He took the Old Norse name Haakon and ascended to the throne as Haakon VII, becoming the first independent Norwegian monarch since 1387. As king, Haakon gained much sympathy from the Norwegian people. Although the Constitution of Norway vests the King with considerable executive powers, in practice Haakon confined himself to non-partisan roles without interfering in politics, a practice continued by his son and grandson. Norway was invaded by Nazi Germany in April 1940.
Haakon rejected German demands to legitimize the Quisling regime's puppet government, and refused to abdicate after going into exile in Great Britain. As such, he played a pivotal role in uniting the Norwegian nation in its resistance to the invasion and the subsequent five-year-long occupation during the Second World War. He became King of Norway when his grandfather Christian IX was still reigning in Denmark, and before his father and elder brother became kings of Denmark.During his reign he saw his father Frederick VIII, his elder brother Christian X, and his nephew Frederick IX ascend the throne of Denmark, in 1906, 1912 (also of Iceland from 1918 to 1944), and 1947 respectively. Haakon died at the age of 85 in September 1957, after having reigned for nearly 52 years. He was succeeded by his only son, who ascended to the throne as Olav V.