Denmark-Norway was a historical union between the Kingdom of Denmark and the Kingdom of Norway that lasted from 1380 to 1814. The union began when King Haakon VI of Norway married Margaret I of Denmark, leading to a shared monarchy. Although both kingdoms maintained their own laws and customs, they were ruled by a single monarch. The union faced challenges, including conflicts and differing interests between the two nations. It ended after the Napoleonic Wars, when Norway was ceded to Sweden in the Treaty of Kiel in 1814. This marked the beginning of Norway's journey towards independence.