From 10,000 to 1500 B.C. , the population of present-day Denmark evolved from a society of hunters and fishers into one of farmers. Called Jutland by the end of the 8th century, its mariners were among the Vikings, or Norsemen, who raided western Europe and the British Isles from the 9th to 11th century.
The country was Christianized by Saint Ansgar and Harald Blaatand (Bluetooth)—the first Christian king—in the 10th century. Harald's son, Sweyn, conquered England in 1013. Sweyn's son, Canute the Great, who reigned from 1014 to 1035, united Denmark, England, and Norway under his rule; the southern tip of Sweden was part of Denmark until the 17th century. On Canute's death, civil war tore apart the country until Waldemar I (1157–1182) reestablished Danish hegemony in the north.
In 1282, the nobles won the Great Charter, and Eric V was forced to share power with parliament and a Council of Nobles. Waldemar IV (1340–1375) restored Danish power, checked only by the Hanseatic League of north German cities allied with ports from Holland to Poland. Denmark, Norway, and Sweden united under the rule of his daughter Margrethe in 1397. But Sweden later achieved autonomy and in 1523, under Gustavus I, independence.
Denmark supported Napoléon, for which it was punished at the Congress of Vienna in 1815 by the loss of Norway to Sweden. In 1864, the Prussians under Bismarck and the Austrians made war on Denmark as an initial step in the unification of Germany. Denmark was neutral in World War I.