James Garfield (November 19, 1831-September 19, 1881) was the 20th (1881) president of the United States, and the second U.S. President to be assassinated. He was shot by Charles J. Guiteau, on July 2 1881, just a few months after taking office. His assassin was apparently upset for being passed over as the United States consul in Paris. One of the bullets that struck Garfield lodged in his back and could not be found. He became increasingly ill over an several months because of infection and died on September 19, 1881.
He found a proof for the Pythagorean Theorem.