What is 1800?
{{Year nav|1800}} {{Year in various calendars|1800}} '''1800''' ([[Roman numerals|MDCCC]]) was an [[Century common year|exceptional common year]] [[Common year starting on Wednesday|starting on Wednesday]] in the [[Gregorian calendar]] and a [[leap year starting on Sunday]] in the [[Julian calendar]]. It was the last year of the [[18th century]]. == Events == * [[World population]] hits 1 billion. * [[March 14]] – Cardinal Barnaba Chiaramonti is elected [[pope]] as [[Pius VII]]. * [[March 21]] – [[Pope Pius VII|Pius VII]] is ordained. * [[April 24]] – U.S. [[Library of Congress]] founded. * [[May 5]] – [[Great Britain]] passes the [[Act of Union 1800|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 of the United Kingdom|George III]] in August. * [[May 15]] – [[Napoleon I of France|Napoleon Bonaparte]] crosses the Alps and invades [[Italy]]. * [[June 14]] – [[Battle of Marengo (1800)|Battle of Marengo]], Napoleon defeats the [[Austria]]n troops near [[Marengo, Italy]]. * [[June 2]] – First [[smallpox]] [[vaccination]] in [[North America]], at [[Trinity, Newfoundland]]. * [[June 27]] – Pascha [[Yusuf Karamanli|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]] – [[President (United States)|U.S. President]] [[John Adams]] becomes the first [[President (United States)|President of the United States]] to live in the Executive Mansion (later renamed the [[White House]]). * [[November 17]] – The [[Congress of the United States|U.S. Congress]] holds its first [[Washington, DC]] session. * [[December 3]] – [[Battle of Hohenlinden (1800)|Battle of Hohenlinden]], the French army defeats the Austrian troops. * [[December 24]] – An assault on [[Napoleon I of France|Napoleon Bonaparte]] fails in [[Pari