1303 – The Sapienza University of Rome is instituted by a bull of Pope Boniface VIII.
1453 – Three Genoese galleys and a Byzantine blockade runner fight their way through an Ottoman blockading fleet a few weeks before the fall of Constantinople.
1534 – Jacques Cartier begins his first voyage to what is today the east coast of Canada, Newfoundland and Labrador.
1535 – The sun dog phenomenon is observed over Stockholm, as later depicted in the famous painting Vädersolstavlan.
1653 – Oliver Cromwell dissolves the Rump Parliament.
1657 – Admiral Robert Blake destroys a Spanish silver fleet under heavy fire at the Battle of Santa Cruz de Tenerife.
1657 – Freedom of religion is granted to the Jews of New Amsterdam (later New York City).
1689 – Deposed monarch James II of England lays siege to Derry.
1752 – Start of Konbaung–Hanthawaddy War, a new phase in the Burmese Civil War (1740–57).
1770 – The Georgian king, Erekle II, abandoned by his Russian ally Count Totleben, wins a victory over Ottoman forces at Aspindza.
1775 – American Revolutionary War: The Siege of Boston begins, following the battles at Lexington and Concord.
1789 – George Washington arrives at Grays Ferry, Philadelphia while en route to Manhattan for his inauguration.
1792 – France declares war against the “King of Hungary and Bohemia”, the beginning of French Revolutionary Wars.
1800 – The Septinsular Republic is established.
1809 – Two Austrian army corps in Bavaria are defeated by a First French Empire army led by Napoleon at the Battle of Abensberg on the second day of a four-day campaign that ended in a French victory.
1810 – The governor of Caracas, Venezuela declares independence from Spain.
1818 – The case of Ashford v Thornton ends, with Abraham Thornton allowed to go free rather than face a retrial for murder, after his demand for trial by battle is upheld.
1828 – René Caillié becomes the second non-Muslim to enter (and the first to return from) Timbuktu, following Major Gordon Laing.
1836 – U.S. Congress passes an act creating the Wisconsin Territory.
1861 – American Civil War: Robert E. Lee resigns his commission in the United States Army in order to command the forces of the state of Virginia.
1862 – Louis Pasteur and Claude Bernard complete the experiment disproving the theory of spontaneous generation.
1865 – Astronomer Angelo Secchi demonstrates the Secchi disk, which measures water clarity, aboard Pope Pius IX’s yacht, the L’Immaculata Concezion.
1876 – The April Uprising begins. Its suppression shocks European opinion, and Bulgarian independence becomes a condition for ending the Russo-Turkish War.
1884 – Pope Leo XIII publishes the encyclical Humanum genus.
1898 – U.S. President William McKinley signed a joint resolution to Congress for declaration of war against Spain, beginning the Spanish–American War.
1902 – Pierre and Marie Curie refine radium chloride.
1908 – Opening day of competition in the New South Wales Rugby League.
1912 – Opening day for baseball’s Tiger Stadium in Detroit, and Fenway Park in Boston.
1914 – Nineteen men, women, and children die in the Ludlow Massacre during a Colorado coal-miners’ strike.
1916 – The Chicago Cubs play their first game at Weeghman Park (currently Wrigley Field), defeating the Cincinnati Reds 7–6 in 11 innings.
1918 – Manfred von Richthofen, a.k.a. The Red Baron, shoots down his 79th and 80th victims, his final victories before his death the following day.
1922 – The Soviet government creates South Ossetian Autonomous Oblast within Georgian SSR.
1939 – Adolf Hitler’s 50th birthday’s celebrations in Germany
1945 – World War II: U.S. troops capture Leipzig, Germany, only to later cede the city to the Soviet Union.
1945 – World War II: Führerbunker: On his 56th birthday Adolf Hitler makes his last trip to the surface to award Iron Crosses to boy soldiers of the Hitler Youth.
1945 – Twenty Jewish children used in medical experiments at Neuengamme are killed in the basement of the Bullenhuser Damm school.
1946 – The League of Nations officially dissolves, giving most of its power to the United Nations.
1961 – Cold War: Failure of the Bay of Pigs Invasion of US-backed Cuban exiles against Cuba.
1968 – English politician Enoch Powell makes his controversial “Rivers of Blood” speech.
1972 – Apollo program: Apollo 16 lunar module, commanded by John Young and piloted by Charles Duke, lands on the moon.
1998 – Air France Flight 422 crashes after taking off from El Dorado International Airport in Bogotá, Colombia, killing all 53 people on board.
1999 – Columbine High School massacre: Eric Harris and Dylan Klebold kill 13 people and injure 24 others before committing suicide at Columbine High School in Columbine, Colorado.
2007 – Johnson Space Center shooting: William Phillips with a handgun barricade himself in NASA’s Johnson Space Center in Houston, Texas before killing a male hostage and himself.
