1691 (MDCXCI) was a common year starting on Monday (dominical letter G) of the Gregorian calendar and a common year starting on Thursday (dominical letter D) of the Julian calendar, the 1691st year of the Common Era (CE) and Anno Domini (AD) designations, the 691st year of the 2nd millennium, the 91st year of the 17th century, and the 2nd year of the 1690s decade. As of the start of 1691, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.
March 5 – Nine Years' War: French troops under Marshal Louis-Francois de Boufflers besiege the Spanish-held town of Mons.
March 20 – Leisler's Rebellion: A new governor arrives in New York – Jacob Leisler surrenders after a standoff of several hours.
March 29 – The Siege of Mons ends in the city’s surrender.
April 9 – A fire at the Palace of Whitehall in London destroys its Stone Gallery.
May 6 – The Spanish inquisition condemns and forcibly baptizes 219 xuetas in Palma, Majorca. When 37 try to escape the island, they are burned alive at the stake.
May 16 – Jacob Leisler is hanged for treason.
June 23 – Ahmed II (1691–1695) succeeds Suleiman II (1687–1691) as emperor of the Ottoman Empire.
July 12
Pope Innocent XII becomes the 242nd pope, succeeding Pope Alexander VIII.
Williamite War in Ireland: Battle of Aughrim: Protestant Williamite forces led by Godert de Ginkell decisively defeat Jacobites under the Marquis de St Ruth (who is killed).
September 18 – Battle of Leuze: English and Dutch forces defeated by the French in the War of the Grand Alliance.
October 3 – The Treaty of Limerick, ending the Williamite War in Ireland and guaranteeing civil rights to Roman Catholics, is signed. (It was broken "before the ink was dry") The Flight of the Wild Geese — the departure of the Jacobite army — follows.
Michel Rolle invents Rolle's theorem, an essential theorem of mathematics.
In New England the two separate colonies of Massachusetts Bay Colony and Plymouth Colony are united into a single entity by an act of the King and Queen of England.
The Khalkha submit to the Manchu invaders, bringing most of modern-day Mongolia under the rule of the Qing dynasty.
Textile factory Barnängens manufaktur is founded in Stockholm, Sweden.
February 27 – Edward Cave, English editor and publisher (d. 1754)
April 5 – Louis VIII, Landgrave of Hesse-Darmstadt (d. 1768)
April 9 – Johann Matthias Gesner, German classical scholar (d. 1761)
June 17 – Giovanni Paolo Pannini, Italian painter and architect (d. 1765)
August 25 – Alessandro Galilei, architect and mathematician (d. 1736)
September 29 – Richard Challoner, English Catholic prelate (d. 1781)
October 1 – Arthur Onslow, English politician (d 1768)
October 28 – Peder Tordenskjold, Norwegian naval hero (d. 1720)
January 13 – George Fox, English founder of the Society of Friends (b. 1624)
January 17 – Richard Lower, English physician (b. 1631)
February 1 – Pope Alexander VIII (b. 1610)
April 3 – Jean Petitot, Swiss enamel painter (b. 1607)
May 11 – Colonel John Birch, English soldier (b. 1615)
May 16 – Jacob Leisler, German-born American colonist (b. 1640)
May 23 – Adrien Auzout, French astronomer (b. 1622)
May 29 – Cornelis Tromp, Dutch admiral (b. 1629)
June 23 – Suleiman II, Sultan, Ottoman Empire (b. 1642)
July 12 – Marquis de St Ruth (killed at the Battle of Aughrim)
July 16 – François-Michel le Tellier, Marquis de Louvois, French war minister (b. 1641)
July 30 – Daniel Georg Morhof, German writer and scholar (b. 1639)
August 14 – Richard Talbot, 1st Earl of Tyrconnel, Irish rebel (b. 1630)
September 12 – John George III, Elector of Saxony (b. 1647)
October 9 – William Sacheverell, English statesman (b. 1638)
October 10 – Isaac de Benserade, French poet (b. 1613)
November 14 – Tosa Mitsuoki, Japanese painter (b. 1617)
November 15 – Aelbert Cuyp, Dutch painter (b. 1620)
December 8 – Richard Baxter, English clergyman (b. 1615)
December 31 – Robert Boyle, English chemist who formulated Boyle's Law, which states that under conditions of constant temperature, the pressure and volume of a gas are inversely proportional (b. 1627)
date unknown – Bárbara Coronel, Spanish stage actress (b. 1632)
Mariyam Kaba'afa'anu Rani Kilege, queen mother and regent of the Maldives
probable – Elizabeth Polwheele, English playwright (b. c. 1651)
This is one of the numbers, in certain fonts, that can be read upside down, and displays the same number.
