In History, Today on April 20

Cuba's National Assembly elected Miguel Díaz-Canel as the new President, marking the end of the Castro era in Cuban leadership.

The Chinese government permitted a Duke of Cambridge visit, marking a significant moment in UK-China diplomatic relations.

A 6.6 magnitude earthquake struck Lushan County in Sichuan, China, resulting in significant casualties and damage.

The Deepwater Horizon oil rig exploded in the Gulf of Mexico, leading to one of the largest environmental disasters in U.S. history.

Danica Patrick became the first woman to win an IndyCar race, achieving victory at the Indy Japan 300.

President of Estonia, Toomas Hendrik Ilves, officially broke ground on the new building for the Estonian National Museum.

Australia's Macquarie Island, a UNESCO World Heritage site, was formally added to the UNESCO World Heritage List.

The Columbine High School massacre occurs in Littleton, Colorado, where two students open fire, killing 13 people and wounding more than 20 others before committing suicide.

Pierre Elliott Trudeau is sworn in as the 15th Prime Minister of Canada, marking the beginning of his first term in office.

The Bay of Pigs Invasion ends in failure for the United States. The CIA-backed Cuban exiles are defeated by Fidel Castro's forces, strengthening his regime.

The League of Nations officially dissolved, transferring most of its functions to the newly established United Nations.

During World War II, Adolf Hitler makes his last trip to the surface from his underground bunker to award Iron Crosses to Hitler Youth members.

The Ludlow Massacre occurs in Colorado, where striking coal miners and their families are attacked by the Colorado National Guard and company guards, resulting in numerous deaths.

Adolf Hitler is born in Braunau am Inn, Austria. He would later become the dictator of Nazi Germany, leading the country during World War II and orchestrating the Holocaust.

Pope Leo XIII published the encyclical Humanum genus, which denounced Freemasonry and reiterated the Catholic Church's opposition to it.

The Third Carlist War began in Spain, a movement by Catholic regent Carlos, Duke of Madrid to claim the Spanish throne.

The U.S. Congress established the Territory of Wisconsin, which was then composed of the area between Lake Michigan and the Mississippi River and north of the state of Illinois. This began the process of organizing the area into what would become the state of Wisconsin in 1848.

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

The Siege of Boston begins during the American Revolutionary War, following the battles of Lexington and Concord.

Captain James Cook arrives in Australia, marking the first European contact with the eastern coastline of the continent.

The Treaty of Paris is signed, ending the Anglo-Spanish War (1654–1660) between France and Spain.

Oliver Cromwell dissolves the Rump Parliament by force, marking a significant moment in the English Interregnum.

Jacques Cartier sets sail on his first voyage to the New World, commissioned by King Francis I of France to explore the northern lands, which would later become Canada.

The Sapienza University of Rome was founded by Pope Boniface VIII, becoming one of the world's oldest and most prestigious educational institutions.

King Richard I of England returned to England from his captivity in Germany. Richard had been held in captivity by Holy Roman Emperor Henry VI since December 1192 following his return from the Third Crusade and was released after a hefty ransom was paid.

The Second Lateran Council, convened by Pope Innocent II, concluded in Rome. This council addressed various church reforms, reconfirmed the illegitimacy of the antipopes, and specifically condemned clerical marriage, concubinage, and the ordination of sons of priests.

The Synod of Paris, a significant ecclesiastical council, was held to address issues within the Frankish church.

According to Islamic tradition, the Prophet Muhammad was born in Mecca on this date, although the exact date is debated among historians.