1971: The U.S. Government forcibly removes the last holdouts to the Native American Occupation of Alcatraz, ending 19 months of control.
1970: After being appointed on May 15, Anna Mae Hays and Elizabeth P. Hoisington officially receive their ranks as U.S. Army Generals, becoming the first females to do so.
1968: Lloyd J. Old identified the first cell surface antigens that could differentiate among different cell types.
1964: World War II veteran Walter Seifert runs amok in an elementary school in Cologne, Germany, killing at least eight children and two teachers and seriously injuring several more with a home-made flamethrower and a lance.
1963: John F. Kennedy addresses Americans from the Oval Office proposing the Civil Rights Act of 1964, which would revolutionize American society by guaranteeing equal access to public facilities, ending segregation in education, and guaranteeing federal protection for voting rights.
1963: Buddhist monk Thích Quảng Đức burns himself with gasoline in a busy Saigon intersection to protest the lack of religious freedom in South Vietnam.
1962: Frank Morris, John Anglin and Clarence Anglin allegedly become the only prisoners to escape from the prison on Alcatraz Island.
1956: Start of Gal Oya riots, the first reported ethnic riots that target minority Sri Lankan Tamils in the Eastern Province. The total number of deaths is reportedly 150.
1955: Eighty-three spectators are killed and at least 100 are injured after an Austin-Healey and a Mercedes-Benz collide at the 24 Hours of Le Mans, the deadliest ever accident in motorsports.
1920: During the U.S. Republican National Convention in Chicago, U.S. Republican Party leaders gathered in a room at the Blackstone Hotel to come to a consensus on their candidate for the U.S. presidential election, leading the Associated Press to coin the political phrase "smoke-filled room".
1919: Sir Barton wins the Belmont Stakes, becoming the first horse to win the U.S. Triple Crown.
1917: King Alexander assumes the throne of Greece after his father, Constantine I, abdicates under pressure from allied armies occupying Athens.
1903: A group of Serbian officers stormed the royal palace and assassinated King Alexander Obrenović and his wife, Queen Draga.
1748: Denmark adopts the characteristic Nordic Cross flag later taken up by all other Scandinavian countries.
1594: Philip II recognizes the rights and privileges of the local nobles and chieftains in the Philippines, which paved way to the stabilization of the rule of the Principalía (an elite ruling class of native nobility in Spanish Philippines).
631: Emperor Taizong of Tang, the Emperor of China, sends envoys to the Xueyantuo bearing gold and silk in order to seek the release of enslaved Chinese prisoners captured during the transition from Sui to Tang from the northern frontier; this embassy succeeded in freeing 80,000 Chinese men and women who were then returned to China.
173: Marcomannic Wars: The Roman army in Moravia is encircled by the Quadi, who have broken the peace treaty (171). In a violent thunderstorm emperor Marcus Aurelius defeats and subdues them in the so-called "miracle of the rain".