July 15

The Temple of Castor and Pollux is dedicated in the Roman Forum.

After a difficult five-week siege, Crusader forces breached the walls of Jerusalem and captured the city, followed by a notorious massacre of many of its Muslim and Jewish inhabitants. The conquest established the Crusader Kingdom of Jerusalem, the primary political entity of the Crusader states in the Levant for nearly a century afterward.

Crusader forces capture Jerusalem after a difficult siege, establishing the Crusader-controlled Kingdom of Jerusalem.

A combined army of Polish, Lithuanian, and allied forces decisively defeated the Teutonic Knights near the villages of Grunwald and Tannenberg in one of medieval Europe's largest battles. The victory broke the military dominance of the Teutonic Order in the region and marked a turning point in Polish-Lithuanian power in Central Europe.

Combined Polish-Lithuanian forces decisively defeat the Teutonic Knights at the Battle of Grunwald.

During Napoleon's Egyptian campaign, French soldiers rebuilding a fort near the town of Rosetta unearthed a stone slab inscribed with the same text in three scripts, including ancient Greek and Egyptian hieroglyphs. The find later enabled scholars, most notably Jean-Francois Champollion, to finally decipher hieroglyphic writing after centuries of mystery.

French soldiers accompanying Napoleon's Egyptian campaign discover the Rosetta Stone, a find that later enabled the decipherment of Egyptian hieroglyphs.

Following his final defeat at Waterloo weeks earlier, Napoleon boarded the British warship HMS Bellerophon and surrendered himself to British custody, hoping for asylum in England. Instead, he was exiled to the remote South Atlantic island of Saint Helena, where he spent his remaining years and died in 1821.

Napoleon Bonaparte formally surrenders to British forces aboard HMS Bellerophon, ending his final bid for power.

After more than three centuries of operation targeting heresy and religious dissent within Spain and its territories, the Spanish Inquisition was formally abolished by royal decree, reflecting the liberal political reforms sweeping Spain in the early nineteenth century following the Napoleonic Wars and subsequent constitutional movements.

The Spanish Inquisition is officially disbanded after operating for approximately 356 years.

A powerful volcanic eruption at Mount Bandai in northern Japan devastated surrounding villages, triggering landslides and destroying homes and farmland. The disaster killed several hundred people and prompted early Japanese scientific study of volcanic hazards, influencing later disaster preparedness policy in the region.

Mount Bandai erupts violently in Japan, killing roughly 500 people in Fukushima Prefecture.

German forces launched what became their final major offensive of World War I along the Marne River in France, but Allied troops, bolstered by American reinforcements, halted the advance and soon counterattacked. The battle marked the definitive turning of the tide against Germany on the Western Front, leading toward the war's end that November.

The Second Battle of the Marne begins near the Marne River in France, a major Allied victory that turned the tide of World War I.

American and Soviet spacecraft launched separately before docking in orbit two days later, the first joint human spaceflight mission between the two Cold War rivals. Conceived as a symbol of détente, the mission featured astronauts and cosmonauts conducting joint experiments and handshakes broadcast worldwide, easing tensions in the ongoing space race.

The Apollo-Soyuz Test Project launches, marking the first joint American-Soviet human spaceflight mission.

Founders Jack Dorsey, Biz Stone, and Evan Williams launched a short-message social platform originally limited to 140 characters, inspired partly by SMS text messaging. Twitter rapidly grew into a globally influential communication tool used for everything from personal updates to breaking news and political discourse, later rebranded as X in 2023.

The social media platform Twitter is publicly launched.

Ancient Roman tradition held an annual procession honoring the twin gods Castor and Pollux on the anniversary of their temple's dedication in the Forum, commemorating their legendary aid to Rome in an early battle. The temple remained a significant religious and civic site in Roman public life for centuries.