Sir Stuft McDuck was a member of the McDuck clan.
Richard the Lionheart needed to finance the crusades in 1189, and the then McDuck Clan leader funded him. It is logical both chronologically and because of the similarity of his appearance that that clan leader was actually Stuft McDuck. Although Stuft was dead when the crusades had started, he could have helped finance them before his death.
Sir Stuft McDuck created the first leveraged buy-out and paid 10,000 marks to buy Scotland out of feudal subjection, draining, however, the clan's coffers.
Clan McDuck was impoverished, as a result. Stuft received the title of Sir sometime during his lifetime, possibly for funding the crusades.