Munch's first great achievement, with Rudolph Keyser, was their three volumes of Norges Gamle Love, edited after a two-year research visit to Copenhagen. In 1837, he became lecturer in history at the University of Oslo and in 1841 became a professor of history. In 1857, after producing numerous publications, he received a large grant for archives research in Rome and lived there from 1859 to 1861. Munch served as Norway's national archivist from 1861 to 1863. He was one of the first non-Catholics to be allowed into the archives of the Vatican. He took extensive notes from the volumes of papal letters, and sometimes drew accurate facsimiles of the texts. His research there was useful in his main work, Det norske Folks Historie, in eight volumes, and he sent his notes home to the Royal Archives in Christiania. Among the theories he is remembered for is the theory on immigration to Norway, in which he developed work done by Rudolf Keyser. On a trip back to Rome to fetch his family, who had remained there for a while, he died from a stroke, and was buried in the Protestant cemetery in Rome.
In this work, Munch translated the 3rd Chronicle from a Codex transferred to the British Museum. The manuscript is the only known copy of this Codex. In any event, Munch translated runic characters and added historical notes to lend light upon the writings, and using previous works on the history of Scottish and Icelandic Isles to aid in the presentation of the translated material.
Peter Munch had racial thoughts on certain peoples, e.g. Finns and Hungarians. He despised Finns and claimed that they cannot have an independent country because of their low state of civilization, as he claimed. Peter Munch claimed in his article on Finnish nationality in 1855, that Finns and Hungarians must have a human race of their own.
Selected works
Norges, Sveriges og Danmarks Historie til Skolebrug
Norges Historie i kort Udtog for de første Begyndere
Nordens gamle Gude- og Helte-Sagn i kortfattet Fremstilling
Verdenshistoriens vigtigste Begivenheder
De nyeste Tiders Historie
Fortegnelse over de mest befarede Landeveie og Reiserouter saavel mellem Stæderne, som Landdistricterne i Norge
Det oldnorske Sprogs eller Norrønasprogets Grammatik
Underholdende Tildragelser af Norges Historie
Nordmændenes Gudelære i Hedenold
Det gotiske Sprogs Formlære
Kortfattet Fremstilling af den ældste norske Runeskrift
Om Skandinavismen
Historisk-geographisk Beskrivelse over Kongeriget Norge i Middelalderen
