On this day: 31 March

After divorcing his wife Minervina, Constantine marries Fausta, daughter of the retired Roman emperor Maximian.

French abbot Bernard of Clairvaux preached a sermon to a crowd at a council in Vézelay, with King Louis VII in attendance, urging the necessity of a Second Crusade.

A conspiracy against Saladin, aiming to restore the Fatimid Caliphate, was revealed in Cairo.

Pope Gregory X calls for a General Church Council to discuss reunion of Churches, Crusade to the Holy Land and Church reform.

Ferdinand Magellan and members of his crew participated in the first Catholic Mass in the Philippines.

The last session of history of the Catalan Courts, the parliament of the Principality of Catalonia, ends. Catalonia's constitutional modernisation passed by the Courts aims to improve the guarantee of individual, political and economic rights (such as the secrecy of correspondence).

The Sixth Coalition occupies Paris after Napoleon's Grande Armée capitulates.

U.S. Navy Commodore Matthew C. Perry (Japanese depiction pictured) and the Tokugawa shogunate signed the Convention of Kanagawa, forcing the opening of Japanese ports to American trade.

The Eiffel Tower is officially opened.

Philippine–American War: Malolos, capital of the First Philippine Republic, was captured by American forces.

A magnitude 7.2 earthquake struck the Black Sea, the most powerful ever recorded in the area.

Rusalka by Antonín Dvořák premieres at the National Opera House in Prague.

Kaiser Wilhelm II of Germany declares his support for Moroccan independence in Tangier, beginning the First Moroccan Crisis.

The Intercollegiate Athletic Association of the United States (later the National Collegiate Athletic Association) is established to set rules for college sports in the United States.

Serbia formally withdraws its opposition to Austro-Hungarian actions in the Bosnian Crisis.

According to the terms of the Treaty of the Danish West Indies, the islands become American possessions.

Daylight saving time goes into effect in the United States for the first time.

The Australian Air Force was formed, replacing the short-lived Australian Air Corps and separating it from the Army.

To avoid government censorship, Hollywood movie studios instituted their own set of industry censorship guidelines, popularly known as the Hays Code.

The Civilian Conservation Corps is established with the mission of relieving rampant unemployment in the United States.

World War II: A defecting German pilot delivers a Messerschmitt Me 262A-1, the world's first operational jet-powered fighter aircraft, to the Americans, the first to fall into Allied hands.

Remington Rand delivers the first UNIVAC I computer to the United States Census Bureau.

Elections to the Territorial Assembly of the French colony Upper Volta are held. After the elections PDU and MDV form a government.

In the Canadian federal election, the Progressive Conservatives, led by John Diefenbaker, win the largest percentage of seats in Canadian history, with 208 seats of 265.

After a two-week escape journey from Tibet, the 14th Dalai Lama reached the Tawang Monastery in Arunachal Pradesh in India.

The Brazilian Armed Forces overthrew President João Goulart, establishing a military dictatorship that lasted 21 years.

The Soviet Union launches Luna 10 which later becomes the first space probe to enter orbit around the Moon.

American President Lyndon B. Johnson speaks to the nation of "Steps to Limit the War in Vietnam" in a television address. At the conclusion of his speech, he announces: "I shall not seek, and I will not accept, the nomination of my party for another term as your President."

Explorer 1 re-enters the Earth's atmosphere after 12 years in orbit.

The Chicago, Rock Island and Pacific Railroad operates its final train after being ordered to liquidate its assets because of bankruptcy and debts owed to creditors.

The Warsaw Pact formally disbands.

Georgian independence referendum: Nearly 99 percent of the voters support the country's independence from the Soviet Union.

USS Missouri, the last active United States Navy battleship, was decommissioned in Long Beach, California.

The Treaty of Federation is signed in Moscow.

The Macao Basic Law is adopted by the Eighth National People's Congress of China to take effect December 20, 1999. Resumption by China of the Exercise of Sovereignty over Macao

Netscape releases Mozilla source code under an open source license.

The Old National Library Building in Singapore was closed to make way for a tunnel, despite widespread protests.

The dwarf planet Makemake is discovered by a team led by astronomer Michael E. Brown at the Palomar Observatory.

NASA astronaut Scott Kelly and Roscosmos cosmonaut Mikhail Kornienko return to Earth after a yearlong mission at the International Space Station.

Nikol Pashinyan began his protest walk, starting in the city of Gyumri, opening the 2018 Armenian revolution.

A historic tornado outbreak occurs in the American Midwest and South.