Scallorns & Campbells

My g-g-grandmother Madison Scallorn received a letter in 1930 concerning the newly formed Clan Campbell Society.The letter mentions "one of your ancestors being general William Campbell, the Hero of Kings Mountain ..." and claims that "two of the best genealogists in the United States" did the research.I have my Scallorn genealogy back to John and Judith Scallorn in the late 1700s, but in all the data I've seen, I've never encountered the name Campbell in the Scallorn line.Can anyone shed some light on this matter?-Neal Whitman