Since 1935, Lange studied German, history, philosophy, anthropology, music and art at the University of Kiel.
Lange's enslavement interrupted his academic career and left him in permanently poor health.
Upon the recommendation of Wolfgang Krause, Lange was in 1950 made an assistant of Ulrich Pretzel [de] at the University of Hamburg.
Upon the recommendation of Krause and Eduard Neumann, Lange habilitated at Kiel in 1955 with a thesis on Christian Skaldic poetry.
In the 1960s he worked with Herbert Jankuhn and Hans Fromm [de] on the third edition of Rudolf Much's commentary on Germania.