Taking part as a soldier in the Norwegian Campaign, and subsequently in organising of resistance against the German occupation of Norway, he then initiated a diplomatic career.
In 1940 he volunteered as a soldier in the Winter War in Finland, and after the German invasion in Norway he fought in the Norwegian campaign.
[1] He was among the pioneers of the resistance organization Milorg from 1940 to 1942, serving for a short period as secretary-general ("Stor O") in the central operative leadership.
He was stationed as legation secretary in Lisbon in 1946, and assumed a position in the Ministry of Foreign Affairs in 1948.
[1] Hansson's war decorations include the Defence Medal 1940–1945 with rosette, and the British King's Commendation for Brave Conduct.