Why did Stanley Kubrick have less creative control over Spartacus than his other films?

Stanley Kubrick had less creative control over Spartacus (1960) primarily because he was brought in as a replacement director after the original director, Anthony Mann, was fired.1

Unlike his other projects, where Kubrick typically maintained a hands-on approach to all aspects of production—including writing, cinematography, and editing—Spartacus was a large-scale studio production where he was hired to execute a project already in motion. The film was produced by its star, Kirk Douglas, who held significant authority over the production, including the hiring of screenwriter Dalton Trumbo. Consequently, while the film was a critical success, it remained the most anonymous of Kubrick’s works, as he lacked the total creative autonomy he exercised over his own independent or self-initiated films.12