October 20 events in history

1548 The city of Nuestra Señora de La Paz (Our Lady of Peace) is founded by Alonso de Mendoza by appointment of the king of Spain and Holy Roman Emperor, Charles V
1572 Relief of Goes, Cristóbal de Mondragón with 3000 soldiers of the Spanish Tercios, release the siege of the city
1720 Caribbean pirate Calico Jack is captured by the Royal Navy
1740 Maria Theresa takes the throne of Austria. France, Prussia, Bavaria and Saxony refuse to honour the Pragmatic Sanction and the War of the Austrian Succession begins
1781 Patent of Toleration, providing limited freedom of worship, is approved in Habsburg Monarchy
1803 The United States Senate ratifies the Louisiana Purchase
1818 The Convention of 1818 signed between the United States and the United Kingdom which, among other things, settles the Canada–United States border on the 49th parallel for most of its length
1827 Battle of Navarino: a combined Turkish and Egyptian armada is defeated by British, French, and Russian naval force in the port of Navarino in Pylos, Greece
1873 Yale, Princeton, Columbia, and Rutgers universities draft the first code of American football rules
1883 Peru and Chile sign the Treaty of Ancón, by which the Tarapacá province is ceded to the latter, bringing an end to Peru's involvement in the War of the Pacific
1904 Chile and Bolivia sign the Treaty of Peace and Friendship, delimiting the border between the two countries
1910 The hull of the RMS Olympic, sister-ship to the ill-fated RMS Titanic, is launched from the Harland and Wolff shipyard in Belfast, Northern Ireland
1935 The Long March, a mammoth retreat undertaken by the armed forces of the Chinese Communist Party a year prior, ends
1939 Pope Pius XII publishes his first major encyclical entitled Summi Pontificatus
1941 World War II: Thousands of civilians in Kragujevac in German-occupied Serbia are murdered in the Kragujevac massacre
1943 The cargo vessel Sinfra is attacked by Allied aircraft at Souda Bay, Crete, and sunk. 2,098 Italian prisoners of war drown with it
1944 The Soviet Army and Yugoslav Partisans liberate Belgrade, the capital of Yugoslavia
1944 Liquid natural gas leaks from storage tanks in Cleveland, then explodes; the explosion and resulting fire level 30 blocks and kill 130
1944 American general Douglas MacArthur fulfills his promise to return to the Philippines when he commands an Allied assault on the islands, reclaiming them from the Japanese during the Second World War
1946 Government of the Democratic Republic of Vietnam decides that October 20 is Vietnam Women's Day
1947 The House Un-American Activities Committee begins its investigation into Communist infiltration of Hollywood, resulting in a blacklist that prevents some from working in the industry for years
1947 United States of America and Islamic Republic of Pakistan establish diplomatic relations for the first time
1951 The "Johnny Bright incident" occurs in Stillwater, Oklahoma
1952 Governor Evelyn Baring declares a state of emergency in Kenya and begins arresting hundreds of suspected leaders of the Mau Mau Uprising, including Jomo Kenyatta, the future first President of Kenya
1961 The Soviet Union performs the first armed test of a submarine-launched ballistic missile, launching an R-13 from a Golf-class submarine
1962 People's Republic of China launches simultaneous offensives in Ladakh and across the McMahon Line, igniting the Sino-Indian War
1968 Former First Lady Jacqueline Kennedy marries Greek shipping tycoon Aristotle Onassis
1970 Siad Barre declares Somalia a socialist state
1971 The Nepal Stock Exchange collapses
1973 "Saturday Night Massacre": United States President Richard Nixon fires U.S. Attorney General Elliot Richardson and Deputy Attorney General William Ruckelshaus after they refuse to fire Watergate special prosecutor Archibald Cox, who is finally fired by Robert Bork
1973 The Sydney Opera House opens
1976 The ferry George Prince is struck by a ship while crossing the Mississippi River between Destrehan and Luling, Louisiana. Seventy-eight passengers and crew die and only 18 people aboard the ferry survive
1977 Rock band Lynyrd Skynyrd's plane crashes
1981 Two police officers and an armored car guard are killed during an armed robbery in Rockland County, New York, carried out by members of the Black Liberation Army and Weather Underground
1982 During the UEFA Cup match between FC Spartak Moscow and HFC Haarlem, 66 people are crushed to death in the Luzhniki disaster
1991 The Oakland Hills firestorm kills 25 and destroys 3,469 homes and apartments, causing more than $2 billion in damage
1991 A 6.8 Mw earthquake strikes the Uttarkashi region of India, killing more than 1,000 people
2011 Libyan Civil War: National Transitional Council rebel forces capture ousted Libyan dictator Muammar Gaddafi in his hometown of Sirte and kill him shortly thereafter