The first incumbent U.S. president to die was William Henry Harrison, on April 4, 1841, only one month after Inauguration Day. He died from complications of what at the time was believed to be pneumonia. The second American president to die in office, Zachary Taylor, died on July 9, 1850, from acute gastroenteritis. Abraham Lincoln was the first U.S. president to be assassinated. He was shot by John Wilkes Booth on the night of April 14, 1865, and died the following morning. Sixteen years later, on July 2, 1881, James A. Garfield was shot by Charles J. Guiteau, surviving for over two months before dying on September 19, 1881.