Year 1817 (MDCCCXVII) was a common year starting on Wednesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 12-day slower Julian calendar).

Events of 1817

January–March

• January 19 – An army of 5,423 soldiers, led by General José de San Martín, starts crossing the Andes from Argentina to liberate Chile and then Peru.

• February 12 – Battle of Chacabuco: The Argentine/Chilean patriotic army defeats the Spanish.

• March 3

• *President James Madison vetoes John C. Calhoun's Bonus Bill.

• *U.S. Congress passes law to split the Mississippi Territory, after Mississippi drafts a constitution, creating the Alabama Territory effective in August.

• March 4 – James Monroe succeeds James Madison as President of the United States of America.

April–June

• April – An earthquake strikes Palermo, Italy.

• April 3 – Princess Caraboo appears in Almondsbury in Gloucestershire, England.

• April 15 – The first American school for the deaf opens in Hartford, Connecticut.

• April 17 – Martin Van Buren passes the Erie Canal bill.

• April 29 – The Rush-Bagot Treaty is signed.

• May – The General Convention of the Episcopal Church founds the General Theological Seminary while meeting in New York City.

• June 25 – A large riot breaks out in Copenhagen Prison; the army is sent to quell it.

July–September

• July 4 – At Rome, New York, construction on the Erie Canal begins.

• August 15 – By act of the U.S. Congress (March 3), the Alabama Territory is created by splitting the Mississippi Territory in half, on the day the Mississippi constitution is drafted, 4 months before Mississippi becomes a U.S. state.

• August 22 – The city of Araraquara, Brazil is founded.

• August 23 – An earthquake near the site of the ancient Greek city of Helike results in 65 deaths.

October–December

• October 31 – Emperor Ninkō accedes to the throne of Japan.

• November 20 – The first Seminole War begins in Florida.

• November 22 – Frédéric Cailliaud discovers the old Roman emerald mines at Sikait, Egypt.

• December 10 – Mississippi is admitted as the 20th U.S. state, formerly the Mississippi Territory.

"An 1820 Claim to Congress: Alabama Territory : 1817",
The Intruders, TNGenNet Inc., 2001, quick webpage:
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Undated

• Elgin Marbles are displayed in the British Museum.

• John Kidd extracts naphthalene from coal tar.

• Samuel Taylor Coleridge publishes Biographia Literaria.

• A typhus epidemic occurs in Edinburgh and Glasgow.

• The Pernambucan Revolt breaks out in Brazil.

Births

January–June

• January 6 – J. J. McCarthy, Irish architect (d. 1882)

• January 8 – Sir Theophilus Shepstone, British-born South African statesman (d. 1893)

• February 19 – King William III of the Netherlands (d. 1890)

• February 22 – Carl Wilhelm Borchardt, German mathematician (d. 1880)

• March 6 – Clémentine of Orléans, daughter of King Louis-Philippe of France and mother of Tsar Ferdinand I of Bulgaria (d. 1907)

• March 22 – Braxton Bragg, American Confederate general (d. 1876)

• April 15 – Benjamin Jowett, Master of Balliol College (d. 1893)

• May 15 – Debendranath Tagore, Indian philosopher (d. 1905)

• May 19 – Theodor August Heintzman, Canadian piano manufacturer (d. 1899)

• June 30 – Joseph Dalton Hooker, English botanist (d. 1911)

July–December

• July 12 – Henry David Thoreau, American philosopher (d. 1862)

• July 24 – Adolphe, Grand Duke of Luxembourg (d. 1905)

• July 29 – Ivan Aivazovsky, Armenian-Russian painter (d. 1900)

• August 3 – Archduke Albert, Austrian general (d. 1895)

• August 14 – Alexander H. Bailey, American politician (d. 1874)

• August 24 – Aleksey Konstantinovich Tolstoy, Russian writer (d. 1875)

• October 17 – Sir Syed Ahmad Khan (Bahadaur) Founder of the Two Nation Theory for a future Pakistan (d. 1898)

• November 3 – Leonard Jerome, American entrepreneur and grandfather of Sir Winston Churchill (d. 1891)

• November 12 – Bahá'u'lláh, Persian founder of the Bahá'í Faith (d. 1892)

• November 17 – Benjamin Champney, American painter (d. 1907)

• November 30 – Theodor Mommsen, German writer, Nobel Prize laureate (d. 1903)

Deaths

January–June

• January 12 – Juan Andres, Spanish Jesuit (b. 1740)

• January 16 – Alexander J. Dallas, American statesman and financier (b. 1759)

• March 8 – Anna Maria Lenngren, Swedish writer (b.1754)

• April 4 – André Masséna, French marshal (b. 1758)

• April 12 – Charles Messier, French astronomer (b. 1730)

• June 24 – Thomas McKean, American lawyer and signer of the Declaration of Independence (b. 1734)

July–December

• July 14 – Anne Louise Germaine de Staël, French writer (b. 1766)

• July 18 – Jane Austen, English novelist (b. 1775)

• July 19 – John Palmer, Bath architect (b. c. 1738)

• July 24 – Karađorđe Petrović, Serb leader of the First Serbian Uprising against the Ottoman Empire, and the founder of the Serbian House of Karađorđević (b. 1768)

• October 13 – Julius Caesar Ibbetson, artist (b. 1759)

• October 16 – Manuel Piar, Venezuelan military leader (b. 1774)

• November 11 – Francisco Javier Mina, Spanish military leader (b. 1789) (executed)

• November 14 – Policarpa Salavarrieta, Colombian spy and revolutionary who worked for the Independence of Colombia (b. 1795)

• November 30 – Jean-Baptiste-Melchior Hertel de Rouville, Canadian politician (b. 1748)

• 12 December – Emperor Tekle Giyorgis I of Ethiopia, (b. c. 1751)

• date unknown – Usman dan Fodio, founder of Sokoto caliphate, (b. 1754)