Omg I need this so bad XD and having Slenderman as a known legend during that time is not as far fetched as you might think, considering the hessian mercenaries that came from Germany and Poland around that time, they would probably use said mythological creature as a scare tactic. (In Germany in the 1600's there were apparent sightings of a Slenderman like figure and the tales of him were used to keep children in line :P)