James A. Leonard was considered to be one of the most promising chessplayers the USA ever produced. He was born on 6 November 1841 and died in late Septmeber 1862.

That's what James D. Séguin had to say about him:
<With the admitted exception of the king of chess kings, our own Paul Morphy, Pillsbury assuredly stands as the finest exponent of the game that America has yet produced – unless perhaps on a plane with him may be placed the natural (though never fairly developed) capacity of that remarkable if erratic and early eclipsed genius of the early sixties, James Leonard, of New York, whose life so soon disappeared amid the smoke and gloom of battle in the great Civil War. But, of course, lack of opportunity to attain development of genius on Leonard’s side precludes fair comparison in this instance> July 1906 American Chess Bulletin (page 127), a tribute to Pillsbury reprinted from the New Orleans Times-Democrat

And here's more on his tragic death:
<‘Moved in an evil hour – by what mocking friend we know not - he enlisted on 1 February 1862 to Company F., 88 N.Y. Volunteers, an Irish Regiment. He was in the battle of Fair Oaks, and in the seven days’ battles, till that of Savage’s Station where he was captured. Though detained less than three months, so ill would his frame bear the unavoidable hardships that he was attacked with fever and scorbutic dysentery and died at Annapolis. … The sad intelligence of his death was conveyed to the writer by his brother, who with his now doubly bereaved mother repaired to Annapolis to soothe his last moments. But before reaching him, on 26 September, his spirit departed. He remembered with blessings his friends in his last hours.’> reported by Hazeltine in the Macon Telegraph of 1867

Not sure I like this turn of phrase, because he was only ever <a young man>. How about <Despite his youth, he was...>?