The Columbia Encyclopedia, Sixth Edition. 2001-07.
Kalmar Union
combination of the three crowns of Denmark, Sweden, and Norway, effected at Kalmar, Sweden, by Queen Margaret I in 1397. Because the kingship was elective in all three countries, the union could not be maintained by inheritance. Nationalist forces used the election procedure to modify terms of the union. Margarets successors controlled Sweden only for brief periods; the accession (1523) of Gustavus I as king of Sweden dissolved the union. The union of Denmark and Norway lasted, however, until 1814.