Sigurd Jonsson
Norwegian regent
Sigurd Jonsson (1390s – December 1452) was a Norwegian nobleman, knight and the regent of Norway during two interregnums in the mid-15th century.
Background
Sigurd Jonsson was born at some point between 1390 and 1400. He was the son of the Swedish nobleman Jon Marteinsson (1340 – c. 1400) and Agnes Sigurdsdotter. Agnes was the great-granddaughter of King Haakon V of Norway through his illegitimate daughter, Agnes Haakonsdatter (1290–1319) and Havtore Jonsson (1275–1320). Sigurd Jonsson was the grandson and the heir of Sigurd Havtoresson (1315–1392), one of the two sons of Agnes Hakonardottir.
At the time of Sigurd's birth, Jon Marteinsson was a resident in Norway and a member of the Norwegian Council of the Realm (riksrådet). Sigurd grew up at the family's estate in Sudreim (modern Sørum), east of Oslo. He had two sisters, Catherine and Ingeborg, and a brother, Magnus, but his brother did not survive to reach maturity. Sigurd therefore inherited his father's estates, and also great landholdings from his mother's relatives.
Career
Sigurd is first mentioned as a member of the Norwegian Council of the Realm in 1434.
Begin with the source’s own compact description: “Sigurd Jonsson” is norwegian regent. The dossier treats that line as a proposition to test through Sigurd, Jonsson and Norwegian, not as a finished interpretation.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Aug 2, 2026. The linked authority identifier is Q6327151. None of the 1 selected statements returned an explicit reference. The first chronological checks are 1452, 1390, 1400 and 1340.
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This entry incorporates text from “Sigurd Jonsson” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.