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(count of Södermere). Born June 26, 1583, on the family estate in the län (county) of Uppsala; died Sept. 7, 1654, in Stockholm. Swedish statesman. Chancellor (1612–54) during the reigns of Gustavus II Adolphus and Christina.
Oxenstierna acted in the interests of the aristocratic oligarchy and successfully limited royal power through the formation of an aristocratic riksrâd (council of state). He helped carry out administrative and judicial reforms that extended the privileges of the nobility. He also assisted nobles in acquiring state lands. After the death of Gustavus II Adolphus in 1632, he virtually controlled Swedish politics until Christina came of age in 1644. The commander of the Swedish army on the Rhine, he created the League of Heilbronn to unite Protestant German princes (1633). After a series of Swedish defeats in the Thirty Years’ War (1618–48), he actively encouraged France to enter the war.