May 1: International Workers' Day; Beltane and Samhain in the Northern and Southern Hemispheres, respectively; Maharashtra Day in Maharashtra, India (1960); Loyalty Day in the United States
Moses Fleetwood Walker
- 880 – The Nea Ekklesia church in Constantinople, on which many later cross-in-square Orthodox churches were based, was consecrated.
- 1776 – The secret society known as the Order of Illuminati was founded by Adam Weishaupt and Adolph Freiherr Knigge in Ingolstadt, Bavaria, Germany.
- 1884 – Moses Fleetwood Walker (pictured), the last African American in Major League Baseball until Jackie Robinson, played his first game for the Toledo Blue Stockings.
- 1947 – Sicilian separatist Salvatore Giuliano and his gang fired into a crowd of May Day marchers near Piana degli Albanesi, Sicily, killing 11 and wounding 33.
- 2016 – The evacuation of nearly 88,000 people began when a wildfire swept through Fort McMurray, Alberta, Canada, and burned for another 14 months, becoming the costliest disaster in Canadian history.
May 2: Eid al-Fitr (Islam, 2022); Flag Day in Poland
ARA General Belgrano
May 3: World Press Freedom Day; Constitution Memorial Day in Japan (1947); Onbashira Festival in Nagano, Japan (2022); Constitution Day in Poland (1791)
Scene from Raja Harishchandra
May 4: Youth Day in China; Yom HaZikaron in Israel (2022); Literary Day in Taiwan; Star Wars Day
Parliament House, Valletta
May 5: Lusophone Culture Day; Independence Day in Israel (2022); Children's Day in Japan; Cinco de Mayo in Mexico and the United States (1862); National Day of Prayer in the United States (2022)
Isaac Stern Auditorium, Carnegie Hall
Cartoon of a Chinese man barred from entering the U.S.
May 8: World Red Cross and Red Crescent Day; Anniversary of the birth of Miguel Hidalgo in Mexico (1753); Victory in Europe Day (1945)
The remains of Tollund Man shortly after his discovery
May 9: Europe Day in the European Union; Victory Day in various Eastern European countries (1945); Liberation Day in the Channel Islands (1945)
Battle of Heligoland
Ethan Allen demanding the surrender of Fort Ticonderoga
Julian of Norwich
May 14: Feast day of Saint Matthias (Catholicism)
- 1264 – Second Barons' War: King Henry III was defeated at the Battle of Lewes and forced to sign the Mise of Lewes, making Simon de Montfort the de facto ruler of England.
- 1856 – Major Henry C. Wayne arrived in Indianola, Texas, with 34 camels to form the short-lived United States Camel Corps (pictured).
- 1919 – Sir Harry Hands, the mayor of Cape Town, performed the first public observance of a two-minute silence in remembrance of those killed in World War I.
- 1939 – In Lima, Peru, Lina Medina became the youngest confirmed mother in history, giving birth at the age of five years, seven months and twenty-one days.
- 2008 – On the day of the UEFA Cup Final, violence erupted between football hooligan supporters of both teams and the Greater Manchester Police, resulting in 39 arrests and 39 injured officers.
May 15: Feast day of Saint Carthage (Catholicism); Nakba Day in Palestinian communities
Flag of Sikkim, prior to its 1975 annexation by India
May 17: International Day Against Homophobia, Transphobia and Biphobia; Galician Literature Day in Galicia, Spain
May 18: Haitian Flag Day in Haiti (1803); Day of Remembrance for the Victims of Crimean Tatar Genocide in Ukraine and several other countries
The Bath School after the explosions
- 1302 – Armed insurrectionists massacred the occupying French garrison in Bruges, Flanders, killing approximately 2,000 people.
- 1695 – An earthquake measuring 7.8 struck Shanxi Province in northern China, resulting in at least 52,600 deaths.
- 1927 – Disgruntled school board treasurer Andrew Kehoe set off explosives with timers and a rifle (aftermath pictured), causing the Bath School disaster in the Bath Consolidated School in Michigan, killing 44 people in the deadliest mass murder in a school in United States history.
- 1955 – Operation Passage to Freedom, the evacuation of 310,000 Vietnamese civilians, soldiers and non-Vietnamese members of the French Army from communist North Vietnam to South Vietnam following the end of the First Indochina War, ended.
- 2006 – The Parliament of Nepal unanimously voted to strip King Gyanendra of many of his powers.
May 19: Global Accessibility Awareness Day (2022); Lag BaOmer (Judaism, 2022); Commemoration of Atatürk, Youth and Sports Day in Turkey (1919); Ho Chi Minh's Birthday in Vietnam
Thai soldiers during the crackdown on political protests
May 20: National Day of Remembrance in Cambodia (1976); National Day in Cameroon (1972); National Awakening Day in Indonesia (1908); Sanja Matsuri begins in Tokyo, Japan (2022)
Abdulaziz, also known as Ibn Saud
Charles Lindbergh and the Spirit of St. Louis
May 22: International Day for Biological Diversity
May 23: Aromanian National Day; Victoria Day in Canada (2022)
Joan of Arc
May 24: Aldersgate Day (Methodism)
May 25: Africa Day (1963); Anniversary of the First National Government in Argentina (1810); Independence Day in Jordan (1946)
Great Wall of China
May 26: National Sorry Day in Australia; Independence Day in Georgia (1918)
Artist's impression of the Grue Church fire
Pope Benedict XV
May 28: Republic Day in Armenia (1918); Independence Day in Azerbaijan (1918)
Battle of Jumonville Glen
May 29: Feast day of Saint Paul VI (Catholicism)
May 30: Statehood Day in Croatia (1990); Lod Massacre Remembrance Day in Puerto Rico (1972); Memorial Day in the United States
Statue of Abraham Lincoln in the Lincoln Memorial
- 1854 – The Kansas–Nebraska Act became law, establishing the U.S. territories of Nebraska and Kansas, and allowing their settlers to determine if slavery would be permitted.
- 1866 – Bedřich Smetana's comic opera The Bartered Bride premiered in Prague.
- 1922 – The Lincoln Memorial in Washington, D.C., featuring a sculpture of the sixteenth U.S. president Abraham Lincoln (pictured) by Daniel Chester French, opened.
- 1972 – Members of the Japanese Red Army carried out the Lod Airport massacre in Tel Aviv, Israel, on behalf of PFLP External Operations, killing over 20 people and injuring almost 80 others.
- 2008 – The Convention on Cluster Munitions, prohibiting the use, transfer, and stockpiling of cluster bombs, was adopted.
May 31: World No Tobacco Day; Feast of the Visitation (Catholicism and Anglicanism)