A lithograph showing a chronological order of events in the life of General William Henry Harrison , including becoming a Senator and Statesman , battles at Waynes Victory , Tippecanoe and the Thames , where he battled against Native Americans . He was later elected 9th President of the United States in 1840 , and died of pneumonia in April 1841, a month after taking office . He is the only president to die in office . 1840 lithograph by George Endicott