Morphy against Eugène Rousseau, New Orleans 1849 — a King's Knight's Opening in which Black's early 3. P. to K. B's 4th invites a vigorous attack. Notes by Löwenthal.
3…f5An unusual move in this opening, and one not to be recommended.
5…d6Shutting in the K's B. Black should rather have played B. to Q. B's 4th.
10.Nce4Mr. Morphy's sacrifices, as we have observed before, are almost always sound. Here, whether the proffered Kt. is taken or not, White's Pieces are rapidly developed without any risk whatever being incurred.
J. Löwenthal, Morphy's Games of Chess (1860) · Public domain · source