James Stewart wasn't impressed with the script, but accepted the role of Grant McLaine because he believed the part would allow him to show off his skills as an accordion player. However, all of his accordion playing was re-recorded by a professional prior to the movie's release.
James Neilson replaced Anthony Mann as director when Mann walked off the picture after a falling out with James Stewart.
Anthony Mann refused to direct the film, saying nobody would understand it. He also said he believed the script was bad and that Audie Murphy - who was 5'5" - would not be believable as the brother of James Stewart, who was 6'3". After the film opened to poor reviews and business, Stewart never spoke to Mann again.
Filmed in Silverton, Colorado (called Junction City in the movie) using the Durango & Silverton Narrow Gauge Railroad.
First feature produced in the United States in the Technirama widescreen process, developed by the Technicolor Corp. Many of the credits were rendered in the style of the Technirama trademark.
In August 1957, this film was being being shown on a double bill with The Delinquents.
The real name of the Utica Kid turns out to be Lee, thus the names of the warring brothers are Grant and Lee, just like the opposing generals in the Brothers' War (the American Civil War)
This was originally intended to be the sixth Western combining the talents of actor James Stewart and director Anthony Mann (they had also done three non-Westerns together), but Mann pulled out of the project because he wasn't impressed with war hero-turned-actor Audie Murphy. Stewart and the director would never make another picture together.