The U.S. flag is derived from a red-and-white-striped symbol of unity flown by Calvinists in seven northern provinces of The Netherlands during the revolt against Spain that began in 1568.

EVERY American schoolboy knows that Betsy Ross made the first U.S. flag for George Washington and the Continental Congress in 1777. It makes a pretty story, but historians are not so sure of its accuracy. Through the years, they have searched for evidence to support a variety of theories concerning…