3 - The Grand March
The Victorian ball generally began with a Grand March where the participants lined up by couple in a long column and then walked through a series of "follow-the-leader" figures. It was a sort of mixer in that it allowed the participants to see and be seen, find out who was there that evening and see what they were wearing.
There is no step. The participants simply walk with a natural stride in time to moderate tempo march music.
The exact figures chosen were entirely at the discretion of the leader, and the Grand March seen in this video is only one of an infinite set of possibilities.
Generally, the larger the group, the simpler the patterns.