During the occupation of Norway by Nazi Germany, Sund was fired for anti-German sentiments. He was replaced by Jørgen Nordvik in February 1941. On 12 April, three days after the German invasion, Sund had signed radio broadcast announcements which quoted the Hague Conventions on the laws of war, together with police chief of Oslo Kristian Welhaven and mayor of Oslo Trygve Nilsen. The same announcements warned that francs-tireurs taking part in irregular fighting would be punishable by death in a court-martial. The concern of Welhaven and the other dignitaries was that Norwegians would not know the regulations of the Hague Conventions nor understand the concept of being francs-tireurs, and be then court martialled by the Germans