September 12

Athenian forces and their Plataean allies defeat the first Persian invasion of Greece at the Battle of Marathon.

A vastly outnumbered Athenian army, aided by allies from the small city of Plataea, decisively defeated the first Persian invasion force on the plain of Marathon, employing an innovative tactical formation that enveloped the Persian flanks. The victory is often cited as a pivotal moment preserving early Greek civilization and democratic experimentation from Persian conquest.

Henry Hudson begins exploring the river later named after him while commanding the Halve Maen.

Sailing for the Dutch East India Company while searching for a northwest passage to Asia, English navigator Henry Hudson instead explored the river later named in his honor, extensively charting the waterway and establishing early Dutch claims to the region that became New Netherland.

American forces halt the British advance toward Baltimore at the Battle of North Point during the War of 1812.

American militia and regular troops repelled a British advance toward Baltimore at North Point, inflicting casualties including the death of the British commanding general, a defensive stand that helped set the stage for the successful defense of nearby Fort McHenry the following day.

The Battle of Chapultepec begins during the Mexican-American War.

American forces under General Winfield Scott launched an assault on the fortified hilltop castle of Chapultepec, then serving as Mexico's military academy, in one of the final major battles before the fall of Mexico City during the Mexican-American War. The castle's defenders included young military cadets who fought fiercely, and the battle's outcome opened the road directly into the Mexican capital.

The steamship SS Central America sinks off North Carolina, carrying a significant shipment of California gold.

Overloaded with passengers and a substantial cargo of gold from the California mines, the steamship SS Central America sank during a hurricane off the Carolina coast, killing over 400 people in one of the deadliest peacetime maritime disasters in American history to that point.

The Newport Transporter Bridge opens in Wales.

Designed to allow crossing traffic while permitting tall ships to pass beneath, the transporter bridge suspended a moving gondola from an overhead framework above the River Usk in Newport, Wales, an unusual engineering solution that remains a distinctive local landmark.

Future president John F. Kennedy marries Jacqueline Lee Bouvier in Newport, Rhode Island.

The future president married Jacqueline Bouvier in a highly publicized society wedding at St. Mary's Church in Newport, Rhode Island, an event that drew significant media attention and helped establish the glamorous public image that would later characterize the Kennedy White House.

President Kennedy delivers his "We choose to go to the Moon" speech at Rice University.

Addressing a large crowd at Rice University, President Kennedy articulated his ambitious vision for landing Americans on the Moon within the decade, famously declaring the nation chose to pursue the goal "not because it is easy, but because it is hard," galvanizing public and congressional support for the Apollo program.

A treaty authorizing German reunification is signed in Moscow.

Representatives of East and West Germany along with the four World War II Allied powers signed the Treaty on the Final Settlement, formally clearing the way for German reunification just weeks later, officially ending the postwar division that had defined Cold War Europe for over four decades.

NASA confirms that its Voyager 1 probe had become the first human-made object to enter interstellar space.

NASA scientists analyzing data from the Voyager 1 spacecraft confirmed that the probe had crossed the heliopause roughly a year earlier, becoming the first human-made object to leave the protective bubble of charged particles surrounding the solar system and enter true interstellar space.