WHAT HAPPENED ON 20. APRIL
Want to find out what all happened on 20. April

Astronomer Pietro Angelo Secchi demonstrates the Secchi disk, which measures water clarity, aboard Pope Pius IX's yacht, the L'Immaculata Concezion. (20. April 1865)

The Civil Rights Act of 1871 becomes law. (20. April 1871)

The April Uprising, a key point in modern Bulgarian history, leading to the Russo-Turkish War and the liberation of Bulgaria from domination as an independent part of the Ottoman Empire. (20. April 1876)

Pope Leo XIII publishes the encyclical Humanum Genus. (20. April 1884)

Pierre and Marie Curie refine radium chloride. (20. April 1902)

Opening day of competition in the New South Wales Rugby League. (20. April 1908)

Opening day for baseball's Tiger Stadium in Detroit, Michigan, and Fenway Park in Boston. (20. April 1912)

19 men, women, and children die in the Ludlow Massacre during a Colorado coal-miner's strike. (20. April 1914)

The Chicago Cubs play their first game at Weeghman Park (currently Wrigley Field), defeating the Cincinnati Reds 7-6 in 11 innings. (20. April 1916)

Manfred von Richthofen, aka The Red Baron, shoots down his 79th and 80th victims, his final victories before his death the following day. (20. April 1918)

The Soviet government creates South Ossetian Autonomous Oblast within Georgian SSR. (20. April 1922)

Western Electric and Warner Bros. announce Vitaphone, a process to add sound to film. (20. April 1926)

Adolf Hitler's 50th birthday is celebrated as a national holiday in Nazi Germany. (20. April 1939)

Billie Holiday records the first civil rights song "Strange Fruit". (20. April 1939)

World War II: US troops capture Leipzig, Germany, only to later cede the city to the Soviet Union. (20. April 1945)

World War II: Führerbunker: Adolf Hitler makes his last trip to the surface to award Iron Crosses to boy soldiers of the Hitler Youth. (20. April 1945)

The League of Nations officially dissolves, giving most of its power to the United Nations. (20. April 1946)

Dan Gavriliu performs the first surgical replacement of a human organ. (20. April 1951)

Failure of the Bay of Pigs Invasion of US-backed Cuban exiles against Cuba. (20. April 1961)

BBC Two launches with a power cut because of the fire at Battersea Power Station. (20. April 1964)