[2] During the Norwegian campaign in spring 1940 - Kavli from 9 April to 5 May - joined Major Reidar Holtermann together with over other 200 volunteer soldiers in The Battle of Hegra.
After the liberation of Norway, he worked for the National Museum of Art, Architecture and Design in Oslo from 1950 to 1961.
Other important works include Norwegian Architecture, Past and Present (1958), Norges festninger: fra Fredriksten til Vardøhus (1987) and 25 år på kongens slott (1992).
Karl H. Brox, Kampen om Hegra, Gyldendal Norsk Forlag, 1988.
Guthorm Kavli, Hegra festning (in På kongens slott, pages 21–28 ), Chr.