McKinley was shot twice at the Pan-American Exposition on September 6 by Leon Czolgosz, an anarchist angered by inequality and inspired by the assassination of Italy's king. Doctors could not locate one bullet, and gangrene set in around the wound. His death made Theodore Roosevelt, at 42, the youngest president in American history.
McKinley had been greeting well-wishers in a receiving line at the Temple of Music when Czolgosz, concealing a .32 revolver in a handkerchief, fired twice at close range. One bullet grazed him; the other lodged deep in his abdomen, and surgeons operating by reflected sunlight in a building without proper equipment failed to find it.
For several days the president seemed to rally, eating solid food and joking with aides, and the nation exhaled. Then gangrene spread through the wound and surrounding tissue. He died in the early hours of September 14, reportedly murmuring the words to the hymn 'Nearer, My God, to Thee.'
Czolgosz was executed by electric chair six weeks later, unrepentant, declaring he had killed the president because he was an enemy of working people. McKinley's death pushed Theodore Roosevelt—already famous for the Rough Riders and viewed warily by party bosses who'd hoped the vice presidency would sideline him—into the White House, where he would remake the presidency and American foreign policy.