I know some think that was Custer's plan - if he could get into a position to separate the women and children from the warriors, he would then be able to intimidate the warriors into returning to the reservation. Maybe that was the point of Reno's attack - The warriors would focus on attacking Reno while the women and children would flee in the opposite direction. It would have been nice if Custer had bothered to inform Reno and some of his other officers who survived what "the plan" was.
Yeah, well, Custer never was one for sharing a plan with his subordinates, probably because he often flew by the seat of his pants, so to speak. The man was brave, and had some moments of innovation, but he was really not all that good a commander.