On April 11, 1921, KDKA in Pittsburgh broadcasts the first live sporting event on the radio, a boxing match between Johnny Ray and Johnny Dundee. Pittsburgh Daily Post sports editor Florent Gibson calls the event, about four months before KDKA's Harold Arlin announces the first Major League Baseball game broadcast on radio.

On May 5, 1921, a date of symbolic importance to its iconic creator, the perfume Chanel No. 5 officially debuts in Coco Chanel’s boutique on the Rue Cambon in Paris. The new fragrance immediately revolutionized the perfume industry and remained popular for a century.

Deeply in debt and relegated to a shabby theater, the musical Shuffle Along debuts at the Sixty-Third Street Music Hall on May 23, 1921. The odds are stacked against the revue-style show, written and performed by African Americans, but it will run for over a year, making it the first major Black American musical on the Great White Way.

Beginning on the night of May 31, 1921, thousands of white citizens in Tulsa, Oklahoma descended on the city’s predominantly Black Greenwood District, burning homes and businesses to the ground and killing hundreds of people. Long mischaracterized as a race riot, rather than mass murder, the Tulsa Race Massacre stands as one of the worst incidents of racial violence in the nation’s history.

A paymaster and a security guard are killed during a mid-afternoon armed robbery of a shoe company in South Braintree, Massachusetts. Out of this rather unremarkable crime comes one of the most famous trials in American history: that of Nicola Sacco and Bartolomeo Vanzetti, which began on May 31, 1921.

After Judge Hugo Friend denies a motion to quash the indictments against the major league baseball players accused of throwing the 1919 World Series, a trial begins with jury selection. The Chicago White Sox players, including stars Shoeless Joe Jackson, Buck Weaver and Eddie Cicotte, subsequently became known as the “Black Sox” after the scandal was revealed.

On July 29, 1921, Adolf Hitler becomes the leader of the National Socialist German Workers’ (Nazi) Party. Under Hitler, the Nazi Party grew into a mass movement and ruled Germany as a totalitarian state from 1933 to 1945.

On September 10, 1921, Fatty Arbuckle, a silent-film era performer at the height of his fame, is arrested in San Francisco for the rape and murder of aspiring actress Virginia Rappe. Arbuckle was later acquitted by a jury, but the scandal essentially put an end to his career.

On October 24, 1921, in the French town of Chalons-sur-Marne, an American sergeant selects the body of the first “Unknown Soldier” to be honored among the approximately 77,000 United States servicemen killed on the Western Front during World War I.

Exactly three years after the end of World War I, the Tomb of the Unknown Soldier is dedicated at Arlington Cemetery in Virginia during an Armistice Day ceremony presided over by President Warren G. Harding.

The Irish Free State, comprising four-fifths of Ireland, is declared, ending a five-year Irish struggle for independence from Britain. Like other autonomous nations of the former British Empire, Ireland was to remain part of the British Commonwealth, symbolically subject to the king. The Irish Free State later severed ties with Britain and was renamed Eire, and is now called the Republic of Ireland.