2008 – Danica Patrick wins the Indy Japan 300 becoming the first female driver in history to win an Indy car race.
2010 – The Deepwater Horizon drilling rig explodes in the Gulf of Mexico, killing eleven workers and beginning an oil spill that would last six months.
2012 – One hundred twenty-seven people are killed when a plane crashes in a residential area near the Benazir Bhutto International Airport near Islamabad, Pakistan.
2013 – A 6.6-magnitude earthquake strikes Lushan County, Ya’an, in China’s Sichuan province, killing more than 150 people and injuring thousands.
2015 – Ten people are killed in a bomb attack on a convoy carrying food supplies to a United Nations compound in Garowe in the Somali region of Puntland.
Births on April 20
1494 – Johannes Agricola, German theologian and reformer (d. 1566)
1544 – Renata of Lorraine, Duchess consort of Bavaria (d. 1602)
1586 – Rose of Lima, Peruvian mystic and saint (d. 1617)
1633 – Emperor Go-Kōmyō of Japan (d. 1654)
1646 – Charles Plumier, French botanist and author (d. 1704)
1650 – William Bedloe, English spy (d. 1680)
1718 – David Brainerd, American missionary (d. 1747)
1723 – Cornelius Harnett, American merchant, farmer, and politician (d. 1781)
1727 – Florimond Claude, Comte de Mercy-Argenteau, Belgian-Austrian minister and diplomat (d. 1794)
1745 – Philippe Pinel, French physician and psychiatrist (d. 1826)
1748 – Georg Michael Telemann, German composer and theologian (d. 1831)
1772 – William Lawless, Irish revolutionary and French general (d. 1824)
1808 – Napoleon III, French politician, 1st President of France (d. 1873)
1816 – Bogoslav Šulek, Croatian philologist, historian, and lexicographer (d. 1895)
1818 – Heinrich Göbel, German-American mechanic and engineer (d. 1893)
1826 – Dinah Craik, English author and poet (d. 1887)
1836 – Eli Whitney Blake, Jr., American scientist and academic (d. 1895)
1839 – Carol I of Romania, King of Romania (d. 1914)
1840 – Odilon Redon, French painter and illustrator (d. 1916)
1850 – Daniel Chester French, American sculptor, designed the Lincoln statue (d. 1931)
1851 – Alexander Dianin, Russian chemist (d. 1918)
1851 – Siegmund Lubin, Polish-American businessman, founded the Lubin Manufacturing Company (d. 1923)
1860 – Justinien de Clary, French target shooter (d. 1933)
1871 – Sydney Chapman, English economist and civil servant (d. 1951)
1873 – James Harcourt, English character actor (d. 1951)
1875 – Vladimir Vidrić, Croatian poet and lawyer (d. 1909)
1879 – Paul Poiret, French fashion designer (d. 1944)
1882 – Holland Smith, American general (d. 1967)
1884 – Princess Beatrice of Saxe-Coburg and Gotha (d. 1966)
1884 – Oliver Kirk, American boxer (d. 1960)
1884 – Daniel Varoujan, Armenian poet and educator (d. 1915)
1889 – Albert Jean Amateau, Turkish rabbi, lawyer, and activist (d. 1996)
1889 – Prince Erik, Duke of Västmanland (d. 1918)
1889 – Marie-Antoinette de Geuser, French mystic (d. 1918)
1889 – Adolf Hitler, Austrian born German politician, Führer of Nazi Germany (d. 1945)
1889 – Tonny Kessler, Dutch footballer (d. 1960)
1890 – Maurice Duplessis, Canadian lawyer and politician, 16th Premier of Quebec (d. 1959)
1890 – Adolf Schärf, Austrian soldier and politician, 6th President of Austria (d. 1965)
1891 – Dave Bancroft, American baseball player and manager (d. 1972)
1893 – Harold Lloyd, American actor, comedian, and producer (d. 1971)
1893 – Joan Miró, Spanish painter and sculptor (d. 1983)
1895 – Emile Christian, American trombonist and composer (d. 1973)
1895 – Henry de Montherlant, French essayist, novelist, and dramatist (d. 1972)
1896 – Wop May, Canadian captain and pilot (d. 1952)
1899 – Alan Arnett McLeod, Canadian lieutenant, Victoria Cross recipient (d. 1918)
1904 – Bruce Cabot, American actor (d. 1972)
1907 – Miran Bux, Pakistani cricketer (d. 1991)
1907 – Augoustinos Kantiotes, Greek bishop (d. 2010)
1908 – Lionel Hampton, American vibraphone player, pianist, bandleader, and actor (d. 2002)
1910 – Fatin Rüştü Zorlu, Turkish diplomat and politician (d. 1961)
1913 – Mimis Fotopoulos, Greek actor and poet (d. 1986)
1913 – Willi Hennig, German biologist and entomologist (d. 1976)
1913 – Roger Rochard, French runner (d. 1993)
1914 – Betty Lou Gerson, American actress (d. 1999)
