A retired US Secret Service agent named Gerald Blaine said that on the evening after the assassination of President John F. Kennedy, he almost accidentally shot President Lyndon Johnson:
Blaine heard footsteps approaching. He picked up his submachine gun and, in the darkness, pointed it at the chest of a man who turned out to be Johnson.
Blaine writes that the enormity of what had almost happened left him chilled. He realized that, 14 hours after losing one president, the nation had almost lost another one by his hand.
Link via Joe Carter | Photo: Cecil Stoughton/US National Archives