As he was dying in a house near Saratoga Springs, NY, U.S. Grant wrote the final pages of his memoirs.
He recalled Appomattox and the cause of the Civil War:
What General Lee‘s feelings were I do not know. As he was a man of much dignity, with an impassible face, it was impossible to say whether he felt inwardly glad that the end had finally come, or felt sad over the result, and was too manly to show it. Whatever his feelings, they were entirely concealed from my observation; but my own feelings, which had been quite jubilant on the receipt of his letter, were sad and depressed. I felt like anything rather than rejoicing at the downfall of a foe who had fought so long and valiantly, and had suffered so much for a cause, though that cause was, I believe, one of the worst for which a people ever fought, and one for which there was the least excuse. I do not question, however, the sincerity of the great mass of those who were opposed to us.
The cause of the great War of the Rebellion against the United States will have to be attributed to slavery. For some years before the war began it was a trite saying among some politicians that “A state half slave and half free cannot exist.” All must become slave or all free, or the state will go down. I took no part myself in any such view of the case at the time, but since the war is over, reviewing the whole question, I have come to the conclusion that the saying is quite true.