Browse Historical Events by Day: What Happened on April 20th?

The Irish Viking fleet is defeated by the Franks at the Battle of Leuven in present-day Belgium.

Henry III, also known as Henry the Black is crowned King of Germany in the Cathedral of Aachen by Pilgrim, Archbishop of Cologne. Upon the death of his father on 4 June 1039 he became sole ruler of the kingdom and was crowned Holy Roman Emperor by Pope Clement II in Rome in 1046. More

Construction begins on the Campanile (Leaning Tower of Pisa).

Siege of Acre: Crusaders under King Richard I capture Acre from the Muslims after a prolonged siege.

Pope Clement V succeeds Pope Benedict XI, becoming the 195th pope.

Dutch sailor Jan van Riebeeck establishes a settlement at Cape Town, South Africa.

Oliver Cromwell dissolves the Rump Parliament in England, leading to the rule of the Protectorate.

France declares war on Austria, marking the start of the French Revolutionary Wars.

The United Irishmen Rebellion against British rule in Ireland begins with a failed uprising.

The American Society for the Prevention of Cruelty to Animals (ASPCA) is founded in New York City.

The Civil Rights Act of 1871, also known as the Ku Klux Klan Act, is enacted in the United States. More

German scientist Robert Koch identifies the tubercle bacillus responsible for tuberculosis. He also determined how the disease spread, primarily through bodily fluids, like sputum. For this work, he was awarded the Nobel Prize in Physiology or Medicine in 1905. More

The U.S. Supreme Court decision in Swann v. Charlotte-Mecklenburg Board of Education unanimously rules that busing could be used as a tool to achieve racial integration in schools. This decision authorized judges to mandate busing to address racial imbalance in education. More

Korean Air Lines jet Flight 902 (KAL 902), on a flight from Paris to Seoul, is forced down over the Soviet Union after the jet veers into Russian airspace. What happened next is not exactly clear. It may have been a missile fired by the fighters, or it may have been their guns. But the result was a major portion of the airline jet left wing was destroyed and the fuselage was punctured, causing immediate decompression of the cabin. Two of the passengers died and several others were injured. The jet managed to dive into the clouds and evade the Russian jets and it eventually made a rough landing on a frozen lake bout 300 miles south of Murmansk. More

Fidel Castro announces that all Cubans wanting to leave the island could do so, as long as they left from Mariel Harbor, a port 25 miles west of the capital of Havana, and had someone waiting to retrieve them More

The Columbine High School massacre occurs in Colorado, resulting in the deaths of 15 individuals, including the perpetrators.

An explosion on the Deepwater Horizon oil rig in the Gulf of Mexico kills 11 people and leads to a massive oil spill. Days after the April 20, 2010 explosion and sinking of the Deepwater Horizon oil rig in the Gulf of Mexico, underwater cameras revealed the damaged wellhead pipe was leaking oil and gas on the ocean floor about 42 miles off the coast of Louisiana. By the time the well was capped 87 days later on July 15, 2010, an estimated 3.19 million barrels of oil had leaked into the Gulf. More

Derek Chauvin, a former Minneapolis police officer, is found guilty of murdering George Floyd, sparking global conversations about racial justice and police brutality.