September 6

Roman Emperor Theodosius I defeats and kills the usurper Eugenius at the Battle of the Frigidus.

Roman Emperor Theodosius I led his forces to a decisive victory over the usurper Eugenius, who had seized power in the western half of the empire with the backing of pagan Roman senators seeking to restore traditional religious practices. The victory secured Theodosius's position as sole ruler and reinforced Christianity's status as the empire's dominant faith.

Christopher Columbus departs the Canary Islands, beginning the Atlantic crossing of his first voyage.

Having assembled his three ships and crew at the Canary Islands for final provisioning and repairs, Columbus departed westward into open ocean, beginning the roughly five-week Atlantic crossing that would culminate in his historic landfall in the Caribbean. This departure point became a customary stopover for subsequent Spanish transatlantic voyages for generations afterward.

The Victoria arrives back in Spain, completing the first known circumnavigation of the globe.

Commanded during its final leg by Basque navigator Juan Sebastian Elcano after Ferdinand Magellan's death in the Philippines, the Victoria limped back into the Spanish port of Sanlucar de Barrameda with just 18 surviving crew members out of the original expedition's roughly 270. The ship's arrival confirmed the completion of history's first circumnavigation of the globe.

The Spanish ship Victoria returns to port having completed the first circumnavigation of the globe, three years after setting out with Ferdinand Magellan.

Magellan himself had been killed in the Philippines partway through the voyage, and only Victoria and a handful of exhausted survivors of the original fleet of five ships and roughly 270 men made it back to Spain. Captain Juan Sebastián Elcano guided the battered vessel home laden with valuable spices. The voyage proved conclusively that the Earth could be circled by sea and vastly expanded European geographic knowledge.

The Mayflower departs Plymouth, England, carrying Pilgrims bound for North America.

Carrying 102 passengers, many of them religious separatists seeking freedom to practice their faith away from the Church of England, the Mayflower set sail after an earlier failed attempt alongside a companion ship that proved unseaworthy. The roughly two-month Atlantic crossing brought the Pilgrims to present-day Massachusetts, where they established the Plymouth Colony.

The Mayflower departs Plymouth, England, carrying the Pilgrims across the Atlantic to establish a colony in North America.

The ship's roughly 100 passengers, many fleeing religious persecution, endured a grueling ten-week voyage before sighting land far north of their intended destination in Virginia. They eventually settled at what became Plymouth Colony in present-day Massachusetts, and before disembarking drew up the Mayflower Compact, an early framework for self-governance. Their journey became a foundational story in American national mythology.

Chemist John Dalton begins using symbols to represent atoms of different elements, an early step toward modern atomic theory.

Building on the ancient Greek concept of indivisible atoms, Dalton proposed that each chemical element consisted of uniquely weighted atoms and developed a system of circular symbols to represent them in chemical diagrams, an early visual language for expressing chemical composition. His broader atomic theory, developed around the same period, laid crucial groundwork for the modern science of chemistry.

English chemist John Dalton begins using a system of symbols to represent atoms of different elements in his notebooks.

Dalton was developing the atomic theory that would become his most lasting scientific legacy, proposing that each element consisted of identical, indivisible atoms with a characteristic weight. His pictorial symbols, circles marked with dots, lines, or letters, were an early attempt to represent chemical compounds visually. Though later replaced by the letter-based notation still used today, his underlying atomic theory transformed chemistry.

President William McKinley is shot by anarchist Leon Czolgosz at the Pan-American Exposition in Buffalo, New York.

While greeting the public at the Pan-American Exposition in Buffalo, President McKinley was shot twice at close range by self-proclaimed anarchist Leon Czolgosz. McKinley initially appeared to be recovering but died eight days later from infection related to his wounds, elevating Vice President Theodore Roosevelt to the presidency and prompting increased Secret Service protection for future presidents.

The First Battle of the Marne halts the German army's advance into France, a turning point in the war's opening weeks.

After German forces had advanced to within striking distance of Paris, a determined Allied counterattack along the Marne River forced the German army into a strategic retreat, ending hopes of a swift victory envisioned under the German war plan. The battle's outcome effectively locked both sides into the prolonged trench warfare that would define most of the remaining conflict.

The British engineering firm William Foster & Co. completes the first prototype tank, nicknamed 'Little Willie', in Lincoln, England.

