May 20
Events
Pre-1600
- 325 - The First Council of Nicaea is formally opened, starting the first ecumenical council of the Christian Church.
- 491 - Empress Ariadne marries Anastasius I. The widowed Augusta is able to choose her successor for the Byzantine throne, after Zeno dies of dysentery.
- 685 - The Battle of Dun Nechtain is fought between a Pictish army under King Bridei III and the invading Northumbrians under King Ecgfrith, who are decisively defeated.
- 794 - While visiting the royal Mercian court at Sutton Walls with a view to marrying princess Ælfthryth, King Æthelberht II of East Anglia is taken captive and beheaded.
- 1217 - The Second Battle of Lincoln is fought near Lincoln, England, resulting in the defeat of Prince Louis of France by William Marshal, 1st Earl of Pembroke.
- 1293 - King Sancho IV of Castile creates the Estudio de Escuelas de Generales in Alcalá de Henares.
- 1426 - King Mohnyin Thado formally ascends to the throne of Ava.
- 1449 - The Battle of Alfarrobeira is fought, establishing the House of Braganza as a principal royal family of Portugal.
- 1497 - John Cabot sets sail from Bristol, England, on his ship looking for a route to the west.
- 1498 - Portuguese explorer Vasco da Gama discovers the sea route to India when he arrives at Kozhikode, India.
- 1520 - Hernan Cortés defeats Pánfilo de Narváez, sent by Spain to punish him for insubordination.
- 1521 - Ignatius of Loyola is seriously wounded in the Battle of Pampeluna.
- 1570 - Cartographer Abraham Ortelius issues Theatrum Orbis Terrarum, the first modern atlas.
1601–1900
- 1609 - Shakespeare's sonnets are first published in London, perhaps illicitly, by the publisher Thomas Thorpe.
- 1631 - The city of Magdeburg in Germany is seized by forces of the Holy Roman Empire and most of its inhabitants massacred, in one of the bloodiest incidents of the Thirty Years' War.
- 1645 - Yangzhou massacre: The ten day massacre of the residents of the city of Yangzhou, part of the Transition from Ming to Qing.
- 1714 - Johann Sebastian Bach leads the first performance of his cantata for Pentecost, Erschallet, ihr Lieder, BWV 172, at the chapel of Schloss Weimar.
- 1741 - The Battle of Cartagena de Indias ends in a Spanish victory and the British begin withdrawal towards Jamaica with substantial losses.
- 1775 - The Mecklenburg Declaration of Independence is allegedly signed in Charlotte, North Carolina.
- 1802 - By the Law of 20 May 1802, Napoleon Bonaparte reinstates slavery in the French colonies, revoking its abolition in the French Revolution.
- 1813 - Napoleon Bonaparte leads his French troops into the Battle of Bautzen in Saxony, Germany, against the combined armies of Russia and Prussia. The battle ends the next day with a French victory.
- 1861 - American Civil War: The state of Kentucky proclaims its neutrality, which will last until September 3 when Confederate forces enter the state.
- 1861 - American Civil War: The State of North Carolina secedes from the Union.
- 1862 - U.S. President Abraham Lincoln signs the Homestead Act into law, opening of public land to settlers.
- 1864 - American Civil War: Battle of Ware Bottom Church: In the Virginia Bermuda Hundred campaign, 10,000 troops fight in this Confederate victory.
- 1873 - Levi Strauss and Jacob Davis receive a U.S. patent for blue jeans with copper rivets.
- 1875 - Signing of the Metre Convention by 17 nations leading to the establishment of the International System of Units.
- 1882 - The Triple Alliance between the German Empire, Austria-Hungary and the Kingdom of Italy is formed.
- 1883 - Krakatoa begins to erupt; the volcano explodes three months later, killing more than 36,000 people.
- 1891 - History of cinema: The first public display of Thomas Edison's prototype kinetoscope.
1901–present
- 1902 - Cuba gains independence from the United States. Tomás Estrada Palma becomes the country's first President.
- 1927 - Treaty of Jeddah: The United Kingdom recognizes the sovereignty of King Ibn Saud in the Kingdoms of Hejaz and Nejd, which later merge to become the Kingdom of Saudi Arabia.
- 1927 - Charles Lindbergh takes off for Paris from Roosevelt Field in Long Island, N.Y., aboard the Spirit of St. Louis on the first nonstop solo flight across the Atlantic Ocean, landing hours later.
- 1932 - Amelia Earhart takes off from Newfoundland to begin the world's first solo nonstop flight across the Atlantic Ocean by a female pilot, landing in Ireland the next day.
- 1940 - The Holocaust: The first prisoners arrive at a new concentration camp at Auschwitz.
- 1941 - World War II: Battle of Crete: German paratroops invade Crete.
- 1943 - The Luttra Woman, a bog body from the Early Neolithic period, was discovered near Luttra, Sweden.
- 1948 - Generalissimo Chiang Kai-shek wins the 1948 Republic of China presidential election and is sworn in as the first President of the Republic of China at Nanjing.
- 1949 - In the United States, the Armed Forces Security Agency, the predecessor to the National Security Agency, is established.
- 1956 - In Operation Redwing, the first United States airborne hydrogen bomb is dropped over Bikini Atoll in the Pacific Ocean.
- 1958 - Capital Airlines Flight 300 collides in mid-air with a United States Air Force Lockheed T-33 over Brunswick, Maryland, killing 12.
- 1964 - Discovery of the cosmic microwave background radiation by Robert Woodrow Wilson and Arno Penzias.
