This Day in History

April 20


1303      Sapienza University of Rome founded by papal bull—oldest of Rome's four state-funded universities   716
1472      Italian architect and polymath Leon Battista Alberti dies in Rome, age 68   547
1526      Ibrahim Lodi is defeated and killed by the Mughai in first Battle of Panipat ending the Lodi Dynasty in central India   493
1653      Oliver Cromwell dissolves Parliament—the Rump Parliament   366
1657      English fleet under Robert Blake destroys a Spanish treasure fleet at Santa Cruz de Tenerife in the Spanish Canary Islands   362
1769      Odawa war chief Pontiac or Obwandiyag) dies, age about 49   250
1792      France declares war on Austria initiating the French Revolutionary wars   227
1828      French explorer René Caillié becomes the first European to enter Timbouctou and leave alive   191
1861      Robert E. Lee resigns his commission from the U.S. Army in order to lead forces of the state of Virginia   158
1862      Louis Pasteur and Claude Bernard complete experiments leading to pasteurization   157
1876      American Chemical society is organized in New York City   143
1898      President William McKinley signs a joint resolution to Congress declaring war against Spain—beginning the Spanish-American War   121
1902      Marie and Pierre Curie isolate the element Radium   117
1908      English-born American sportswriter and pioneer baseball statistician Henry Chadwick dies in Brooklyn, age 83   111
1908      William J. Keith born in Tennessee   111
1909      Tel Aviv is founded near the ancient port city of Jaffa (Joppa)   110
1912      Irish novelist Bram Stoker dies in London, age 64   107
1912      Fenway Park in Boston opens—oldest Major League Baseball stadium and oldest U.S. professional sports venue still in use   107
1916      Cubs play their first game at what is now Wrigley Field—defeat Reds 7-6   103
1918      German inventor, physicist and Nobel laureate (1909) Karl Ferdinand Braun dies in New York City, age 67   101
1932      Italian mathematician Giuseppe Peano dies in Turin, age 73   87
1946      League of Nations formally ceases to exist   73
1961      Harold Graham makes first free flight of a personal rocket jetpack   58
1961      failure of the Bay of Pigs invasion of U.S.-backed Cuban exiles against Cuba   58
1966      Surveyor 3 lands on the moon   53
1972      Apollo 16—John Young and Charles Duke land on moon   47
1982      American poet and writer Archibald MacLeish dies in Boston, age 89   37
   an Anniversary!! 
1999      tragedy at Columbine High School in Littleton, Colorado—15 killed and 24 others injured   20
2001      Italian conductor and composer Giuseppe Sinopoli dies in Berlin, age 54   18
2003      German-born biophysicist and Nobel laureate (1970) Bernard Katz dies in London, age 92   16
2004      launch of Gravity Probe B (GP-B)   15
2007      last issue of Life Magazine—continues only as a web presence   12
2008      Danica Patrick becomes the first woman to win an Indy car race—Indy Japan 500   11
2010      American administrator and civil rights and women's rights activist Dorothy Irene Height dies in Washington D.C., age 98   9
2010      oil well blowout destroys the Deepwater Horizon oil drilling platform in the Gulf of Mexico   9
2011      British photojournalist Timothy "Tim" Alistair Telemachus Hetherington dies in Libya, age 40   8
2011      robot throws out the ceremonial first pitch for a Brewers at Phillies game—is booed by Phillies fans   8
2011      Prince Charles becomes the longest-serving heir apparent in British history surpassing Edward VII   8
2012      last reactor in Japan's Fukushima Daiichi Nuclear Power Plant is shut down   7
2013      7.0 earthquake strikes in Lushan County in China—almost 200 die and over 15,000 others injured   6
2014      Curiosity takes the first photographs of asteroids from the surface of Mars—Ceres and Vesta   5
2015      Texas based Blue Bell Creameries voluntarily recalls ice cream and other products because of the potential of Listeria contamination   4
2016      English comedian, actress, singer and songwriter, screenwriter, producer, and director Victoria Wood dies in London, age 62   3
2016      U.S. Treasury announces that Andrew Jackson's face on the $20 bill will be replaced by the face of Harriet Tubman   3
2017      China launches Tianzhou-1 cargo spacecraft with a Long March 7 to dock with China's second prototype space station Tiangong-2   2
   420, day associated with cannabis-oriented celebrations 

Dates are always somewhat ambiguous, the exact date depends on whether local time is used (and local time where) or Universal Time—for events on the surface of the Earth, local time is probably best but for an event that spans across the planet, it is not clear which local time to use!. For events in space it is more ambiguous. Further for dates after the original adoption of the Gregorian calendar but before it became accepted in different countries, the date given may be a Julian date or a Gregorian date depending upon where the event occurred. And, even the year may be different since the first of the year has not always been January 1 in all countries! The attempt is to use a date that is the one that is typically given.

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