Perhaps the most praised element of the production was the score by John Barry, then most famous for his "James Bond" scores. In the new millennium, it was still regarded as one of his best scores. In a project to prepare a special CD release of the soundtrack, it was discovered that the complete original session recordings were either lost or destroyed.
The Captain (Sir Michael Caine) refers to the sack of Magdeburg having occurred twelve years previously. The sack took place in 1631, so the events of this movie occur in 1643 to 1644.
American Broadcasting Company's feature production arm, ABC Pictures, intended this to be their break-out prestige production. With their already existing distribution deal with the Cinerama Releasing Corporation, they decided to shoot this movie in the expensive Todd-AO process. It opened as a roadshow presentation in Cinerama venues. The returns were disappointing. The roadshow release was expanded to venues that could show 70mm "flat" prints. With more disappointing returns, this movie quickly went into general release with 35mm anamorphic prints. This movie became a phenomenal box-office disaster. It reportedly grossed less than twenty percent of its production cost. With millions of dollars in losses, ABC Pictures ceased production in 1972.
The Captain changes sides at least once during the war. To have participated in the sack of Magdeburg, he must've fought with the Imperialists. At the end of this movie, he joins the army fighting against the Imperialists. Such fickle behavior was far from uncommon amongst mercenaries of the period.
Sir Michael Caine's character is only ever called "The Captain", and is never known by any personal name.