“Now let me trace for a moment the sequence of events that led up to the secession crisis. Prelude to Southern Secession. I'll begin by saying that the decisive act of secession—the secession which caused all future secessions—was not what happened after Lincoln’s election. It was the secession of the seven states of the Deep South from the Democratic convention in Charleston of 1860. As far as I know, Mr. DiLorenzo doesn’t even know anything about this. He can still comment on that when he wants to.”

The Civil War: A Narrative, Volume 1: Fort Sumter to Perryville (1958)

2010s, Slavery, secession, segregation, and socialism (2010)

In China, p. 362.
1870s, Around the World with General Grant (1879)
Context: Looking back over the whole policy of reconstruction, it seems to me that the wisest thing would have been to have continued for some time the military rule. Sensible Southern men see now that there was no government so frugal, so just, and fair as what they had under our generals. That would have enabled the Southern people to pull themselves together and repair material losses. As to depriving them, even for a time, of suffrage, that was our right as a conqueror, and it was a mild penalty for the stupendous crime of treason. Military rule would have been just to all, to the negro who wanted freedom, the white man who wanted protection, the northern man who wanted Union. As state after state showed a willingness to come into the Union, not on their own terms but upon ours, I would have admitted them. This would have made universal suffrage unnecessary, and I think a mistake was made about suffrage. It was unjust to the negro to throw upon him the responsibilities of citizenship, and expect him to be on even terms with his white neighbor. It was unjust to the north. In giving the south negro suffrage, we have given the old slave-holders forty votes in the electoral college. They keep those votes, but disfranchise the negroes. That is one of the gravest mistakes in the policy of reconstruction. It looks like a political triumph for the south, but it is not. The southern people have nothing to dread more than the political triumph of the men who led them into secession. That triumph was fatal to them in 1860. It would be no less now. The trouble about military rule in the south was that our people did not like it. It was not in accordance with our institutions. I am clear now that it would have been better for the north to have postponed suffrage, reconstruction, state governments, for ten years, and held the south in a territorial condition. It was due to the north that the men who had made war upon us should be powerless in a political sense forever. It would have avoided the scandals of the state governments, saved money, and enabled the northern merchants, farmers, and laboring men to reorganize society in the south. But we made our scheme, and must do what we can with it. Suffrage once given can never be taken away, and all that remains for us now is to make good that gift by protecting those who have received it.

2000s, States' Rights and Wrongs (2008)

Source: The Cause Lost: Myths and Realities of the Confederacy (1996), p. 180

Life and Campaigns of General Robert E. Lee https://books.google.com/books?id=BDkDAAAAYAAJ&printsec=frontcover#v=onepage&q&f=false (1866) page 30. Responding to Francis Preston Blair relayed an offer to make him major-general to command the defense of Washington D.C.
1860s

Speech to the Virginia Convention (1861)

quoted by Chelsea Edwards of KABC-TV http://abc7.com/politics/calexit-supporters-hold-forum-as-effort-to-collect-signatures-continues/1753174/ (February 13, 2017)
2017

Speech to the Virginia Convention (1861)
Context: What was the reason that induced Georgia to take the step of secession? This reason may be summed up in one single proposition. It was a conviction, a deep conviction on the part of Georgia, that a separation from the North-was the only thing that could prevent the abolition of her slavery. This conviction, sir, was the main cause. It is true, sir, that the effect of this conviction was strengthened by a further conviction that such a separation would be the best remedy for the fugitive slave evil, and also the best, if not the only remedy, for the territorial evil. But, doubtless, if it had not been for the first conviction this step would never have been taken. It therefore becomes important to inquire whether this conviction was well founded.