He led the North in the American Civil War against the South, who wanted to break away from the United States.
He also came up with the Emancipation Proclamation, which gave all slaves in the US their freedom.
He was assassinated in 1865 by John Wilkes Booth, who was a supporter of the South.
Franklin D. Roosevelt
He ruled the US in the difficult years following the Great Depression, which put millions of people out of work, and during World War Two.
His "New Deal" saw lots of building projects to give people work, and he helped come up with the United Nations to try to prevent any more big wars.