Why did Norway come under the influence of Denmark and Sweden after the Middle Ages?

Norway’s long-term political subordination to Denmark and eventual union with Sweden were driven by a combination of demographic collapse, institutional weakness, and shifting geopolitical alliances.

Union with Denmark

The foundation for Norway’s union with Denmark was laid in the late 14th century under Margaret I, culminating in the Kalmar Union in 1397, which united Norway, Denmark, and Sweden under a single monarch. Norway’s ability to resist Danish dominance was severely compromised by the Black Death, which decimated the population and the local aristocracy, leaving the country without a strong national council to assert its interests. Consequently, administration became centralized in Copenhagen, and in 1536, Norway was formally declared a Danish province.1234

Transition to Sweden

Norway remained under Danish rule until the Napoleonic Wars. Following the Treaty of Kiel in 1814, Denmark was forced to cede Norway to Sweden as compensation for Sweden's loss of Finland to Russia. Norway resisted this forced transfer, leading to a compromise that established a royal union with Sweden that persisted until 1905.5