Ulysses S. Grant served under a President of the United States.
Abraham Lincoln ( [ ˈeɪbrəhæm_ˈlIŋkən ] February 12 , 1809 -- April 15 , 1865 ) was an American politician and lawyer who served as the 16th President of the United States from March 1861 until his assassination in April 1865 . Ulysses S. Grant . As Commanding General ( 1864 -- 69 ) , Grant worked closely with President Abraham Lincoln to lead the Union Army to victory over the Confederacy in the American Civil War .