Kammala wannan magana: A matsayin marubucin litattafai, Eggen ya fara bugawa ne game da rayuwa da mutuwar Janar Carl Gustav Fleischer, babban kwamandan Norway a Narvik
A shekara ta 1940. Ya kuma rubuta hoton marubucin Agnar Mykle, surukinsa kuma ya rubuta litattafai tare da batutuwa daga tsakiyar zamanin Norway. A cikin 1993 Eggen ya wallafa "Yaron daga Gimle" - labarin tarihin rayuwar ɗan yarinyar Norway a cikin yanayin Nazi. Sakamakon haka, bayan shekara biyu yaran yakin Norway sun sami uzuri na hukuma.