Archie Mayo Replaced Fritz Lang - Why?

According to Patrick McGilligan's "Fritz Lang: The Nature of the Beast", Lang exaggerated a gall stone complaint to get off a picture he'd been assigned to but didn't want to do.

And the reason he didn't want to do it? He was assigned at very short notice (while still doing promotion for "Man Hunt"), which he probably felt was beneath his stature after delivering three successful movies in a row for 20th Century Fox. Don't forget that he was the kind of guy who would happily bankrupt a studio back in Germany (and that the studio would practically let him), so right when he was finally regaining some respectability in the States he obviously thought things would go a bit back to normal, or at least that studio head Daryl Zanuck would show him a bit more professional courtesy than saddling him with a script with all of a day to fine-tune it.

Because Lang never seemed to figure out exactly how the Hollywood studio system worked...