The most famous, or infamous, traitor in American history was Major General Benedict Arnold—a brilliant officer, a whirlwind hero, a trusted military comrade of George Washington's. The culmination of his treachery was a plot to deliver up West Point, America's strongest and most important fortification, to the British. AMERICAN HERITAGE presents in this issue two segments of Benedict Arnold's complex story. “How the Traitor Was Unmasked,” by James Thomas Flexner, is the exciting and moving account of General Washington's discovery of his friend's “villainous perfidy”—an excerpt from Mr. Flexner's book, George Washington in the American Revolution, to be published early in 1968 by Little, Brown and Company. In “The Aftermath of Treason,” Milton Lomask tells the story of the Arnolds' subsequent life in England and Canada. —The Editors