Philosophy Kand., U. Stockholm, 1976. Company brigade United Nations, Kongo, Zaire, 1961-1962, Company battalion, Cyprus, 1964. Aide-de-camp to Swedish King, Royal Court, Stockholm, 1957-1973, lord in waiting, 1974-1986.
Governor Gripsholm Castle and Stromsholm Palace, 1975-1983.
Consultant Palace of Drottningholm, 1983-1985.
He also commanded Swedish forces on Cyprus in 1964. Later, he served as adjutant to Gustaf VI Adolf of Sweden. He passed his studentexamen in 1934 and the reserve officer"s exam in 1936 and officer"s exam in 1940.
Wærn became an officer at Värmland Regiment (I 2) in 1941.
During World World War II he served as commander of a jäger platoon at the Norway–Sweden border. Wærn served at the Army Staff in 1955 and at Västerbotten Regiment (I 20) in 1956 and became major the same year.
He was a colonel and commander of the twelfth and fourteenth Swedish United Nations battalion in Congo from 1961 to 1962. At the same time, he was brigade commander of the Swedish, Indian and Irish troops in southern Katanga, which was part of the United Nations Operation in the Congo (UN Operation in the Congo) from June 1961 to May 1962.
Wærn was the section chief of the IV Military Commanding Staff in 1962 and was commander of the Swedish United Nations Battalion in Cyprus in 1964, part of the United Nations Peacekeeping Force in Cyprus.
He was infantry commander of the Stockholm Coastal Artillery Defense (Stockholms kustartilleriförsvar) in 1966. In 1974 he was appointed cabinet chamberlain. Wærn continue to be active at the court as governor of Gripsholm Castle and Strömsholm Palace from 1975 to 1983.
In 1976 he received a Bachelor of Arts degree.
In spring 1998, the television program Röda rummet did a viewing poll about the century"s most significant Swedish books Wærn"s book about Katanga was placed in 84th place out of 100 titles.
Wærn was a member of the Samfundet SHT and of the Charles John Association (Karl Johans förbundet).
Married Lissie Margrete Ehnstrom, September 28, 1939. Children: Stina, Olof, Jurkind, Peder(deceased), Lotta.