Volcano Eyjafjallajökull erupts in Iceland resulting in massive disruption to air traffic in most of Europe

At least 200,000 demonstrators in Ankara, Turkey protest against the possible candidacy of incumbent Prime Minister Recep Tayyip Erdoğan.

The Oregon Supreme Court nullifies marriage licenses issued to gay couples a year earlier by Multnomah County.

U.S. troops in Baghdad capture Abu Abbas, leader of the Palestinian group that killed an American on the hijacked cruise liner the {{MS|Achille Lauro}} in 1985.

The Human Genome Project is completed with 99% of the human genome sequenced to an accuracy of 99.99%.

Venezuelan President Hugo Chavez returns to office two days after being ousted and arrested by the country's military.

A severe hailstorm strikes Sydney, Australia causing A$2.3 billion in insured damages, the most costly natural disaster in Australian history.

NATO mistakenly bombs a convoy of ethnic Albanian refugees – Yugoslav officials say 75 people are killed.

In a U.S. friendly fire incident during Operation Provide Comfort in northern Iraq, two United States Air Force aircraft mistakenly shoot-down two United States Army helicopters, killing 26 people.

In a United Nations ceremony in Geneva, Switzerland, the Soviet Union signs an agreement pledging to withdraw its troops from Afghanistan.

The {{USS|Samuel B. Roberts|FFG-58|6}} strikes a mine in the Persian Gulf during Operation Earnest Will.

In retaliation for the April 5 bombing in West Berlin that killed two U.S. servicemen, U.S. president Ronald Reagan orders major bombing raids against Libya, killing 60 people.

{{convert|1|kg|lb}} hailstones fall on the Gopalganj district of Bangladesh, killing 92. These are the heaviest hailstones ever recorded.

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1978 Tbilisi Demonstrations: Thousands of Georgians demonstrate against Soviet attempts to change the constitutional status of the Georgian language.

At the U.S. Academy Awards there is a tie for the Academy Award for Best Actress between Katharine Hepburn and Barbra Streisand.

The Soviet satellite Sputnik 2 falls from orbit after a mission duration of 162 days.

In Chicago, Illinois, videotape is first demonstrated.

Osijek, Croatia, is liberated from fascist occupation.

Bombay Explosion: A massive explosion in Bombay harbor kills 300 and causes economic damage valued then at 20 million pounds.

World War II: The Ustashe, a Croatian far-right organization is put in charge of the Independent State of Croatia by the Axis Powers after the Axis Operation 25 invasion. Rommel attacks Tobruk.

World War II: Royal Marines land in Namsos, Norway in preparation for a larger force to arrive two days later.

''The Grapes of Wrath'', by American author John Steinbeck is first published by the Viking Press.

"Black Sunday Storm", the worst dust storm of the U.S. Dust Bowl.

Spanish Cortes depose King Alfonso XIII and proclaims the 2nd Spanish Republic.

The first Volvo car premieres in Gothenburg, Sweden.

The British passenger liner {{RMS|Titanic}} hits an iceberg in the North Atlantic at 11:40pm. The ship sinks the following morning with the loss of 1,517 lives.

The first ever commercial motion picture house opened in New York City using ten Kinetoscopes, a device for peep-show viewing of films.

The Pan-American Union is founded by the First International Conference of American States in Washington, D.C.

The Four Dead in Five Seconds Gunfight is fought in El Paso, Texas.

U.S. Secretary of State William H. Seward and his family are attacked in his home by Lewis Powell.

U.S. President Abraham Lincoln is assassinated in Ford's Theatre by John Wilkes Booth.

Battle of Dybbøl: A Prussian-Austrian army defeats Denmark and gains control of Schleswig. Denmark surrenders the province in the following peace settlement.

The first Pony Express rider reaches Sacramento, California.

Hungary declares itself independent of Austria with Lajos Kossuth as its leader.

The Donner Party of pioneers departs Springfield, Illinois, for California, on what will become a year-long journey of hardship, cannibalism, and survival.

Noah Webster copyrights the first edition of his dictionary.

The first abolition society in North America is established. The Society for the Relief of Free Negroes Unlawfully Held in Bondage is organized in Philadelphia, Pennsylvania by Benjamin Franklin and Benjamin Rush.

Khalsa: Birth of Khalsa, the brotherhood of the Sikh religion, in Northern India in accordance with the Nanakshahi calendar.

In England, the Yorkists under Edward IV defeat the Lancastrians under the Earl of Warwick at the Battle of Barnet; the Earl is killed and Edward IV resumes the throne.

The foundation stone of Cathedral St. Peter and St. Paul in Nantes, France is laid.

Sack of Saluzzo (Italy) by Italian-Angevine troops under Manfred V of Saluzzo.

Temür, grandson of Kublai, is elected Khagan of the Mongols and Emperor of the Yuan Dynasty with the reigning titles Oljeitu and Chengzong.

Battle of Adrianople between Bulgarians and Crusaders.

Henry III, son of Conrad, is elected king of the Germans.

Christianisation of Poland

Siege of Jerusalem: Titus, son of emperor Vespasian, surrounds the Jewish capital, with four Roman legions.

Vitellius, commander of the Rhine armies, defeats Emperor Otho in the Battle of Bedriacum and seizes the throne.