Illustration shows portrait of Abraham Lincoln. Abraham Lincoln (February 12, 1809 - April 15, 1865) was the 16th President of the United States. He successfully led the country through its greatest internal crisis, the American Civil War, preserving the Union and ending slavery. As the war was drawing to a close, Lincoln became the first American president to be assassinated. Before his election in 1860 as the first Republican president, Lincoln had been a lawyer, an Illinois state legislator, a member of the United States House of Representatives, and twice an unsuccessful candidate for election to the Senate.