John Wilkes Booth shot Abraham Lincoln in April 1865 in order to avenge the South. How was the death of Lincoln the worst thing that could have happened to the defeated South?
Lincoln was trying to bring about a reconciliation between North and South after the Civil War. His assassination caused great grief and anger in the North and led to a general desire for harsher treatment of Southerners in the period known as Reconstruction. By eliminating Lincoln, Booth had eliminated the leader who would have offered the best possible terms and strategies for achieving a restoration of the Union. He also made Lincoln a martyr.
Lincoln was replaced by vengeful, intemperate politicians who created considerable hatred for Yankees at a time when more moderate measures would have been appropriate. The hatred aroused in the South by the Yankee occupation lasted for many decades and is still smoldering today. John Wilkes Booth wanted to be a hero, but he showed himself to be an egotist and an exhibitionist who acted rashly and caused the South nothing but harm.