Editing September 17 (section)

===1601–1900===
*[[1620]] &ndash; [[Polish–Ottoman War (1620–21)|Polish–Ottoman War]]: The Ottoman Empire defeats the Polish–Lithuanian Commonwealth during the [[Battle of Cecora (1620)|Battle of Cecora]].
*[[1631]] &ndash; Sweden wins a major victory at the [[Battle of Breitenfeld (1631)|Battle of Breitenfeld]] against the Holy Roman Empire during the [[Thirty Years' War]]. 
*[[1658]] &ndash; The [[Battle of Vilanova]] is fought between Portugal and Spain during the [[Portuguese Restoration War]].
*[[1683]] &ndash; [[Antonie van Leeuwenhoek]] writes a letter to the Royal Society describing "[[animalcule]]s", later known as [[protozoa]].<ref>{{cite web|last=Anderson |first=Douglas|title=Wrote Letter 39 of 1683-09-17 (AB 76) to Francis Aston|url=http://lensonleeuwenhoek.net/content/wrote-letter-39-1683-09-17-ab-76-francis-aston|work=Lens on Leeuwenhoek|access-date=2016-09-26|archiveurl=https://web.archive.org/web/20160820153516/http://lensonleeuwenhoek.net/content/wrote-letter-39-1683-09-17-ab-76-francis-aston|archivedate=2016-08-20}}</ref>
*[[1775]] &ndash; [[American Revolutionary War]]: The [[Invasion of Quebec (1775)|invasion of Quebec]] by the [[Continental Army]] begins with the [[Siege of Fort St. Jean]].<ref>{{cite book |last=Bird |first=Harrison |title=Attack on Quebec, the American Invasion of Canada, 1775 |url=https://archive.org/details/attackonquebecam0000bird |url-access=registration |publisher=Oxford University Press |year=1968 |ref=Bird |oclc=440055|page=93}}</ref>
*[[1776]] &ndash; The [[Presidio of San Francisco]] is founded in New Spain.
*[[1778]] &ndash; The [[Treaty of Fort Pitt]] is signed. It is the first formal treaty between the United States and a Native American tribe.
*[[1787]] &ndash; The [[Constitution of the United States|United States Constitution]] is [[Signing of the United States Constitution|signed]] at [[Independence Hall]] in [[Philadelphia]], bringing the [[Constitutional Convention (United States)|Constitutional Convention]] to an end.<ref>{{cite web|title=On this day, the Constitution was signed in Philadelphia|url=https://constitutioncenter.org/blog/today-the-constitution-was-signed-in-philadelphia|author=Bomboy, Scott|website=ConstitutionCenter.org|publisher=National Constitution Center|date=September 17, 2023|access-date=June 3, 2024}}</ref>
*[[1793]] &ndash; [[War of the Pyrenees]]: France defeats a Spanish force at the [[Battle of Peyrestortes]].
*[[1794]] &ndash; [[Low Countries theatre of the War of the First Coalition|Flanders Campaign]]: France completes its conquest of the Austrian Netherlands at the [[Battle of Sprimont]].
*[[1809]] &ndash; Peace between Sweden and Russia in the [[Finnish War]]; the territory that will become Finland is ceded to Russia by the [[Treaty of Fredrikshamn]].
*[[1849]] &ndash; American abolitionist [[Harriet Tubman]] escapes from slavery.
*[[1859]] &ndash; [[Joshua A. Norton]] declares himself "Norton I, Emperor of the United States."
*[[1861]] &ndash; [[Argentine Civil Wars]]: The State of Buenos Aires defeats the Argentine Confederation at the [[Battle of Pavón]].
*[[1862]] &ndash; [[American Civil War]]: [[George B. McClellan]]'s [[Army of the Potomac]] halts the first [[Maryland campaign|invasion]] of the [[Northern United States#American Civil War|North]] by [[Robert E. Lee]] and his [[Army of Northern Virginia]] in the single-day [[Battle of Antietam]], the bloodiest day in American military history.<ref>{{cite web|url=http://npshistory.com/brochures/anti/battle-history.pdf|title=The Battle of Antietam|website=NPSHistory.com|publisher=National Park Service|format=PDF|access-date=June 3, 2024}}</ref>
*  1862   &ndash; American Civil War: The [[Allegheny Arsenal]] explosion in [[Lawrenceville (Pittsburgh)|Lawrenceville, Pennsylvania]] results in the single largest civilian disaster during the war.<ref>{{cite web|url=https://www.battlefields.org/learn/articles/tragedy-allegheny-arsenal-horrid-moment-most-wicked-rebellion|title=The Tragedy at Allegheny Arsenal – 'A Horrid Moment of a Most Wicked Rebellion'|author=Condon, Rich|website=Battlefields.org|publisher=American Battlefield Trust|date=September 14, 2021|access-date=June 3, 2024}}</ref>
*[[1894]] &ndash; [[Battle of the Yalu River (1894)|Battle of the Yalu River]], the largest naval engagement of the [[First Sino-Japanese War]]. 
*[[1900]] &ndash; [[Philippine–American War]]: Filipinos under Juan Cailles defeat Americans under Colonel Benjamin F. Cheatham Jr. at [[Battle of Mabitac|Mabitac]].