The Viking Age and Medieval Power

Danish history as a unified kingdom began in the 8th century CE. The Danes were renowned seafarers who, during the Viking Age (c. 800–1050 CE), were major forces in trade, raiding, and colonization across Europe. King Gorm the Old was the first known ruler in the 10th century, and his son, Harald Bluetooth, officially united Denmark and converted the Danes to Christianity around 965 CE. Danish kings, such as Cnut the Great, went on to rule a vast North Sea Empire that included England and Norway in the 11th century. 

In the late Middle Ages, the Kalmar Union (1397–1523) united Denmark, Norway, and Sweden (including Finland) under a single, Danish-dominated monarchy, a high point of Danish influence. 

From Monarchy to Modern State

After Sweden left the Kalmar Union, the Reformation in the 16th century established Lutheranism as the state religion, further centralizing power. A series of devastating wars with Sweden in the 17th century resulted in significant territorial losses, including the permanent ceding of southern Swedish provinces (Skåneland). In 1814, following the Napoleonic Wars, Denmark was forced to cede Norway to Sweden, retaining the Faroe Islands, Greenland, and Iceland as its remaining non-continental territories. 

The absolute monarchy was replaced by a democratic constitution in 1849, establishing a constitutional monarchy. The 19th and early 20th centuries saw the rise of industrialization and democratic reforms, including universal suffrage in 1915. 

The World Wars and Welfare State

Denmark remained neutral in World War I. In World War II, it was occupied by Nazi Germany from 1940 to 1945, though its government initially cooperated to a degree. One of the most notable events of the occupation was the successful rescue of most of the Danish Jewish population to neutral Sweden in 1943. 

In the postwar era, Denmark became a founding member of NATO in 1949 and joined the European Economic Community (EEC), now the EU, in 1973. Throughout the 20th century, the nation developed its comprehensive social welfare state, free healthcare, and education systems, which are central to modern Danish identity and contribute to its ranking as one of the happiest nations on Earth.