On May 18:
1048 Omar Khayyám, Persian mathematician, poet and philosopher, was born (d. 1131).
1152 Henry II of England married Eleanor of Aquitaine.
1268 The Principality of Antioch, a crusader state, fell to the Mamluk Sultan Baibars in the Battle of Antioch.
1302 Bruges Matins, the nocturnal massacre of the French garrison in Bruges by members of the local Flemish militia.
1498 Vasco da Gama reached the port of Calicut, India.
1593 Playwright Thomas Kyd‘s accusations of heresy led to an arrest warrant for Christopher Marlowe.
1652 Rhode Island passed the first law in North America making slavery illegal.
1765 Fire destroyed a large part of Montreal.
1783 First United Empire Loyalists reached Parrtown, Saint John, New Brunswick, Canada after leaving the United States.
1803 Napoleonic Wars: The United Kingdom revokds the Treaty of Amiens and declared war on France.
1804 Napoleon Bonaparte was proclaimed Emperor of the French by the French Senate.
1811 Battle of Las Piedras: The first great military triumph of the revolution of the Río de la Plata in Uruguay led by Jose Artigas.
1812 John Bellingham was found guilty and sentenced to death by hanging for the assassination of British Prime Minister Spencer Perceval.
1843 The Disruption in Edinburgh of the Free Church of Scotland from the Church of Scotland.
1848 Opening of the first German National Assembly (Nationalversammlung) in Frankfurt.
1860 Abraham Lincoln won the Republican Party nomination over William H. Seward.
1863 American Civil War: The Siege of Vicksburg began.
1828 1868 Nicholas II, Tsar of Russia was born(d. 1918).
1896 The United States Supreme Court ruled in Plessy v. Ferguson that separate but equal is constitutional.
1896 – Khodynka Tragedy: A mass panic on Khodynka Field in Moscow during the festivities of the coronation of Tsar Nicholas II resulted in the deaths of 1,389 people.
1897 Dracula, a novel by Irish author Bram Stoker was published.
1897 Frank Capra, American film producer, director, and writer, was born (d. 1991).
1900 The United Kingdom proclaimed a protectorate over Tonga.
1910 The Earth passed through the tail of Comet Halley.
1912 Perry Como, American singer, was born (d. 2001).
1913 Jane Birdwood, British anti-Semitic activist, was born (d. 2000).
1917 World War I: The Selective Service Act of 1917 was passed, giving the President of the United States the power of conscription.
1919 Dame Margot Fonteyn, English ballet dancer, was born (d. 1991).
1920 Pope John Paul II was born (d. 2005).
1926 Evangelist Aimee Semple McPherson disappeared while visiting a Venice, California beach.
1927 The Bath School Disaster: Forty-five people were killed by bombs planted by a disgruntled school-board member in Michigan.
1933 New Deal: President Franklin D. Roosevelt signed an act creating the Tennessee Valley Authority.
1937 New Zealand nurses René Shadbolt, Isobel Dodds, and Millicent Sharples were detained at Auckland police station before leaving for the Spanish Civil War as recruites for the Spanish Medical Aid COmmittee.
1944 World War II: Battle of Monte Cassino – Conclusion after seven days of the fourth battle as German paratroopers (Fallschirmjäger) evacuated Monte Cassino.
1944 Deportation of Crimean Tatars by the Soviet Union government.
1948 The First Legislative Yuan of the Republic of China officially convened in Nanking.
1949 Rick Wakeman, English composer and musician (Yes) was born.
1949 – Bill Wallace, Canadian musician (The Guess Who) was born.
1953 Jackie Cochran beaome the first woman to break the sound barrier.
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.
1956 First ascent of Lhotse 8,516 metres, by a Swiss team.
1958 An F-104 Starfighter set a world speed record of 2,259.82 km/h (1,404.19 mph).
1959 Launching of the National Liberation Committee of Côte d’Ivoire in Conakry, Guinea.
1966 Koroki Te Rata Mahuta Tawhiao Potatau Te Wherowhero, the fifth Maori monarch heading the Kingitanga movement, died.
1969 Apollo 10 was launched.
1974 Nuclear test: Under project Smiling Buddha, India successfully detonated its first nuclear weapon becoming the sixth nation to do so.
1974 – Completion of the Warsaw radio mast, the tallest construction ever built at the time.
1980 Eruption of Mount St. Helens: killing 57 people and causing $3 billion in damage.
1980 Gwangju Massacre: Students in Gwangju, South Korea began demonstrations, calling for democratic reforms.
1983 In Ireland, the government launched a crackdown, with the leading Dublin pirate Radio Nova put off the air.
1990 In France, a modified TGV train achieved a new rail world speed record of 515.3km/h (320.2 mph).
1991 Northern Somalia declared independence from the rest of Somalia as the Republic of Somaliland but is unrecognised by the international community.
1993 EU-riots in Nørrebro, Copenhagen caused by the approval of the four Danish exceptions in the Maastricht Treaty referendum. Police opened fire against civilians for the first time since World War II and injured 11 demonstrators.
1998 United States v. Microsoft: The United States Department of Justice and 20 U.S. states filed an antitrust case against Microsoft.
2006 The post Loktantra Andolan government passd a landmark bill curtailing the power of the monarchy and making Nepal a secular country.
2009 Sri Lankan Civil War: The LTTE were defeated by the Sri Lankan government, ending almost 26 years of fighting between the two sides.
Sourced from NZ History Online & Wikipedia.