Carl Gustaf Emil Mannerheim was born at Louhisaari in Askainen parish on 4 June 1867. After passing the university matriculation examination in 1887, Mannerheim enrolled at the Nicholas Cavalry School in St Petersburg, from which he began his career in the Russian army. During World War I Mannerheim was at first commander of the Independent Guards Cavalry Brigade and then of the 12th Cavalry Division, fighting against the Austrians. The Russian Revolution ended his career in the army of the Emperor and after the October Revolution the fifty-year old lieutenant-general returned to newly-independent Finland, which the waves of the revolution had already reached.

The Finnish government, the Senate, appointed Mannerheim commander-in-chief of the army with the task of its formation and organization. During the Civil War in 1918, when he was promoted general of cavalry, he led the troops of the White government to victory against the Red Guards and Russian troops who had remained in the country. After the final defeat of Germany, the situation in Finland changed and Mannerheim was chosen as regent in December 1918. The following year he confirmed Finland’s republican constitution but lost to K. J. Ståhlberg in the country’s first presidential elections in summer 1919. In 1931 he returned to military duties as chairman of the Defence Council and was promoted field marshal on 19 May 1933.

On the outbreak of the Winter War on 30 November 1939 Mannerheim was appointed commander-in-chief of the defence forces. In autumn 1939, during the negotiations with the Soviet Union, his position had been that, because of the weak state of its defences, Finland ought to try to come to an agreement by partially accepting the Soviet Union’s territorial demands. The wartime activity of Mannerheim, who received the rank of Marshal of Finland on 4 June 1942, was in part also political. His aim was to prevent the country becoming too committed to Germany, which he considered contrary to Finland’s interests. 

During the final phase of the war, on 4 August 1944, parliament elected Mannerheim president of the republic. His task included also the extrication of Finland from the war. Because of his weakened health Mannerheim relinquished all his duties in March 1946. Mannerheim spent his last years quietly in Switzerland, where he died on 28 January 1951.