カール・グスタフ・エミール・マンネルヘイム
In 1917, he joined the white movement and served on the staff of White Finnish leader, Carl Gustaf Emil Mannerheim during the Russian Civil War. He was subsequently a staff officer in the North Western Army of General Yudenich. After the end of the Civil War Prince Sergei settled in England and died in Tonbridge, where he befriended Denton Welch, in 1951.