text: Robert Todd Lincoln ( August 1 , 1843 -- July 26 , 1926 ) was an American lawyer and Secretary of War , and the first son of President Abraham Lincoln and Mary Todd Lincoln .
simplified: Robert Todd Lincoln ( August 1 , 1843 -- July 26 , 1926 ) was an American lawyer and Secretary of War . He was the first son of President Abraham Lincoln and his wife , Mary Todd Lincoln .