Amidst the German occupation of Belgium during World War II, Hergé had accepted a position working for , Belgian's largest Francophone daily newspaper.
The Secret of the Unicorn was the first of The Adventures of Tintin which Hergé had collaborated on with Van Melkebeke to a significant degree; biographer Benoît Peeters suggested that Van Melkebeke should rightly be considered the story's "co-scriptwriter".