The latter half of the 1930s started with the Second Italo-Abyssinian War, which Kullmann protested. For this he was expelled from Italy, where he had travelled in 1935. He issued the book "Hjelp din bror, etioperen" ("Help Your Brother, the Ethiopian") in Norway in 1938. In 1940 Norway was invaded by Germany, involving Norway in World War II. Kullmann subsequently bicycled around Norway to agitate for pacifism.