It is the chief object of the following narrative to give an account of the treason of Arnold, its causes, the plans for carrying it forward, and its final issue. In executing this design, it was necessary to touch upon the events of his previous life; and, as many of these have a real interest in themselves, and others a direct bearing on the subject, it is believed no apology for introducing them will be required. The author has of course consulted all the printed books and documents, which he could find; and among others he acknowledges his obligation to M. de Mar-bois' Complot d'Arnold et de Sir Henry Clinton, published several years ago in Paris, and soon afterwards translated by Mr. Walsh for the second volume of the American Register. The parts of M. de Marbois' book, which he wrote from personal knowledge and observation, have a special value; some of the other parts would have been varied, if his materials had been more abundant and exact. Besides printed sources of information, the author has been fortunate in procuring the use of a large number of original papers in manuscript, which have not before been inspected. In the public archives of London he was allowed to peruse the entire correspondence, between the British commander in America and the ministry, concerning Arnold's defection; particularly a very ample narrative of all the transactions, dated nine days after the death of André, methodically drawn up, and signed by Sir Henry Clinton. This correspondence exhibits in a clear view the British side of the question. Among General Washington's manuscripts are also original materials, including the papers that were laid before the board of general officers to whom Andre's case was submitted, and the drafts of letters and other papers left behind by Arnold when he escaped. Arnold's letters to Congress are curious, and indicate the workings of his mind while maturing his plot. The same may be said of some of his miscellaneous letters, which have fallen into the author's hands.