Eventos el May 20 50
Año 325
The First Council of Nicaea is formally opened, starting the first ecumenical council of the Christian Church.
Año 491
Empress Ariadne marries Anastasius I. The widowed Augusta is able to choose her successor for the Byzantine throne, after Zeno (late emperor) dies of dysentery.
Año 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.
Año 794
King Æthelberht II of East Anglia visits the royal Mercian court at Sutton Walls, with a view to marrying princess Ælfthryth. He is taken captive and beheaded.
Año 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.
Año 1293
King Sancho IV of Castile creates the Estudio de Escuelas de Generales in Alcalá de Henares.
Año 1449
The Battle of Alfarrobeira is fought, establishing the House of Braganza as a principal royal family of Portugal.
Año 1497
John Cabot sets sail from Bristol, England, on his ship Matthew looking for a route to the west (other documents give a May 2 date).
Año 1498
Portuguese explorer Vasco da Gama discovers the sea route to India when he arrives at Kozhikode (previously known as Calicut), India.
Año 1520
The massacre at the festival of Tóxcatl takes place during the Fall of Tenochtitlan, resulting in turning the Aztecs against the Spanish.
Año 1570
Cartographer Abraham Ortelius issues Theatrum Orbis Terrarum, the first modern atlas.
Año 1609
Shakespeare's sonnets are first published in London, perhaps illicitly, by the publisher Thomas Thorpe.
Año 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.
Año 1645
Yangzhou massacre: the 10-day massacre of 800,000 residents of the city of Yangzhou, part of the Transition from Ming to Qing.
Año 1775
The controversial Mecklenburg Declaration of Independence is allegedly signed in Charlotte, North Carolina.
Año 1802
By the Law of 20 May 1802, Napoleon Bonaparte reinstates slavery in the French colonies, revoking its abolition in the French Revolution.
Año 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.
Año 1861
American Civil War: The state of Kentucky proclaims its neutrality, which will last until September 3 when Confederate forces enter the state. Meanwhile, the State of North Carolina secedes from the Union.
Año 1864
American Civil War: Battle of Ware Bottom Church: In the Virginia Bermuda Hundred Campaign, 10,000 troops fight in this Confederate victory.
Año 1873
Levi Strauss and Jacob Davis receive a U.S. patent for blue jeans with copper rivets.
Año 1875
Signing of the Metre Convention by 17 nations leading to the establishment of the International System of Units.
Año 1882
The Triple Alliance between the German Empire, Austria-Hungary and the Kingdom of Italy is formed.
Año 1883
Krakatoa begins to erupt; the volcano explodes three months later, killing more than 36,000 people.
Año 1891
History of cinema: The first public display of Thomas Edison's prototype kinetoscope.
Año 1902
Cuba gains independence from the United States. Tomás Estrada Palma becomes the country's first President.
Año 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.
Año 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.
Año 1940
The Holocaust: The first prisoners arrive at a new concentration camp at Auschwitz.
Año 1949
In the United States, the Armed Forces Security Agency, the predecessor to the National Security Agency, is established.
Año 1956
In Operation Redwing, the first United States airborne hydrogen bomb is dropped over Bikini Atoll in the Pacific Ocean.
Año 1964
Discovery of the cosmic microwave background radiation by Robert Woodrow Wilson and Arno Penzias.
Año 1967
The Popular Movement of the Revolution political party is established in the Democratic Republic of the Congo.
Año 1971
In the Chuknagar massacre, Pakistani forces massacre thousands, mostly Bengali Hindus.
Año 1980
In a referendum in Quebec, the population rejects, by 60% of the vote, a government proposal to move towards independence from Canada.
Año 1983
First publications of the discovery of the HIV virus that causes AIDS in the journal Science by Luc Montagnier.
Año 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.
Año 1989
The Chinese authorities declare martial law in the face of pro-democracy demonstrations, setting the scene for the Tiananmen Square massacre.
Año 1990
The first post-Communist presidential and parliamentary elections are held in Romania.
Año 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.
Año 2002
The independence of East Timor is recognized by Portugal, formally ending 23 years of Indonesian rule and three years of provisional UN administration (Portugal itself is the former colonizer of East Timor until 1976).
Año 2012
At least 27 people are killed and 50 others injured when a 6.0-magnitude earthquake strikes northern Italy.
Año 2013
An EF5 tornado strikes the Oklahoma City suburb of Moore, killing 24 people and injuring 377 others.