1800

1800 (MDCCC) was an exceptional common year starting on Wednesday in the Gregorian calendar and a leap year starting on Sunday in the Julian calendar. It was the 1800th year of the Common Era (CE) and Anno Domini (AD) designations, the 800th year of the 2nd millennium, the 100th and last year of the 18th century, and the first year of the 1800s. As of the start of the year, the Gregorian calendar was 11 days ahead of the Julian calendar. The Julian calendar was in localized use until 1923.

On March 1 (O.S. February 18), when the Julian calendar acknowledged a leap day, and the Gregorian calendar didn't, the Julian calendar fell one day further behind, bringing the difference to 12 days until February 28 (O.S. February 16), 1900.

Events

• World population hits 1 billion.
• March 14 – Cardinal Barnaba Chiaramonti is elected pope as Pius VII.
• March 21 – Pius VII is ordained.
• April 24 – U.S. Library of Congress founded.
• May 5 – Great Britain passes the Act of Union to join Great Britain and Ireland into the United Kingdom of Great Britain and Ireland to take effect on 1 January 1801. The act is signed by King George III in August.
• May 15 – Napoleon Bonaparte crosses the Alps and invades Italy.
• June 14 – Battle of Marengo, Napoleon defeats the Austrian troops near Marengo, Italy.
• June 2 – First smallpox vaccination in North America, at Trinity, Newfoundland.
• June 27 – Pascha Jussuf Karamanli of Tripoli declares war on Sweden by having the flagpole on the consulate chopped down.
• September 5 – The island of Malta, that was occupied by the French, is conquered by British troops.
• November 1 – U.S. President John Adams becomes the first President of the United States to live in the Executive Mansion (later renamed the White House).
• November 17 – The U.S. Congress holds its first Washington, DC session.
• December 3 – Battle of Hohenlinden, the French army defeats the Austrian troops.
• December 24 – An assault on Napoleon Bonaparte fails in Paris.
• December 24 – Pierre Coudrin and Henriette Aymer de la Chevalerie found the Congregation of the Sacred Hearts of Jesus and Mary in Paris.
• Invention of the voltaic pile by Alessandro Volta: the first chemical battery
• The infrared radiation is discovered by Wilhelm Herschel.
• The Althing of Iceland, the world's oldest parliament, is abolished.

Births

for more information, see Category:1800 births.

Deaths

for more information, see Category:1800 deaths.