Earliest rulers invaded Britain; King Canute, who ruled in London 1016-1035, was most famous. The Valdemars furnished kings until the 15th century. In 1282 the Danes won the first national assembly, Danehof, from King Erik V.

Most redoubtable medieval character was Margaret, daughter of Valdemar IV, born 1353, married at 10 to King Haakon VI of Norway. In 1376 she had her first infant son Olaf made king of Denmark. After his death, 1387, she was regent of Denmark and Norway. In 1388 Sweden accepted her as sovereign. In 1389 she made her grand-nephew, Duke Erik of Pomerania, titular king of Denmark, Sweden, and Norway, with herself as regent. In 1397 she effected the Union of Kalmar of the three kingdoms and had Erik VII crowned. In 1439 the three kingdoms deposed him and elected, 1440, Christopher of Bavaria king (Christopher III). On his death, 1448, the union broke up.

Succeeding rulers were unable to enforce their claims as rulers of Sweden until 1520, when Christian II conquered Sweden. He was thrown out 1522, and in 1523 Gustavus Vasa united Sweden. Denmark continued to dominate Norway until the Napoleonic wars, when Frederick VI, 1808-1839, joined the Napoleonic cause after Britain had destroyed the Danish fleet, 1807. In 1814 he was forced to cede Norway to Sweden and Helgoland to Britain, receiving Lauenburg. Successors Christian VIII, 1839; Frederick VII, 1848; Christian IX, 1863; Frederick VIII, 1906; Christian X, 1912; Frederick IX, 1947; Margrethe II, 1972.

Early kings ruled at Uppsala, but did not dominate the country. Sverker, c1130-c1156, united the Swedes and Goths. In 1435 Sweden obtained the Riksdag, or parliament. After the Union of Kalmar, 1397, the Danes either ruled or harried the country until Christian II of Denmark conquered it anew, 1520. This led to a rising under Gustavus Vasa, who ruled Sweden 1523-1560, and established an independent kingdom. Charles IX, 1599-1611, crowned 1604, conquered Moscow. Gustavus II Adolphus, 1611-1632, was called the Lion of the North. Later rulers: Christina, 1632; Charles X Gustavus, 1654; Charles XI, 1660; Charles XII (invader of Russia and Poland, defeated at Poltava, June 28, 1709), 1697; Ulrika Eleanora, sister, elected queen 1718; Frederick I (of Hesse), her hus­band, 1720; Adolphus Frederick, 1751; Gustavus III, 1771; Gustavus IV Adolphus, 1792; Charles XIII, 1809. (Union with Norway began 1814.) Charles XIV John, 1818 (he was Jean Bernadotte, Napoleon's Prince of Ponte Corvo, elected 1810 to succeed Charles XIII); he founded the present dynasty: Oscar I, 1844; Charles XV, 1859; Oscar II, 1872; Gustavus V, 1907; Gustav VI Adolf, 1950; Carl XVI Gustaf, 1973.

Overcoming many rivals, Harald Haarfager, 872-930, conquered Norway, Orkneys, and Shetlands; Olaf I, great-grandson, 995-1000, brought Christianity into Norway, Iceland, and Greenland. In 1035 Magnus the Good also became king of Denmark. Haakon V, 1299-1319, had married his daughter to Erik of Sweden. Their son, Magnus, became ruler of Norway and Sweden at 6. His son, Haakon VI, married Margaret of Denmark; their son Olaf IV became king of Norway and Denmark, followed by Margaret's regency and the Union of Kalmar, 1397.

In 1450 Norway became subservient to Denmark. Christian IV, 1588-1648, founded Christiania, now Oslo. After Napoleonic wars, when Denmark ceded Norway to Sweden, a strong nationalist movement forced recognition of Norway as an independent kingdom united with Sweden under the Swedish kings, 1814-1905. In 1905 the union was dissolved and Prince Charles of Denmark became Haakon VII. He died Sept. 21, 1957; succeeded by son, Olav V. Olav V died Jan. 17, 1991; succeeded by son, Harald V.