Year 325 » The First Council of Nicea the first Ecumenical Council of the Christian Church is held.
Year 491 » Empress Ariadne (empress) Ariadne marries Anastasius I (emperor) Anastasius I. The widowed 'Augusta (honorific) Augusta' is able to choose her successor for the Byzantine Empire Byzantine throne, after Zeno (emperor) Zeno (late emperor) dies of dysentery.
Year 526 » An 526 Antioch earthquake called earthquake kills about 250,000 people in what is now Syria and Antiochia.
Year 685 » The Battle of Dun Nechtain is fought between a Picts known as Pictish army under King Bridei III and the invading Northumbrians under King Ecgfrith of Northumbria e.g Ecgfrith, who are decisively defeated.
Year 1217 » The Second Battle of Lincoln is fought near Lincoln, Lincolnshire called Lincoln, England, resulting in the defeat of Louis VIII of France known as Prince Louis of France by William Marshal, 1st Earl of Pembroke.
Year 1293 » King Sancho IV of Castile creates the Universidad Complutense de Madrid known as Study of General Schools of Alcalá.
Year 1449 » The Battle of Alfarrobeira is fought, establishing the House of Braganza as a principal royal family of Portugal.
Year 1497 » John Cabot sets sail from Bristol, England, on his ship Ship Matthew ship 6 looking for a route to the west (other documents give a May 2 date).
Year 1498 » Portuguese explorer Vasco da Gama Discovery of the sea route to India known as discovers the sea route to India when he arrives at Kozhikode (previously known as Calicut), India.
Year 1520 » The The massacre in the Main Temple called massacre at the festival of Tóxcatl takes place during the Fall of Tenochtitlan, resulting in turning the Aztecs against the Spanish.
Year 1521 » Ignatius Loyola is seriously wounded in the Battle of Pampeluna.
Year 1570 » Cartography or Cartographer Abraham Ortelius issues 'Theatrum Orbis Terrarum', the first modern atlas.
Year 1775 » Mecklenburg Declaration of Independence is signed in Charlotte, North Carolina or Charlotte, North Carolina
Year 1802 » By the Law of 20 May 1802, Napoleon I of France or Napoleon Bonaparte reinstates slavery in the French colonial empire known as French colonies, revoking its abolition in the French Revolution
Year 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.
Year 1840 » York Minster is badly damaged by fire.
Year 1861 » American Civil War: The state of Kentucky proclaims its neutral country e.g neutrality, which will last until September 3 when Confederate States of America named Confederate forces enter the state. Meanwhile, the State of North Carolina secedes from the
Year 1862 » President of the United States e.g U.S. President Abraham Lincoln signs the Homestead Act into law.
Year 1864 » American Civil War: Battle of Ware Bottom Church in the Virginia Bermuda Hundred Campaign, 10,000 troops fight in this Confederate victory.
Year 1873 » Levi Strauss and Jacob Davis (inventor) called Jacob Davis receive a U.S. patent for blue jeans with copper rivets.
Year 1875 » Signing of the Metre Convention by 17 nations leading to the establishment of the International System of Units.
Year 1882 » The Triple Alliance (1882) named Triple Alliance between the German Empire, Austria-Hungary and the Kingdom of Italy is formed.
Year 1883 » Krakatoa 1883 eruption of Krakatoa e.g begins to erupt; the volcano explodes three months later, killing more than 36,000 people.
Year 1884 » Dinuzulu kaCetshwayo becomes the king of the Zulu Nation.
Year 1896 » The six ton chandelier of the Palais Garnier falls on the crowd below resulting in the death of one and the injury of many others.
Year 1899 » The first traffic ticket in the US: New York City taxi driver Jacob German was arrested for speeding while driving 12 miles per hour on Lexington Street.
Year 1908 » Budi Utomo organization is founded in Dutch East Indies, beginning the Indonesian National Awakening.
Year 1916 » The 'Saturday Evening Post' publishes its first cover with a Norman Rockwell painting ('Boy with Baby Carriage').
Year 1920 » Montreal, Quebec radio station XWA broadcasts the first regularly scheduled radio programming in North America.
Year 1927 » Treaty of Jeddah (1927) named Treaty of Jeddah: the United Kingdom recognizes the sovereignty of King Ibn Saud in the Kingdoms of Hejaz and Najd or Nejd, which later merge to become the Kingdom of Saudi Arabia.
Year 1940 » The Holocaust: The first prisoners arrive at a new concentration camp at Auschwitz.
Year 1941 » World War II: Battle of Crete Nazi Germany called German Fallschirmjäger (World War II) or paratroops invade Crete.
Year 1948 » Chiang Kai-shek is elected as the first President of the Republic of China.
Year 1949 » In the United States, the Armed Forces Security Agency, the predecessor to the National Security Agency, is established.
Year 1956 » In Operation Redwing, the first United States airborne hydrogen bomb is dropped over Bikini Atoll in the Pacific Ocean.
Year 1964 » Discovery of the cosmic microwave background radiation by Robert Woodrow Wilson and Arno Penzias.
Year 1965 » PIA Flight 705, a Pakistan International Airlines Boeing 720 named Boeing 720-040B, crashes while descending to land at Cairo International Airport, killing 121 of the 127 passengers and crew.
Year 1967 » The Popular Movement of the Revolution political party is established in the Democratic Republic of the Congo.
Year 1968 » Operation OAU begins during the Nigerian Civil War
Year 1969 » The Battle of Hamburger Hill in Vietnam ends.
Year 1980 » In a 1980 Quebec referendum named referendum in Quebec, the population rejects by a 60% vote the proposal from its government to move towards independence from Canada.
Year 1983 » First publications of the discovery of the HIV virus that causes AIDS in the journal 'Science (journal) named Science' by Luc Montagnier.
Year 1985 » Radio Martí, part of the Voice of America service, begins broadcasting to Cuba.
Year 1989 » The Chinese authorities declare martial law in the face of pro-democracy demonstrations, setting the scene for the Tiananmen Square massacre.
Year 1990 » The first post-communism named Communist presidential and parliamentary elections are held in Romania.
Year 1996 » LGBT rights in the United States or 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 judicia
Year 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 Portuguese Empire named colonizer of East Timor until 1976).
Year 2006 » 2006 Dhaka strikes called Dhaka wildcat strikes: A series of massive strikes begin, involving nearly 1.8 million garment workers in Bangladesh.
Year 2012 » At least 27 people are killed and 50 others injured when a 2012 Northern Italy earthquakes known as 6.0-magnitude earthquake strikes northern Italy.
Year 2013 » An Enhanced Fujita Scale EF5 2013 Moore tornado tornado strikes the Oklahoma City suburb of Moore, Oklahoma Moore, killing 24 people and injuring 377 others.
Year 2014 » More than 118 people are killed in May 2014 Jos bombings known as two bombings in Jos, Nigeria.