Abraham Lincoln served as President of the United States during the Civil War in the 1860s, leading the Union's troops against the Confederate states and working to defeat the Confederacy. John Wilkes Booth assassinated Lincoln in April 1865 by shooting him in the back of the head during a conference intended to negotiate peace with the South. The gun used, which fired exploding bullets that could kill instantly, was the murder weapon. Lincoln was survived by his wife Mary Todd Lincoln and their four sons. Vice President Andrew Johnson succeeded Lincoln as President after his assassination.