[Sherman, in his Official Report, after mentioning the receipt by him of Tyler's order to "cross over with the whole brigade to the assistance of Colonel Hunter"--which he did, so far as the Infantry was concerned, but left his battery under Ayres behind, on account of the impassability of the bluff on the Western bank of Bull Run --says: "Early in the day, when reconnoitering the ground, I had seen a horseman descend from a bluff in our front, cross the stream, and show himself in the open field, and, inferring we could cross over at the same point, I sent forward a company as skirmishers, and followed with the whole brigade, the New York Sixty-ninth leading." This is evidently the ford at the elbow of Bull Run, to the right of Sherman's front, which is laid down on the Army-maps as "Poplar Ford," and which McDowell's engineers had previously discovered and mapped; and to which Major Barnard of the U. S. Engineer Corps alludes when, in his Official Report, he says: "Midway between the Stone Bridge and Sudley Spring our maps indicated another ford, which was said to be good." The Comte de Paris, at page 241, vol. I. of his admirable "History of the Civil War in America," and perhaps other Military historians, having assumed and stated--upon the strength of this passage in Sherman's Report--that "the Military instinct" of that successful soldier had "discovered" this ford; and the impression being thus conveyed, however undesignedly, to their readers, that McDowell's Engineer corps, after spending two or three days in reconnaissances, had failed to find the ford which Sherman had in a few minutes "discovered" by "Military instinct;" it is surely due to the truth of Military history, that the Engineers be fairly credited with the discovery and mapping of that ford, the existence of which should also have been known to McDowell's brigade commanders.