305 - Diocletian and Maximian retire from the office of Roman Emperor.
1045 - Gregory VI is appointed Pope.
1328 - Wars of Scottish Independence end: Treaty of Edinburgh-Northampton – England recognises Scotland as an independent nation.
1396 - The Dahu becomes Switzerland's national animal.
1576 - Stefan Batory, the reigning Prince of Transylvania, marries Anna Jagiellon and they become the co-rulers of the Polish-Lithuanian Commonwealth.
1707 - The Act of Union joins England and Scotland to form the Kingdom of Great Britain.
1751 - The first cricket match is played in America.
1753 - Publication of Species Plantarum by Linnaeus, and the formal start date of plant taxonomy adopted by the International Code of Botanical Nomenclature.
1778 - American Revolution: The Battle of Crooked Billet begins in Hatboro, Pennsylvania.
1786 - Opening night of the opera The Marriage of Figaro by Wolfgang Amadeus Mozart in Vienna.
1834 - The British colonies abolish slavery.
1851 - The Great Exhibition is opened in London by Queen Victoria.
1863 - American Civil War: The Battle of Chancellorsville begins.
1869 - The Folies Bergères open in Paris.
1884 - Proclamation of the demand for eight-hour workday in the United States
1886 - The start of the general strike which eventually wins the eight-hour workday in the United States. These events are today commemorated as May Day or Labor Day in most industrialized countries.
1893 - The World's Columbian Exposition opens in Chicago.
1894 - Coxey's Army, the first significant American protest march, arrives in Washington D.C..
1898 - Spanish-American War: The Battle of Manila Bay - The United States Navy destroys the Spanish Pacific fleet in the first battle of the war.
1900 - The Scofield mine disaster kills 200 in Scofield, Utah in the now fifth-worst mining accident in United States history.
1901 - The Pan-American Exposition opens in Buffalo, New York.
1915 - RMS Lusitania departs New York City on her two hundred and second and final crossing of the North Atlantic. Six days later the ship was torpedoed off the Irish coast with the loss of 1,198 lives, including 128 Americans, rousing American sentiment against Germany.
1925 - The All-China Federation of Trade Unions is officially founded. Today it is the largest trade union in the world, with 134 million members.
1927 - The first cooked meals on a scheduled flight are introduced on an Imperial Airways flight from London to Paris.
1927 - The Union Labor Life Insurance Company is founded by the American Federation of Labor.
1930 - The dwarf planet Pluto is officially named.
1931 - The Empire State Building is dedicated in New York City.
1940 - The 1940 Summer Olympics are cancelled due to war.
1941 - Orson Welles's Citizen Kane premieres in New York City
1941 - World War II: German forces launch Operation Mercury the largest airborne invasion to date in their bid to capture Crete.
1941 - World War II: German forces launch a major attack on Tobruk.
1945 - Soviet troops raise the Soviet Flag over the Reichstag, in Berlin
1945 - A German newsreader officially announces that Adolf Hitler had "fallen at his command post in the Reich Chancellery fighting to the last breath against Bolshevism and for Germany".
1946 - Start of 3 year Pilbara strike of Indigenous Australians.
1946 - The Paris Peace Conference desides that the islands of the Dodecanese are returned to Greece by the Italians.
1948 - The Democratic People's Republic of Korea (North Korea) is established, with Kim Il Sung as president.
1950 - Guam is organized as a United States commonwealth.
1956 - The polio vaccine developed by Jonas Salk is made available to the public.
1956 - A doctor in Japan reports an "epidemic of an unknown disease of the central nervous system", marking the official discovery of Minamata disease
1960 - Cold War: U-2 Crisis – Francis Gary Powers, in a Lockheed U-2 spyplane, is shot down over the Soviet Union, sparking off a diplomatic crisis.
1961 - The Prime minister of Cuba, Fidel Castro, proclaimes Cuba a socialist nation and abolishes elections.
1965 - Battle of Dong-Yin, a naval conflict between ROC and PRC.
1967 - Singer Elvis Presley marries Priscilla Beaulieu in Las Vegas.
1970 - Protests erupt in Seattle, Washington, United States following the announcement of President Richard M. Nixon (1913-1994) that U.S. Forces in Vietnam would pursue enemy troops into Cambodia, a neutral country. [1]
1971 - Amtrak (the National Railroad Passenger Corporation) is formed to take over U.S. passenger rail service.
1978 - Japan's Naomi Uemura, travelling by dog sled, becomes the first person to reach the North Pole alone.
1978 - The first unsolicited bulk commercial e-mail (which would later become known as "spam") was sent by a DEC marketing representative to every ARPANET address on the west coast of the United States.
1978 - May Day Bank Holiday introduced across England.
1982 - The 1982 World's Fair opens in Knoxville, Tennessee.
1983 - Greek composer Mikis Theodorakis is awarded the Lenin Peace Prize.
1987 - Pope John Paul II beatifies Edith Stein, a Jewish-born Carmelite nun who was gassed in the Nazi concentration camp at Auschwitz.
1989 - The coat of arms of Greenland is adopted.
1989 - Disney-MGM studios opens in Orlando, Florida.
To be continued....

1931 - The Empire State Building is dedicated in New York City. Now that's an event makes Americans  proud.
1971 - Amtrak (the National Railroad Passenger Corporation) is formed to take over U.S. passenger rail service.(Important event for train fans )
1978 - Japan's Naomi Uemura, travelling by dog sled, becomes the first person to reach the North Pole alone. That must be hard.