I found the origin of that second Grant quote, and well as a boatload of other very interesting facts which one is quite unlikely to get from Google or AI these days, in "The Democratic Speaker's Hand-book" compiled by Matthew Carey, Jr., 1868.
https://archive.org/details/democraticspeake00caza
From page 32:
> Grant as a Talker
> He threatened to resign and cast his lot with the South.
> The editor of the Randolph Citizen recalls some interesting reminscenses of the great Reticent. He had a tongue at one time, it would seem:
> In the summer of 1861 General Grant, then Colonel of the Twenty-first Illinois Regiment of Infantry, was stationed at Mexico, on the North Missouri Railroad, and had command of the post. He remained several months, mingling freely with the people, regardless of the peculiar shade of any one's political opinions; and as the distinguished Colonel had then no thought of aspiring to the Presidency or a dictatorship, no occasion existed for the reticence to which latterly he owed the greater part of his popularity. Ulysses the Silent was then Ulysses the Garrulous, and embraced every fair opportunity which came in his way to express his sentiments and opinions in regard to political affairs. One of these declarations we distinctly remember. In a public conversion in Ringo's banking-house, a sterling Union man put this question to him: "What do you honestly think was the real object of this war on the part of the Federal Government?"
> "Sir," said Grant, "I have no doubt in the world that the sole object is the restoration of the Union. I will say further, though, that I am a Democrat--every man in my regiment is a Democrat--and whenever I shall be convinced that this war has for its object anything else than what I have mentioned, or that the Government designs using its soldiers to execute the purposes of the abolitionists, I pledge you my honor as a man and a soldier that I will not only resign my commission, but will carry my sword to the other side, and cast my lot with that people."
It's really quite remarkable that the victors of that war succeeded so marvelously in convincing people years later that it was about slavery--that the racist white people of the North went to war and died by the hundreds of thousands to free black slaves--and they have people utterly convinced of that to this day.
Lots of other enlightening stuff to be found in that book, and in other original sources. Get the facts now while you still can, and preserve them.
"This is only one among the many proofs I had witnessed of the fact, that the prejudice of color is not nearly so strong in the South as in the North. [In the South] it is not at all uncommon to see the black slaves of both sexes, shake hands with white people when they meet, and interchange friendly personal inquiries; but at the north I do not remember to have witnessed this once; and neither in Boston, New York, or Philadelphia would white persons generally like to be seen shaking hands and talking familiarly with blacks in the streets."
- James S. Buckingham, abolitionist