By the time Eduard Galić set out to direct
Black Birds, his debut feature film, he was already an established television director and an author of award-winning documentaries. He developed an interest in a screenplay written by
Grgo Gamulin, Galić's former father-in-law, that drew heavily on his personal experiences in World War II. As a long-time leftist, Gamulin spent the entire war imprisoned by the regime of the
Independent State of Croatia. Facing the threat of imminent execution, on 17 April 1945 he managed to escape from the train transporting the prisoners from
Lepoglava to
Stara Gradiška. Galić secured funding for the film and, after negotiations with
Jadran Film fell through, he and
Fadil Hadžić founded Most, an independent production collective. The arrangements were made to produce
Black Birds and Hadžić's
Protest in partnership with , a Slovene production company. Galić's work on the screenplay created a conflict with Gamulin. While the Gamulin's original work was a straightforward action drama, Galić preferred the then highly influential
auteur film. Together with
Zoran Tadić, the assistant director, and
Petar Krelja, Galić developed a new outline of the film in which three central characters were a psalm-quoting Ustasha lieutenant (Šovagović), an engineer tasked with blowing up the bridge (Mirić), and an enigmatic prisoner (Šerbedžija, in his first major film role). Gamulin felt that the new version of the screenplay had nothing to do with his original, and asked for his name to be removed from the credits. In the end, Gamulin was credited for the story, while the screenplay credits were omitted entirely. ==Reception==