Currently Abraham Lincoln is one of the best presidents we ever had. But that was not always true. People who didn't want a war claimed that he was the one the that started the Civil War. Why? Because Lincoln hated slavery and sent down troops to attack the South. And that was how the Civil War began. On the other hand if we did not have that war there would still be slaves to this very day.

Source: Hall of Presidents Home Page
www.npg.si.edu/col/pres/indlist.htm