He was born in Elverum[1] as a son of physician Christopher Pavels Munthe (1816–1884).
[3] His first major work on military history was released in 1897, and several followed, except in the years when he was a fortress commander.
The first work pertained to military officer Peder von Todderud and the chronicles he wrote during the Great Northern War.
After retiring as a commander, Munthe drifted away from military history, and instead drew his book topics from Medieval Norway themes.
He was also associated with the Norwegian Mapping and Cadastre Authority (then known as Norges Geografiske Oppmåling) during his career, and contributed to newspapers, periodicals as well as the encyclopedias Dansk biografisk lexikon, Norsk biografisk leksikon and Aschehougs konversationsleksikon.