Abraham Lincoln rose from humble origins to become a great leader during the American Civil War. He led the North to preserve the Union and began the process of emancipating slaves through the Emancipation Proclamation. Lincoln's key contributions included freeing slaves in Confederate states, turning the war's focus to human freedom, and helping abolish slavery nationwide through the 13th Amendment. He set an example of honesty, leadership, and character as president before being assassinated by John Wilkes Booth in April 1865.