- 1965 - One hundred twenty-one people are killed when Pakistan International Airlines Flight 705 crashes at Cairo International Airport.
- 1967 - The Popular Movement of the Revolution political party is established in the Democratic Republic of the Congo.
- 1969 - The Battle of Hamburger Hill in Vietnam ends.
- 1971 - In the Chuknagar massacre, Pakistani forces massacre thousands, mostly Bengali Hindus.
- 1980 - In a referendum in Quebec, the population rejects, with 60% of the vote, a government proposal to move towards independence from Canada.
- 1983 - First publications of the discovery of the HIV virus that causes AIDS in the journal Science by a team of French scientists including Françoise Barré-Sinoussi, Jean-Claude Chermann, and Luc Montagnier.
- 1983 - Church Street bombing: A car bomb planted by UMkhonto we Sizwe explodes on Church Street in South Africa's capital, Pretoria, killing 19 people and injuring 217 others.
- 1985 - Radio Martí, part of the Voice of America service, begins broadcasting to Cuba.
- 1989 - The Chinese authorities declare martial law in the face of pro-democracy demonstrations, setting the scene for the Tiananmen Square massacre.
- 1990 - The first post-Communist presidential and parliamentary elections are held in Romania.
- 1996 - Civil rights: The Supreme Court of the United States rules in Romer v. Evans against a law that would have prevented any city, town or county in the state of Colorado from taking any legislative, executive, or judicial action to protect the rights of gays and lesbians.
- 2002 - The independence of East Timor is recognized by Portugal, formally ending 23 years of Indonesian rule and three years of provisional UN administration.
- 2009 - An Indonesian Air Force Lockheed L-100 Hercules crashes in Magetan Regency, killing 99.
- 2011 - Mamata Banerjee is sworn in as the Chief Minister of West Bengal, the first woman to hold this post.
- 2012 - At least 27 people are killed and 50 others injured when a 6.0-magnitude earthquake strikes northern Italy.
- 2013 - An EF5 tornado strikes the Oklahoma City suburb of Moore, killing 24 people and injuring 377 others.
- 2016 - The government of Singapore authorised the controversial execution of convicted murderer Kho Jabing for the murder of a Chinese construction worker despite the international pleas for clemency, notably from Amnesty International and the United Nations.
- 2019 - The International System of Units : The base units are redefined, making the international prototype of the kilogram obsolete.
- 2022 - Russo-Ukrainian War: Russia claims full control of the Ukrainian city of Mariupol after a nearly three-month siege.
Births
Pre-1600
- 1315 - Bonne of Luxembourg, first wife of John II of France
- 1470 - Pietro Bembo, Italian cardinal, poet, and scholar
- 1505 - Levinus Lemnius, Dutch writer
- 1531 - Thado Minsaw of Ava, Viceroy of Ava
- 1537 - Hieronymus Fabricius, Italian anatomist
- 1575 - Robert Heath, English judge and politician
1601–1900
- 1664 - Andreas Schlüter, German sculptor and architect
- 1726 - Francis Cotes, English painter and academic
- 1759 - William Thornton, Virgin Islander-American architect, designed the United States Capitol
- 1769 - Andreas Vokos Miaoulis, Greek admiral and politician
- 1772 - Sir William Congreve, 2nd Baronet, English inventor and politician, developed Congreve rockets
- 1776 - Simon Fraser, American-Canadian fur trader and explorer
- 1795 - Pedro María de Anaya, Mexican soldier. President
- 1799 - Honoré de Balzac, French novelist and playwright
- 1806 - John Stuart Mill, English economist, civil servant, and philosopher
- 1811 - Alfred Domett, English-New Zealand poet and politician, 4th Prime Minister of New Zealand
- 1818 - William Fargo, American businessman and politician, co-founded Wells Fargo and American Express
- 1822 - Frédéric Passy, French economist and academic, Nobel Prize laureate
- 1824 - Cadmus M. Wilcox, Confederate States Army general
- 1825 - Antoinette Brown Blackwell, the first woman to be ordained as a mainstream Protestant minister in the U.S.
- 1830 - Hector Malot, French author
- 1838 - Jules Méline, French lawyer and politician, 65th Prime Minister of France
- 1851 - Emile Berliner, German-American inventor, invented the Gramophone record
- 1854 - George Prendergast, Australian politician, 28th Premier of Victoria
- 1856 - Henri-Edmond Cross, French Neo-Impressionist painter
- 1860 - Eduard Buchner, German chemist, zymologist, and academic, Nobel Prize laureate
- 1875 - Hendrik Offerhaus, Dutch Olympic rower and head of the Dutch Red Cross
- 1877 - Pat Leahy, Irish-American Olympic jumper
- 1879 - Hans Meerwein, German chemist
- 1882 - Sigrid Undset, Danish-Norwegian novelist, essayist, and translator, Nobel Prize laureate
- 1883 - Faisal I of Iraq
- 1886 - Ali Sami Yen, Turkish footballer and manager, founded the Galatasaray Sports Club
- 1894 - Chandrashekarendra Saraswati, Indian guru and scholar
- 1895 - R. J. Mitchell, English engineer, designed the Supermarine Spitfire and Supermarine S.6B
- 1897 - Diego Abad de Santillán, Spanish economist and author
- 1897 - Malcolm Nokes, English hammer and discus thrower
- 1898 - Eduard Ole, Estonian painter
- 1899 - Aleksandr Deyneka, Russian painter and sculptor
- 1899 - John Marshall Harlan II, American lawyer and jurist, Associate Justice of the US Supreme Court
- 1900 - Sumitranandan Pant, Indian poet and author