Abraham Lincoln was the 16th President of the United States of America.
In 1863, the Doctor gave to President Lincoln a sketched map he had made of the Confederate lines at Gettysburg. Lincoln gave the map to General Grant, thus aiding the Union Army to win the Battle of Gettysburg. (TVC: Backtime)
On 19th November of that year, Lincoln delivered his Gettysburg Address. The Doctor, Ian Chesterton, Barbara Wright and Vicki watched the speech on the Time-Space Visualiser. (DW: The Chase)
On 5th April 1865, the Doctor saved Lincoln from an assassination attempt in Richmond, Virginia. (TN: Blood and Hope)
The Doctor warned Lincoln not to go to the theatre. (BFA: Minuet in Hell)