His name is now a term that means traitor. That’s because after two decades of working for the Norwegian government in various roles, he collaborated with Hitler and the Nazi party, welcomed the German occupation of his country.
Research:

SYMHC Classics: Gustave Courbet
40:51

Behind the Scenes Minis: Oh, Kropotkin!
17:28

Peter Kropotkin's Mutual Aid, Part 2
49:57