has just test-flown is a "death trap" with weak struts, von Klugemann sees a way out and tells Stachel, "Let's see some real flying". Stachel's aerobatics causes the aircraft to break up and crash. Cast Cast notes: The casting of George Peppard in the mainly international ensemble cast was considered a "safe" choice, as he was establishing a reputation for leading roles in action films. Although youthful looking, at 37 years of age, he was much older than the Stachel depicted in the novel. Peppard wanted to create an "authentic" performance and learned to fly, earned a private pilot's license and did some of his own flying in the film, although stunt pilot Derek Piggott was at the controls for the under-the-bridge scene. Novel Jack Hunter's debut novel was published in 1964. The New York Times called it "entertaining". The novel was optioned by 20th Century Fox, which in October 1964 assigned Ben Barzman and Basilio Franchina to write the script. In December, Fox announced that it would make the film the following summer. Compared to film The film differs from the book on which it is based both in the plot and the portrayal of the characters. Some of the differences are: Stachel: The movie portrays Stachel initially as an idealistic, humble and naive man who evolves into someone willing to do whatever it takes to get his way. He is also depicted as being insecure about his lower-class background and desires to prove himself an equal aviator and man to the aristocrats by earning the Blue Max. The vain attempt by Stachel to confirm his first kill occurs only in the film. There is also no confrontation with Heidemann, who takes a swift dislike to Stachel over claiming aircraft that Willi had shot down. Stachel was played by the 37-year-old George Peppard, in stark contrast to the 19-year-old character of the novel. From the beginning of the novel, Stachel is a deeply troubled alcoholic with a penchant for lying. Obsessed with earning the last of the new Fokker D.VIIs, he kills Willi to obtain it. In the novel, Heidemann exhibits an immediate favouritism toward the newcomer and credits Stachel with his first victories, and Kettering, the squadron adjutant, refuses to comply until Heidemann orders him to do so. At the end of the novel, Heidemann reveals that he has been secretly boosting Stachel's achievements as part of an