
 Charles Willson Peale's full-length portrait of George Washington on the American Revolutionary War battlefield fetched $21.3 million at auction Saturday,January 21, setting a world record for the sale of an American portrait, Christie's auction house said.   "George Washington at Princeton," signed and dated 1779 by the Revolutionary period's premier portrait artist, was one of eight full-length portraits of Washington painted by Peale between 1779 and 1781.   It was the only one known to be in private hands; other versions of the iconic portrait are at the Metropolitan Museum of Art and at museums in Philadelphia and Williamsburg, Virginia.