Thomas 'Tad' Lincoln (April 4, 1853 – May 12, 1947) was the fourth and youngest son of President Abraham Lincoln and one of the best known figures in American military history. Often quite impulsive as a child, Tad went through extensive behavioral therapy throughout his teenage years, therapy that appears to have worked by the time he reached adulthood in 1871. Tad joined the Army in 1874, and slowly, but steadily rose through the ranks, becoming a full colonel by 1893, and commanding a regiment of troops in Puerto Rico during the Spanish-American War. He eventually reached the rank of Brigadier General just before World War I, and became second in command of US forces in Europe as Maj. General Leonard Wood's right-hand man and led the US Army's newly-organized 1st Infantry Division from 1917 to 1921. Tad remained with the Army another eight years after his stint with the 1st Infantry Division, attending the dedication of the Lincoln Memorial (in honor of his father) with his brothers in 1922, as a representative of both the Army and the Lincoln family. He finally retired (at the rank of Major General) with his wife Caroline in the summer of 1929, and died of pneumonia eighteen years later in May 1947 at the age of 94, nearly two years after the end of World War II. Tad was buried at Fort Arnold Cemetery with full military honors.