Found it!
The Civil War: A Narrative, volume 2 published in 1963.
From the Bibliographical Note at the end of the book, page 971.
“In a quite different way, I am obligated also to the governors of my native state and the adjoining states of Arkansas and Alabama for helping to lessen my sectional bias by reproducing, in their actions during several of the years that went into the writing of this volume, much that was least admirable in the position my forebears occupied when they stood up to Lincoln. I suppose, or in any case fervently hope, it is true that history never repeats itself, but I know from watching these three gentlemen that it can be terrifying in its approximations, even when the reproduction - deriving, as it does, its scale from the performers - is in miniature.”
You’ll have to decide for yourself whether this view violates Foote’s principle of not judging the men of one era from the standpoint of another era.
Interesting - good find. Several points:
1. Your original point was to counter my point that Foote tilted South. This statement, if read literally, would say that while he still tilted South, current events made him less so - as opposed to being pro Northern i..e tilting the other way.
2. He’s rewording the old saw “History doesn’t repeat but it does rhyme”.
3. Does this statement contradict his own self-stated principles? I think that is a hard one to answer. Again, if read completely literally current events are affecting his affections shall we say, not his absolute judgments. Maybe in the same way you can root for the Red Sox but objectively think the Yankees a sounder baseball team. But it is a slippery slope, I grant you, between whether you “like” an historical figure and whether you can fairly judge or make sense of their actions.
4. On a personal note, I find the statement rather pompous. “I am obligated ....” “ .....these three gentleman ....”.
It’s as if he’s assuming the gentility of the 19th century, your most obedient servant, yada, yada, yada. Yet, it’s a bit out of place in the 20th century.