Between 1906 and 1908, Mannerheim led a special mission for the Russian government, collecting intelligence along Russia's border areas in the Far East. His excellent reports made a favorable impression on Tsar Nicholas II, whom he met in 1908. Mannerheim then commanded cavalry units in Poland and was promoted to major general. He saw considerable combat during World War I, mostly commanding cavalry divisions under General Aleksei Brusilov. He took command of the 12th Cavalry Division in the 1915 Galician Campaign and participated in the 1916 Brusilov Offensive. After Romania joined the war, Mannerheim transferred to the Transylvanian Alps. Promoted to lieutenant general in June 1917, he headed VI Cavalry Corps.
Mannerheim opposed the March 1917 revolution that deposed the tsar, and following the Bolshevik Revolution of November 1917, he retired from the Russian army and returned to Finland. He then commanded the White Army in Finland, defeating the Communist Red Guards and freeing Finland of Russian troops. Thereafter, he resigned his command and traveled in western Europe. Appointed regent in December, he returned to Finland. After being defeated in the presidential election of July 1919, he retired from public life and traveled widely, including to India.
Mannerheim returned to public service as minister of defense in 1931. As part of a program of bolstering Finland's defenses, he oversaw construction of what became known as the Mannerheim Line, which held invading Soviet troops at the beginning of the 1939–1940 Finnish-Soviet War (the Winter War). He commanded Finnish forces in the Winter War and in the renewal of fighting with the Soviet Union between 1941 and 1944 (the Continuation War). Advanced to field marshal in 1942, Mannerheim became president of Finland in 1944 and negotiated the armistice with the Soviet Union. He retired for reasons of ill health in 1946 and moved to Switzerland to write his memoirs. Mannerheim died in Lausanne, Switzerland, on 28 January 1951.
Michael Share and Spencer C. Tucker
Mannerheim, Carl G. The Memoirs of Marshal Mannerheim. Trans. Eric Lewenhaupt. New York: E. P. Dutton, 1954.; Screen, J. Mannerheim: The Years of Preparation. London: C. Hurst, 1993.; Upton, Anthony F. Finland in Crisis, 1940–1941. Ithaca, NY: Cornell University Press, 1965.; Warner, Oliver. Marshal Mannerheim and the Finns. London: Weidenfeld and Nicolson, 1967.