October 20 in History

Alonso de Mendoza founded La Paz in a valley 11,975 feet above sea level on orders from Charles V. He named it Nuestra Señora de La Paz—Our Lady of Peace—because it was founded after a civil war between Spanish conquistadors ended. It's the highest administrative capital on Earth. The city was built where it was to avoid the wind on the plateau above.

Maria Theresa inherited the Austrian throne in 1740 at age 23. Her father had spent years securing promises that Europe would accept a female ruler. France, Prussia, Bavaria, and Saxony broke their word within weeks. Frederick the Great invaded Silesia two months later. The War of Austrian Succession lasted eight years. She lost territory but kept her throne. She ruled for 40 years.

The First Continental Congress adopts the Continental Association, binding thirteen colonies to boycott British goods and halt all trade with the British Isles and West Indies. This unified economic weapon forces Britain to confront colonial resistance as a collective threat rather than isolated grievances, setting the stage for total war.

Britain and the United States signed the Convention of 1818, setting their border at the 49th parallel from the Lake of the Woods to the Rocky Mountains. The agreement left the Oregon Territory jointly occupied — both nations could settle there. That arrangement lasted until 1846, when they extended the 49th parallel to the Pacific. The border runs 5,525 miles, mostly undefended.

The Battle of Navarino in 1827 saw a combined British, French, and Russian naval force decisively defeat a Turkish and Egyptian armada in Greece. This victory was significant in the context of the Greek War of Independence, as it helped secure Greek autonomy and demonstrated the influence of European powers in the region.

A combined British, French, and Russian fleet annihilated the Ottoman-Egyptian armada at Navarino Bay in the last major naval battle fought entirely under sail. The decisive victory broke Ottoman naval power in the eastern Mediterranean and secured Greek independence after nearly four centuries of Turkish rule.

Yale, Princeton, Columbia, and Rutgers met and wrote the first American football rules. They limited teams to 11 players. They made the field 140 yards long. They kept rugby's scoring system. Harvard refused to attend—they were playing a different game. The rules lasted two years before being rewritten. Soccer and rugby had split in England just nine years earlier.

Peru ceded the Tarapacá province to Chile in the Treaty of Ancón in 1883, ending its involvement in the War of the Pacific. Chile had occupied Lima for two years. Tarapacá held massive nitrate deposits — the oil of the 19th century, used for fertilizer and explosives. Peru lost its richest resource zone. Bolivia lost its entire coastline in the same war. It's still landlocked.

The hull of RMS Olympic launched from Harland and Wolff's Belfast shipyard in 1910. It was the largest moving object ever built. The launch took 62 seconds. Olympic entered service in 1911, a year before her sister Titanic. She survived a collision with a warship, struck a U-boat, and served as a troopship in World War I. She was scrapped in 1935 after 24 years of service. Titanic lasted five days.

German soldiers executed between 2,000 and 5,000 civilians in Kragujevac, Serbia, in 1941 as retaliation for partisan attacks that killed 10 German soldiers. Wehrmacht orders specified 100 Serbs shot for every German killed. Soldiers pulled students from classrooms. The massacre lasted all day. One German officer refused to participate and was arrested. The city's population was 23,000. Nearly every family lost someone.