July–September July 11 – Aaron Burr, Vice President of the United States, shoots former U.S. Secretary of the Treasury Alexander Hamilton during a duel; Hamilton dies the next day. July 27 – The Twelfth Amendment to the U.S. Constitution, which reforms the way that candidates for President and Vice President are chosen, is ratified by Tennessee, removing doubt surrounding adoption. August 11 – In reaction to Napoleon being proclaimed emperor of France, Francis II assumes the title of a hereditary emperor of Austria (as Francis I) in addition to his title as emperor of the Holy Roman Empire. This latter title will become obsolete two years later when the formation of the Confederation of the Rhine instigated by Napoleon signals the end of the Holy Roman Empire. August 20 – Lewis and Clark Expedition: The Corps of Discovery, whose purpose is to explore the Louisiana Purchase, suffers its only death when Sergeant Charles Floyd dies, apparently from acute appendicitis. September 1 – German astronomer K. L. Harding discovers the asteroid Juno.
July–September July 11 – Aaron Burr, Vice President of the United States, shoots former U.S. Secretary of the Treasury Alexander Hamilton during a duel; Hamilton dies the next day. July 27 – The Twelfth Amendment to the U.S. Constitution, which reforms the way that candidates for President and Vice President are chosen is ratified by Tennessee, removing doubt surrounding adoption. August 11 – In reaction to Napoleon being proclaimed emperor of France, Francis II assumes the title of a hereditary emperor of Austria (as Francis I) in addition to his title as emperor of the Holy Roman Empire. This latter title will become obsolete two years later when the formation of the Confederation of the Rhine instigated by Napoleon signals the end of the Holy Roman Empire. August 20 – Lewis and Clark Expedition: The Corps of Discovery, whose purpose is to explore the Louisiana Purchase, suffers its only death when Sergeant Charles Floyd dies, apparently from acute appendicitis. September 1 – German astronomer K. L. Harding discovers the asteroid Juno.