The character named "Hawkwood" was probably named after Sir John Hawkwood (1320-1394) who was an actual historical figure. Hawkwood commanded a band of condottiere, "The White Company", in Italy in the 14th century.
The movie was greatly inspired by The Wild Bunch (1969) (which also dealt with two former allies who become enemies), Vera Cruz (1954) and The Crimson Pirate (1952). Suggested titles for the movie were 'The Mercenaries' and 'God's Own Butchers' before settling on 'Flesh + Blood' (which was the title of a recent Roxy Music album at the time).
Paul Verhoeven decided for the first time not to storyboard the entire movie and adopt a more improvisational style of directing; a decision that he quickly regretted, given the enormously complex nature of the production.
The movie was awarded two prizes at the Dutch Film Festival (Best Picture and Best Director), but several jury members publicly attacked this decision afterwards, stating that the vote had not been unanimous.
The movie was Paul Verhoeven's reaction to the many movies that, in his view, overly romanticized the Middle Ages; he wanted to show it as a period where brutality, disease, poverty and hardship were common, and a natural death was a rare thing.
Paul Verhoeven wanted to explore the idea of a confrontation between two allies who had become enemies in this movie. However, the studio wanted a bigger part for the character of Agnes and more focus on the love story, so the audience could better identify with the main characters. The feud between Martin and Hawkwood was therefore pushed to the background, a decision that Verhoeven later regretted.
Orion Pictures kept asking Paul Verhoeven for a war movie like his previous film Soldier of Orange (1977). Since he did not have one readily available, he and screenwriter Gerard Soeteman hastily produced a brief story outline concerning a medieval group of mercenaries, a project that they had conceived more than ten years before, but abandoned to do other movies.
The production was plagued by adversities. There was great animosity among the Spanish, American and Dutch crew and cast members; actors were using alcohol and drugs on the set, while wind, heavy snowfall and cold often disrupted filming, causing the movie to go over budget. Director Verhoeven would later call it the worst filming experience of his life, one that almost made him consider to quit making movies altogether.
This was literally Paul Verhoeven's last project in the Netherlands for two decades. He attended the Dutch film festival, during which the film premiered, and he took a plane to the USA the very next morning, in order to direct his American debutRoboCop (1987).
There was so much competition for screen presence among the actors, that some of them started to call the movie 'Flesh + Blood + Elbows', in the sense that some cast members would literally use their elbows to push others out of frame.