A gold medal owned by George Washington and the Marquis de Lafayette, heroes of the U.S. Revolutionary War, sold today for $5.31 million at Sotheby's in New York. The medal, only 1 1/2 inches (3.8 centimeters) tall, was estimated to fetch $4 million to $10 million. New York dealer Christophe Van de Weghe bid for the medal on behalf of Fondation de Chambrun, which administers Chateau LaGrange in Courpalay, France, where Lafayette's papers are housed. The price includes commissions. "How do you value a national treasure?" Sotheby's Vice Chairman David Redden said before the sale. "There are no comparables." Washington commissioned the medal about 1783 to commemorate the founding of the Society of the Cincinnati, a group that included his close friend Lafayette and others who had fought in the Revolutionary War. The designer of the medal, Pierre Charles L'Enfant, was an architect and engineer who later created the urban plan for Washington, D.C. Hanging from a pale blue, 4-inch ribbon, the medal depicts an eagle surrounded by a laurel wreath. Latin words meaning "He left everything to serve the republic" appear in blue and gold enamel. After Washington's death in 1799, the medal descended in his family until 1824, when it was presented to Lafayette. Washington and Lafayette forged their friendship in 1777, when the aristocratic 19-year-old Frenchman sailed to America to aid Washington's battle for independence. The medal's seller was the Baronne Meunier du Houssoy, Lafayette's great-great-granddaughter. The family chose an opportune moment for the sale. Celebrations this year honoring the 250th anniversary of Lafayette's birth include an exhibition that recently opened at the New-York Historical Society. "French Founding Father: Lafayette's Return to Washington's America," runs through Aug. 10. The auction of the medal reflects the recent vogue for items associated with early American history. Last year, Sotheby's sold four Revolutionary War battle flags for $17.3 million.