Lincoln had a wonderful faculty for understanding the topography of a country, and he was quite familiar with the one in which the army was about to operate; he carried a small chart in his pocket, on which were marked all the rivers and hills about Richmond, with the city itself, and the different points where General Lee had his forces posted, the lines of defense, and, in fact, all the information that a general of an army wanted. During our rides which were always within the lines he would stop and spread out his chart on his knees and point out to me what he would do if he were the general commanding, taking good care, at the same time, never to interfere in any way with General Grant, whom, I rather think, he considered the better strategist of the two.