1915 – Joseph Wolpe, South African psychotherapist and physician (d. 1997)
1916 – Nasiba Zeynalova, Azerbaijani actress (d. 2004)
1918 – Kai Siegbahn, Swedish physicist and academic, Nobel Prize laureate (d. 2007)
1919 – Richard Hillary, Australian lieutenant and pilot (d. 1943)
1920 – Frances Ames, South African neurologist, psychiatrist, and human rights activist (d. 2002)
1920 – Clement Isong, Nigerian banker and politician, Governor of Cross River State (d. 2000)
1920 – Ronald Speirs, American colonel (d. 2007)
1920 – John Paul Stevens, American lawyer and jurist, Associate Justice of the Supreme Court of the United States (d. 2019)
1923 – Mother Angelica, American nun and broadcaster, founded Eternal Word Television Network (d. 2016)
1923 – Irene Lieblich, Polish-American painter and illustrator (d. 2008)
1923 – Tito Puente, American drummer and producer (d. 2000)
1924 – Nina Foch, Dutch-American actress (d. 2008)
1924 – Leslie Phillips, English actor and producer
1924 – Guy Rocher, Canadian sociologist and academic
1925 – Ernie Stautner, German-American football player and coach (d. 2006)
1925 – Elena Verdugo, American actress (d. 2017)
1927 – Bud Cullen, Canadian judge and politician, 1st Canadian Minister of Employment and Immigration (d. 2005)
1927 – Phil Hill, American race car driver (d. 2008)
1927 – K. Alex Müller, Swiss physicist and academic, Nobel Prize laureate
1928 – Robert Byrne, American chess player and author (d. 2013)
1928 – Johnny Gavin, Irish international footballer (d. 2007)
1929 – Harry Agganis, American baseball and football player (d. 1955)
1929 – Bobby Hollander, American film director, actor, and magazine publisher (d. 2002)
1930 – Dwight Gustafson, American composer and conductor (d. 2014)
1930 – Antony Jay, English director and screenwriter (d. 2016)
1931 – Michael Allenby, 3rd Viscount Allenby, English lieutenant and politician (d. 2014)
1931 – John Eccles, 2nd Viscount Eccles, English businessman and politician
1932 – Myriam Bru, French actress
1933 – Kristaq Dhamo, Albanian actor and film director
1936 – Lisa Davis, English and American former child and adult actress
1936 – Pauli Ellefsen, Faroese technician, surveyor, and politician, 6th Prime Minister of the Faroe Islands (d. 2012)
1936 – Pat Roberts, American captain, journalist, and politician
1936 – Christopher Robinson, English organist and conductor
1937 – Jiří Dienstbier, Czech journalist and politician, Czech Minister of Foreign Affairs (d. 2011)
1937 – Antonios Kounadis, Greek discus thrower
1937 – Harvey Quaytman, American painter and educator (d. 2002)
1937 – George Takei, American actor
1938 – Betty Cuthbert, Australian sprinter
1938 – Manfred Kinder, German runner
1938 – Peter Snow, British historian and journalist
1938 – Eszter Tamási, Hungarian actress (d. 1991)
1939 – Elspeth Ballantyne, Australian actress
1939 – Peter S. Beagle, American author and screenwriter
1939 – Gro Harlem Brundtland, Norwegian physician and politician, 22nd Prime Minister of Norway
1939 – Johnny Tillotson, American singer-songwriter
1940 – James Gammon, American actor (d. 2010)
1941 – Ryan O’Neal, American actor
1942 – Giles Henderson, English lawyer and academic
1942 – Arto Paasilinna, Finnish journalist and author
1943 – Alan Beith, English academic and politician
1943 – John Eliot Gardiner, English conductor and director
1943 – Edie Sedgwick, American model and actress (d. 1971)
1944 – Toivo Aare, Estonian journalist and author (d. 1999)
1945 – Michael Brandon, American actor and director
1945 – Olga Karlatos, Greek actress and Bermudian lawyer
1945 – Thein Sein, Burmese general and politician, 8th President of Burma
1945 – Naftali Temu, Kenyan runner (d. 2003)
1945 – Steve Spurrier, American football player and head coach, 1966 Heisman Trophy winner
1946 – Sandro Chia, Italian painter and sculptor
1946 – Julien Poulin, Canadian actor, director, producer, and screenwriter
1946 – Gordon Smiley, American race car driver (d. 1982)
1947 – Rita Dionne-Marsolais, Canadian economist and politician
1947 – David Leland, English actor, director, and screenwriter
1947 – Viktor Suvorov, Russian intelligence officer, historian, and author
1948 – Gregory Itzin, American actor
1948 – Matthias Kuhle, German geographer and academic (d. 2015)
