August 12

Crusader forces under Godfrey of Bouillon defeat a Fatimid army at the Battle of Ascalon, concluding the First Crusade.

Concluding the First Crusade's military campaign, Crusader forces under Godfrey of Bouillon decisively defeated a large Fatimid Egyptian army that had marched to recapture recently fallen Jerusalem. The victory secured the newly established Crusader states in the Levant for the time being, though sporadic conflict with regional Muslim powers continued for decades afterward.

Georgian King David IV defeats Seljuk commander Ilghazi at the Battle of Didgori.

Georgian King David IV, known as "the Builder," led a numerically inferior Georgian army to a stunning victory over a much larger Seljuk force at Didgori, effectively expelling Seljuk power from Georgian territory. The triumph ushered in what historians consider the Georgian Golden Age, a period of significant cultural, political, and territorial expansion.

Nur ad-Din Zangi defeats Crusader armies from Tripoli and Antioch at the Battle of Harim.

Muslim military leader Nur ad-Din Zangi decisively defeated a combined Crusader force from the northern Crusader states of Tripoli and Antioch near Harim, capturing several prominent Crusader nobles. The victory significantly weakened Crusader military strength in the region and set the stage for further Muslim territorial gains in subsequent decades.

Christopher Columbus reaches the Canary Islands during the early stage of his first westward voyage.

During the early stage of his first westward voyage seeking a route to Asia, Columbus's expedition made a stop at Spain's Canary Islands to restock provisions and undertake repairs before continuing across the Atlantic. The islands subsequently served as a crucial waypoint for numerous later Spanish transatlantic voyages.

Isaac Singer receives a patent for his improved sewing machine design.

American inventor Isaac Singer received a patent for significant improvements to the sewing machine, including a practical foot-pedal treadle mechanism that freed both of the operator's hands for guiding fabric. Singer's commercially successful machines and aggressive marketing helped make sewing machines a common household and industrial tool worldwide.

British surgeon Joseph Lister performs the first antiseptic surgical procedure, transforming surgical practice.

British surgeon Joseph Lister applied his theories about germ-based infection, inspired by Louis Pasteur's research, to perform what is considered the first genuinely antiseptic surgical operation using carbolic acid to sterilize instruments and wounds. His methods dramatically reduced postoperative infection rates and transformed surgical practice worldwide.

France and Britain declare war on Austria-Hungary during the opening weeks of World War I.

As the alliance system triggered by the assassination of Archduke Franz Ferdinand continued to draw more nations into conflict, France and Britain formally declared war on Austria-Hungary, widening the young conflict that would soon become known as World War I across multiple additional fronts.

IBM introduces its Personal Computer, helping establish the modern home and office computing market.

IBM entered the rapidly growing personal computer market with its own machine, built using off-the-shelf components and an open architecture that, somewhat unexpectedly, allowed other manufacturers to produce compatible clones. This openness helped establish the IBM-compatible PC as the dominant computing standard for decades to follow.

Japan Air Lines Flight 123 crashes, killing 520 people in history's deadliest single-aircraft disaster.

A Japan Air Lines Boeing 747 suffered a catastrophic structural failure caused by an improperly repaired rear pressure bulkhead, leading to a loss of control that resulted in a crash into a mountainside. The disaster killed 520 of the 524 people aboard, remaining the deadliest single-aircraft accident in aviation history.

The Unite the Right rally in Charlottesville, Virginia, turns violent, resulting in three deaths and dozens of injuries.

A rally organized by white nationalist and far-right groups protesting the planned removal of Confederate monuments turned violent when a participant deliberately drove a car into a crowd of counter-protesters, killing one woman and injuring dozens of others. The event prompted widespread national condemnation and renewed debate over Confederate memorials.