Thomas "Tad" Lincoln was the fourth and youngest son of the 16th President of the United States Abraham Lincoln and his wife Mary Todd Lincoln.

Abraham Lincoln was an American lawyer, politician, and statesman, who served as the 16th president of the United States, from 1861 until his assassination in 1865. Lincoln led the United States through the American Civil War, defending the nation as a constitutional union, defeating the insurgent Confederacy, playing a major role in the abolition of slavery, expanding the power of the federal government, and modernizing the U.S. economy.