WI: Jefferson Davis is assassinated?

How does this affect the war? How does President Stephens do as the President? Is the South still defeated? Is the war shorter or longer? Does this cause Lincoln to be assassinated earlier?
I think just when Davis is assassinated is a very important factor here. In any case, I could easily see Stephens doing a worse job than Davis. Tyrant or not, Davis' policies were about the only thing holding the Confederacy together.