Try to find a copy of “The Real Lincoln” by Thomas J. Dilorenzo. The book presents “A New Look at Abraham Lincoln, His Agenda, and an Unnecessary War”.
I found the Dilorenzo book a bit polemical, though I don't recall anything he got obviously wrong.
My recommendations would be When In the Course of Human Events by Charles Adams and Lincoln the Man by Edgar Lee Masters. Read these books as I did, verifying their assertions of fact with other resources. (Mostly I recall utilizing the Encyclopedia Britannica.)
Think about that quote chiseled into the Lincoln Memorial: “With Malice Toward None, With Charity For All.” At the time Lincoln said this (Second Inaugural Address) he was ordering his generals to burn widows and orphans out of their farms; and maybe to do worse things to the Indians.
The stuff we learned in high school about "Honest Abe" isn't all there is to learn. I say this as an Honest Yankee who has never lived south of Long Island, NY.
ML/NJ