1800

1800 (MDCCC) was an exceptional common year starting on Wednesday of the Gregorian calendar and a leap year starting on Sunday of the Julian calendar, 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 1st year of the 1800s decade. As of the start of 1800, the Gregorian calendar was 11 days ahead of the Julian calendar, which remained in localized use until 1923.

Millennium:	2nd millennium
Centuries:	17th century – 18th century – 19th century
Decades:	1770s  1780s  1790s  – 1800s –  1810s  1820s  1830s
Years:	1797 1798 1799 – 1800 – 1801 1802 1803

1800 in other calendars

Gregorian calendar	1800 MDCCC
French Republican calendar	8–9
Ab urbe condita	2553
Armenian calendar	1249 ԹՎ ՌՄԽԹ
Assyrian calendar	6550
Balinese saka calendar	1721–1722
Bengali calendar	1207
Berber calendar	2750
British Regnal year	40 Geo. 3 – 41 Geo. 3
Buddhist calendar	2344
Burmese calendar	1162
Byzantine calendar	7308–7309
Chinese calendar	己未年 (Earth Goat) 4496 or 4436     — to — 庚申年 (Metal Monkey) 4497 or 4437
Coptic calendar	1516–1517
Discordian calendar	2966
Ethiopian calendar	1792–1793
Hebrew calendar	5560–5561
Hindu calendars
- Vikram Samvat	1856–1857
- Shaka Samvat	1721–1722
- Kali Yuga	4900–4901
Holocene calendar	11800
Igbo calendar	800–801
Iranian calendar	1178–1179
Islamic calendar	1214–1215
Japanese calendar	Kansei 12 (寛政１２年)
Javanese calendar	1726–1727
Julian calendar	Gregorian minus 11 or 12 days
Korean calendar	4133
Minguo calendar	112 before ROC 民前112年
Nanakshahi calendar	332
Thai solar calendar	2342–2343
Tibetan calendar	阴土羊年 (female Earth-Goat) 1926 or 1545 or 773     — to — 阳金猴年 (male Iron-Monkey) 1927 or 1546 or 774

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.