The decisive engagements were the Battles of Tampere and Vyborg (Finnish: Viipuri; Swedish: Viborg), won by the Whites, and the Battles of Helsinki and Lahti, won by German troops, leading to overall victory for the Whites and the German forces. Political violence became a part of this warfare. Around 12,500 Red prisoners of war died of malnutrition and disease in camps. About 39,000 people, of whom 36,000 were Finns, perished in the conflict.
In the aftermath, the Finns passed from Russian governance to the German sphere of influence with a plan to establish a German-led Finnish monarchy. The scheme was cancelled with the defeat of Germany in World War I and Finland instead emerged as an independent, democratic republic. The Civil War divided the nation for decades. Finnish society was reunited through social compromises based on a long-term culture of moderate politics and religion and the post-war economic recovery.