A legendary political figure who played a key role in the American Civil War was Abraham Lincoln. As the 16th President of the United States, he led the nation through its most tumultuous period, preserving the Union and advocating for the abolition of slavery. Lincoln's Emancipation Proclamation in 1863 was pivotal in redefining the war's purpose, framing it as a struggle for freedom, which fundamentally reshaped American society and values.