As to the enemy's organization and numbers, the only information I ever found trustworthy is that got by contact with him. No day should pass without having some prisoners got by "feeling the lines." These, to secure treatment as regular prisoners of war, must always tell the company and regiment to which they belong. Rightly questioned, they rarely stop there, and it is not difficult to get the brigade, division, etc. The reaction from the dangers with which the imagination had invested capture, to the commonly good-humored hospitality of the captors, makes men garrulous of whom one would not expect it. General Pope's chief quartermaster, of the rank of colonel, was captured by Stuart's cavalry in this very campaign; and since the war I have read with amazement General Lee's letters to President Davis, to the Secretary of War at Richmond, and to General Loring in West Virginia, dated August 23d, in which he says: [Footnote: Official Records, vol. xii. pt. ii. pp. 940-941.] "General Stuart reports that General Pope's chief quartermaster, who was captured last night, positively asserts that Cox's troops are being withdrawn by the way of Wheeling." Of course Lee suggests the importance of "pushing things" in the Kanawha valley. Stuart thus knew my movement on the day I left Parkersburg. Even when the captured person tells nothing he is bound to conceal, enough is necessarily known to enable a diligent provost-marshal to construct a reasonably complete roster of the enemy in a short time. In the Atlanta campaign I always carried a memorandum book in which I noted and corrected all the information of this sort which came to me, and by comparing this with others and with the lists at General Sherman's headquarters, there was no difficulty in keeping well up in the enemy's organization. It may therefore be said that every commanding officer ought to know the divisions and brigades of his enemy. The strength of a brigade is fairly estimated from the average of our own, for in people of similar race and education, the models of organization are essentially the same, and subject to the same causes of diminution during a campaign. Such considerations as these leave no escape from the conclusion that McClellan's estimates of Lee's army were absolutely destructive of all chances of success, and made it impossible for the President or for General Halleck to deal with the military problem before them. That he had continued this erroneous counting for more than a year, and through an active campaign in the field, destroyed every hope of correcting it. The reports of the peninsular campaign reveal, at times, the difficulty there was in keeping up the illusion. The known divisions in the Confederate army would not account for the numbers attributed to them, and so these divisions occasionally figure in our reports as "grand divisions." [Footnote: In his dispatch to Halleck on the morning after South Mountain (September 15), D. H. Hill's division