Sir Murdoch invented the longbow, and was made rich from selling them to the Englishmen and charging extra for the arrows. He lived in the 11 Century, and ironically died from injuries received from a longbow shot.
Behind the scenes
Sir Murdoch first appeared in Don Rosa's initial prologue to "The Life and Times of Scrooge McDuck", which also mentions the longbow story. The prologue was scrapped, but the unfinished illustrations appears in various hardcover volumes collecting Rosa's work. DuckTales is the first official appearance of the character.