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The 1840s

1,722 sourced entries across 10 years, inside the 19th century. Each year below opens its own page; the lines under it are that year’s highest-ranked entries.

1840 CE174 entries

  • January 22 – British colonists reach New Zealand, officially founding the settlement of Wellington.
  • 5 February — Māori chiefs assemble at Waitangi to discuss the terms of the Treaty of Waitangi.
  • April 2 – The Washingtonian movement for teetotalism is founded by a group of alcoholics in Baltimore, Maryland.

1841 CE156 entries

  • 20 January — publication of the terms of the Convention of Chuenpi, signed between British Plenipotentiary Charles Elliot and Chinese Imperial Commissioner Qishan during the First Opium War between the United Kingdom and the Qing dynasty of China
  • 1 November – Daniel O'Connell is elected as the first Roman Catholic Lord Mayor of Dublin in centuries.
  • December 20 – The first multilateral treaty for the suppression of the African slave trade, the Treaty for the Suppression of the African Slave Trade, signed in London by the representatives of Austria, Britain, France, Prussia and Russia.

1842 CE159 entries

  • March 5 – Mexican troops led by Rafael Vasquez invade Texas, briefly occupy San Antonio, and then head back to the Rio Grande. This is the first such invasion since the Texas Revolution.
  • August 29 – The Treaty of Nanking, an unequal treaty between the United Kingdom and Qing dynasty China, ends the First Opium War, and establishes Hong Kong as a British colony (later a British dependent territory until 1997).
  • November 26 – The University of Notre Dame in South Bend, Indiana is established by Father Edward Sorin of the Roman Catholic Congregation of Holy Cross.

1843 CE169 entries

  • February 6 – The Virginia Minstrels perform the first minstrel show (Bowery Amphitheatre, New York City).
  • September – Ada Lovelace translates and expands Menabrea's notes on Charles Babbage's Analytical Engine, including an algorithm for calculating a sequence of Bernoulli numbers, regarded as the world's first computer program.
  • December – Gwalior campaign was fought between the United Kingdom and Marathan forces in Gwalior in India

1844 CE156 entries

  • June 12 –In the United States, after nine days of heavy rains, the Missouri River and the Mississippi River overflow their banks as the Great Flood of 1844 begins. The water begins to recede by June 28 and the rivers return to their normal level by mid-July.
  • August 16 – Narciso Claveria, Governor-General of the Philippines, makes a decree announcing that Monday, December 30, 1844, will be immediately followed by Wednesday, January 1, 1845. (Tuesday, December 31, 1844, is removed from the Philippine calendar because since 1521 the country has been one day behind its Asian neighbors.)
  • December 31 – This date is omitted from the calendar in the Philippines in order to align it with the calendar elsewhere in East Asia, essentially moving the International Date Line to the east of the archipelago.

1845 CE171 entries

  • March 3 – Florida is admitted as the 27th U.S. state (see History of Florida).
  • 9 September – A potato blight breaks out in Ireland, beginning the Great Famine.
  • 30 December – Queen's Colleges of Belfast, Cork and Galway are incorporated in Ireland.

1846 CE165 entries

  • May 15 – Under the leadership of Prime Minister Robert Peel, the House of Commons of the United Kingdom votes to repeal the Corn Laws by passing an Importation Bill, replacing the old colonial mercantile trade system with free trade in response to the Great Famine (Ireland). On June 25 the Duke of Wellington persuades the House of Lords to pass the Act, which will take full effect from February 1849. Peel, however, is forced to resign.
  • September 7 – The portion of the District of Columbia in the United States that was ceded by Virginia in 1790 is re-ceded to Virginia.
  • 22 September – the Great Western Steamship Company's SS Great Britain, bound from Liverpool for New York, runs aground in Dundrum Bay (County Down). She lies here for almost a year, protected by temporary measures organised by her designer, I. K. Brunel.

1847 CE175 entries

  • June – E. H. Booth & Co. Ltd, which becomes the northern England supermarket chain Booths, is founded when tea dealer Edwin Henry Booth, 19, opens a shop called "The China House" in Blackpool.
  • June – E. H. Booth & Co. Ltd, which becomes the Northern England supermarket chain Booths, is founded when 19-year-old tea dealer Edwin Henry Booth opens a shop called "The China House" in Blackpool.
  • 28 December - Augustus Short, the first Anglican bishop of Adelaide, South Australia arrives from England.

1848 CE216 entries

  • March 15 – Hungarian Revolution of 1848: The Hungarian young revolutionary intellectuals, led by Sándor Petőfi, Mór Jókai and others, called the Márciusi Ifjak (Young men of March) organize peaceful mass demonstrations in Pest, forcing the city's Habsburg authorities to accept the 12 Points: the Hungarian claim for freedom and self-determination within the Habsburg Empire. On the same day, Lajos Kossuth and representatives of the Diet of Hungary go to Vienna, and force the emperor and Hungarian king Ferdinand I of Austria to accept Hungarian claims for self-determination within the empire.
  • June – The Serbians from Vojvodina start a rebellion against the Hungarian government.
  • November 1 – In Boston, Massachusetts, the first medical school for women, the Boston Female Medical School (which later merges with Boston University School of Medicine), opens.

1849 CE181 entries

  • January 8 – Hungarian Revolution of 1848: Romanian armed groups massacre 600 unarmed Hungarian civilians, at Nagyenyed.
  • April 26 – Hungarian Revolution of 1848 – Battle of Komárom: Hungarian forces relieve the city and castle with the same name from a long Austrian siege. The Austrian imperial forces and their Croatian, Romanian and Serbian allies are chased out from Hungary, or near the borders of the country.
  • May 3 – The Mississippi River levee at Sauvé's Crevasse breaks, flooding much of New Orleans, Louisiana.