The Works of Abraham Lincoln. V. IV- Speeches and debates, 1858-1859 . The Original Books Collection. Abraham Lincoln (February 12, 1809 – April 15, 1865) was the16th President of the United States, serving from March 1861 until his assassination in April 1865. Lincoln successfully led his country through its greatest constitutional, military and moral crisis – the American Civil War – preserving the Union while ending slavery, and promoting economic and financial modernization.