Visible crew/equipment: At the surrender of the fort, as the English are marching out, Monroe, says "The fort is yours, Monsieur." Right as he speaks, look between the two horses' heads. In the distant valley you can see what are either two tourist busses or perhaps mobile catering vans. (01:05:40)
Answer: During inclement weather, dry sheepskins were used to keep rain from entering the barrel. During battle, wet sheepskins were used to cool down the barrel to decrease the likelihood of the powder exploding prematurely.
Greg Dwyer