Events of 1786

January–June

• January 3 – The Treaty of Hopewell is signed between the United States of America and the Choctaw Nation.

• January 10 – The Treaty of Hopewell is signed between the United States of America and the Chickasaw Nation.

• May 1 – Mozart's opera The Marriage of Figaro premieres in Vienna.

• May 21 – The trial of the Necklace Affair ends in Paris.

• June 10 – An earthquake-caused landslide dam on the Dadu River gives way, killing 100,000 in the Sichuan province of China.

• June 25 – Gavriil Pribylov discovers St. George Island of the Pribilof Islands in the Bering Sea.

July–December

• August – James Rumsey tests his first steam boat in the Potomac river at Shepherdstown Virginia (now West Virginia).

• August 1 – Caroline Herschel discovers a comet (the first discovered by a woman).

• August 8 – Mont Blanc is climbed for the first time by Dr. Michael-Gabriel Paccard and Jacques Balmat.

August 8: Mont Blanc climbed.

• August 11 – Captain Francis Light, known as the founder of Penang, lands in Penang and renames it Prince of Wales Island in honour of the heir to the British throne.

• August 29 – Shays' Rebellion begins in Massachusetts.

• September–December – Goethe undertakes his Italian Journey (published in 1817).

• September 2 – A hurricane strikes Barbados.

• November 7 – The oldest musical organization in the United States (the Stoughton Musical Society) is founded.

• November 30 – Peter Leopold Joseph of Habsburg-Lorraine, Grand Duke of Tuscany, promulgates a penal reform making his country the first state to abolish the death penalty. November 30 is therefore commemorated by 300 cities around the world as Cities for Life Day.

• December 4 – Mission Santa Barbara is founded by Father Fermín Francisco de Lasuén, becoming the 10th mission in the California mission chain.

December 4: Mission Santa Barbara is founded.

Undated

• Robert Burns publishes Poems, Chiefly in the Scottish Dialect.

• Francis Light acquires the island of Penang from the Sultan of Kedah on behalf of the British East India Company. It is the first British colony in South-East Asia.

• An Anglo-Spanish treaty gives Belize to Britain.

• The first ship leaves Britain for Botany Bay, Australia: 820 out of 1,138 aboard are convicts.

• The trade with Iceland is opened to all Danish and Norwegian traders.

• Reykjavík, the capital of Iceland, is founded.

• The town of Martinsborough, North Carolina, itself named for Royal Governor Josiah Martin in 1771, is renamed "Greenesville" in honor of United States General Nathanael Greene by the North Carolina General Assembly; the name "Greenesville" is later shortened to become Greenville.

Births

• January 8 – Nicholas Biddle, President of the Second Bank of the United States (d. 1844)

• January 12 – Sir Robert Inglis, Bt, English politician (d. 1855)

• January 23 – Auguste de Montferrand, French architect (d. 1858)

• February 16 – Maria Pavlovna of Russia, Grand duchess of Saxe-Weimar Eisenach (d. 1859)

• February 24 – Martin W. Bates, U.S. Senator from Delaware (d. 1869)

• February 24 – Wilhelm Grimm, German philologist and folklorist (d. 1859)

• March 22 – Joachim Lelewel, Polish historian (d. 1861)

• June 13 – Winfield Scott, American general and Presidential candidate (d. 1866)

• August 17 – David "Davy" Crockett, American frontiersman (d. 1836)

• August 25 – King Ludwig I of Bavaria (d. 1868)

• September 10 – William Mason, American politician (d. 1860)

• September 11 – Friedrich Kuhlau, German composer (d. 1832)

• September 18 – King Christian VIII of Denmark (d. 1848)

• September 24 – Charles Bianconi, Italian-Irish entrepreneur

• September 29 – Guadalupe Victoria, 1st President of Mexico (d. 1843)

• November 18

• *Henry Bishop, English composer (d. ??)

• *Carl Maria von Weber, German composer (d. 1826)

• December 12 – William L. Marcy, American statesman (d. 1857)

• Unknown dates

• *Jean-François Barrière, French historian

• *Kim Jeonghui, Korean epigrapher (d. 1856)

• *Alexander Bryan Johnson, American philosopher (d. 1867)

• probable – Moshoeshoe I of Lesotho (d. 1870)

Deaths

• January 7 – Jean-Étienne Guettard, French physician and scientist (b. 1715)

• January 14 – Meshech Weare, Governor of New Hampshire (b. 1713)

• February 28 – John Gwynn, English architect and engineer (b. 1713)

• March 11 – Charles Humphreys, American delegate to the Continental Congress (b. 1714)

• April 10 – John Byron, British naval officer (b. 1723)

• May 15 – Eva Ekeblad, Swedish scientist (b.1724)

• May 19 – John Stanley, English composer (b. 1712)

• May 21 – Carl Wilhelm Scheele, Swedish chemist (b. 1742)

• May 25 – Pedro III of Portugal, consort of Queen Maria I of Portugal (b. 1717)

• August 17 – King Frederick II of Prussia ("Frederick the Great") (b. 1712)

• September 5 – Jonas Hanway, English merchant, traveler, and philanthropist (b. 1712)

• October 2 – Augustus Keppel, 1st Viscount Keppel, British admiral (b. 1725)

• October 17 – Johann Ludwig Aberli, Swiss artist (b. 1723)

• November 30 – Bernardo de Gálvez, Spanish military leader who aided the United States in its quest for independence in the American Revolutionary War (b. 1746)

• December 26 – Gasparo Gozzi, Italian critic and dramatist (b. 1713)

• Moses Mendelssohn, Jewish philosopher (b. 1729)