The Mannerheim family descends from a German businessman and mill owner from Hamburg, Hinrich Marhein (1618–1667), who emigrated to Gävle in Sweden and changed his name to Henrik. His son Augustin Marhein changed his surname to Mannerheim, and was raised to the nobility in 1693. His son, an artillery colonel and a mill supervisor, Johan Augustin Mannerheim, was raised to the status of Baron at the same time as his brother in 1768. The Mannerheim family came to Finland, then an integral part of Sweden, in the latter part of 18th century.
Mannerheim was born in Helsinki. In 1886, he joined the Royal Military Academy. He quickly rose through the ranks to become Armed Forces Chief in 1905. In 1906, he joined the Parti Skandinavien and was elected president of Scandinavia in 1909, a post he would hold until 1918. He would remain as Armed Forces Chief until 1940.