Developed in secrecy to break the deadlock of trench warfare on the Western Front, the tracked vehicle struggled with obstacles and was quickly superseded by an improved design better suited to crossing trenches. Its successors saw combat for the first time the following year at the Battle of the Somme. The invention marked the birth of armored warfare, which would transform battlefields for the rest of the century.

The Royal Air Force suffers its first fighter pilot casualty of the Second World War in a friendly-fire incident over the Thames Estuary.

Radar operators mistakenly reported an incoming raid, prompting RAF Hurricanes to scramble and, in the ensuing confusion, mistakenly attack a squadron of British Spitfires. Pilot Officer Montague Hulton-Harrop was killed in the episode, later dubbed the 'Battle of Barking Creek.' The incident exposed serious flaws in Britain's fledgling early-warning radar and fighter-control systems just days into the war, prompting urgent reforms.

A de Havilland DH.110 prototype breaks apart during a display at the Farnborough Airshow in England, killing the two crew and 29 spectators.

The aircraft disintegrated in mid-air after exceeding its structural limits during a demonstration, scattering wreckage and engine debris into the crowd below. It remains one of the deadliest air show disasters in history. Remarkably, the show continued the same day, but the crash prompted lasting changes to display flying rules and closer scrutiny of experimental aircraft testing near spectators in Britain.

Workers excavating the Thames foreshore in London discover the wreck of a Roman-era cargo ship.

Known as Blackfriars Ship I, the vessel dated from the second century AD and had been used to transport building stone along the river, offering rare physical evidence of Roman London's river trade. Its timbers, remarkably well preserved in the Thames mud, were carefully recorded and conserved. The find remains one of the most significant Roman archaeological discoveries made in the City of London.

Swaziland gains full independence from Britain, becoming a sovereign kingdom under King Sobhuza II.

The small southern African territory had been a British protectorate since the late nineteenth century, administered separately from neighboring South Africa. Independence came amid a wave of decolonization across the British Empire in the 1960s, as Britain relinquished direct control over most of its African territories. The country was later renamed Eswatini in 2018 to mark fifty years of independence.

Palestinian militants take Israeli athletes hostage at the Munich Olympics, resulting in the deaths of nine athletes in what becomes known as the Munich massacre.

During the Munich Summer Olympics, members of the Palestinian militant group Black September infiltrated the Olympic Village, killing two Israeli team members immediately and taking nine others hostage. A botched rescue attempt at a nearby airport resulted in the deaths of all nine remaining hostages, along with a German police officer and five of the eight attackers.

The Soviet Union formally recognizes the independence of the three Baltic states.

As the Soviet Union's central authority rapidly disintegrated following the failed August coup against Mikhail Gorbachev, the State Council of the USSR formally acknowledged the restored independence of Estonia, Latvia, and Lithuania, nations that had been forcibly annexed by the Soviet Union in 1940. Their independence was quickly recognized internationally as well.

The funeral of Diana, Princess of Wales, is held at Westminster Abbey in London, watched by an estimated global television audience of over two billion.

Diana had died in a car crash in Paris six days earlier, unleashing an extraordinary outpouring of public grief across Britain that put unprecedented pressure on the royal family to respond publicly. Her brother Earl Spencer delivered a pointed eulogy criticizing the media, while crowds lined the funeral route in London. The event remains one of the most-watched broadcasts in television history.

Liz Truss becomes Prime Minister of the United Kingdom, succeeding Boris Johnson.

Following Boris Johnson's resignation amid mounting political scandals, Liz Truss traveled to Balmoral Castle to be formally appointed prime minister by Queen Elizabeth II, in what would prove to be one of the monarch's final official acts before her death just two days later. Truss's own tenure in office lasted only 49 days, the shortest of any British prime minister in history.

Boris Johnson formally resigns as Prime Minister, travelling to Balmoral to tender his resignation to Queen Elizabeth II as Liz Truss takes office.

Johnson had announced his intention to step down two months earlier after a wave of ministerial resignations over his handling of scandals, including lockdown-breaking parties in Downing Street during the pandemic. The Conservative Party's membership had since elected Liz Truss as his successor. It was one of the Queen's final official duties, appointing her fifteenth prime minister just two days before her death.