Sandburg was a poet more than an historian. And I think it shows in both Prairie Years and War Years. Both are interesting reads but they aren't serious history, at least that's how they struck me.
Unfortunately, history is often written selectively, with an agenda. This is particularly true of what I call “popular history.” Before I make a judgment of historical “truth,” I usually do not rely upon one source, but several. It’s like doing trial work. You hear wildly conflicting accounts, and have to sift through them to find where the truth really lies.
My favorite way to post excerpts is to get different accounts of the same event. That helps to zero in on what really happened as well as giving alternate, but factual looks at something. I have to much reading to catch up on to get another Lincoln bio, so if you or anyone else wants to post excerpts from other works it will be appreciated. Especially date-specific stuff that we can cover from different angles.