Sup, Lincoln?

McClellan Society member Harry Smeltzer notes that ...
I have to take issue with the criticism of her (Goodwin's) use of the term "What's up?" in her apparently created Lincoln dialogue.  I believe the term was in vogue at the time, and recall its use by Francis Donaldson of the 118th PA (I think) in his letters published as "Inside the Army of the Potomac".  Sometimes it's hard to believe that we did not create all the slang and cuss used today in the last 50 years.