August 13

Octavian celebrates the first of three consecutive triumphs in Rome, honoring his victory over Dalmatian tribes.

As part of a series of celebrations honoring his consolidation of power following years of civil war, Octavian held the first of three consecutive days of triumphal processions through Rome, this one specifically commemorating his military campaigns against rebellious Dalmatian tribes in the Balkans.

King Henry V of England lands in France, beginning the campaign that leads to Agincourt.

Renewing English claims to the French throne amid the ongoing Hundred Years' War, King Henry V landed with an invasion force in Normandy. His subsequent campaign culminated two months later in the decisive English victory at the Battle of Agincourt, one of the most celebrated military triumphs in English history.

Hernan Cortes's forces capture Aztec ruler Cuauhtemoc, completing the conquest of Tenochtitlan.

Following a prolonged siege and fierce urban combat, Spanish conquistador Hernan Cortes and his indigenous allies captured the last Aztec emperor, Cuauhtemoc, marking the definitive fall of the Aztec capital Tenochtitlan. The conquest opened the way for Spanish colonization of central Mexico and the eventual establishment of New Spain.

The Duchy of Brittany is formally absorbed into the Kingdom of France.

Through a combination of dynastic marriage and eventual royal decree, the previously semi-autonomous Duchy of Brittany was formally and permanently incorporated into the Kingdom of France, ending Brittany's long history as a distinct political entity while allowing it to retain certain regional privileges.

English and Imperial forces defeat French and Bavarian troops at the Battle of Blenheim.

A coalition army led by the Duke of Marlborough and Prince Eugene of Savoy decisively defeated French and Bavarian forces near the Bavarian village of Blenheim during the War of the Spanish Succession, halting a planned French advance on Vienna and marking one of the most significant military victories in British history to that point.

King Louis XVI is formally arrested and declared an enemy of the French people.

As the French Revolution radicalized further, the royal family, having earlier attempted to flee the country, was formally arrested and imprisoned in the Temple fortress, with the National Assembly declaring the monarchy effectively suspended. Louis XVI was later tried and executed the following January.

Wagner's opera "Das Rheingold" premieres at the inaugural Bayreuth Festival, opening the first complete Ring cycle.

Richard Wagner's monumental four-opera cycle "Der Ring des Nibelungen" began its first complete public performance with the premiere of its opening installment, "Das Rheingold," at the purpose-built Bayreuth Festspielhaus. Wagner had designed the theater specifically to showcase his ambitious operatic works, incorporating an unusually deep, hidden orchestra pit that became a hallmark of the venue and influenced opera house design for generations afterward.

East Germany closes the border between East and West Berlin, beginning construction of the Berlin Wall.

Amid a growing exodus of East Germans fleeing to the West through Berlin, East German authorities abruptly sealed the border between the city's eastern and western sectors with barbed wire, which was soon replaced by a more permanent concrete barrier. The Berlin Wall stood as a stark symbol of Cold War division for the next 28 years.

Apollo 11 astronauts are honored with a ticker-tape parade in New York and later receive the Presidential Medal of Freedom.

Following their historic Moon landing days earlier, Apollo 11 astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins were celebrated with massive ticker-tape parades in New York and Chicago before being honored at a state dinner where President Nixon awarded them the Presidential Medal of Freedom.

Israel and the United Arab Emirates formally establish diplomatic relations.

Brokered in part through the Abraham Accords negotiated by the Trump administration, Israel and the United Arab Emirates announced the normalization of formal diplomatic relations, making the UAE only the third Arab nation to establish such ties with Israel, following Egypt and Jordan decades earlier.