The HISTORY Channel is set to premiere Sitting Bull, its new epic, two-night documentary event executive produced by Appian Way Productions, on Tuesday, May 27, and Wednesday, May 28, at 9 p.m. ET/PT.

MTV is no longer “Music Television,” and TLC is hardly “The Learning Channel” anymore, but of all the examples of channel drift, History Channel’s evolution seems to be the most extreme. Once devoted ...