Births on October 21

Ingrid van Houten-Groeneveld, Dutch astronomer and academic (d. 2015)

Ingrid van Houten-Groeneveld (Dutch pronunciation: [ˈɪŋɡrɪt fɑn ˈɦʌutə(ŋ) ˈɣrunəˌvɛlt]; 21 October 1921 – 30 March 2015) was a Dutch astronomer.

15 Feb

Helsinki
Kingdom of Romania establishes its legation in Helsinki.
20 Mar

Versailles Treaty
The Upper Silesia plebiscite was a plebiscite mandated by the Versailles Treaty to determine a section of the border between Weimar Germany and Poland.
11 Jul

William Howard Taft
Former President of the United States William Howard Taft is sworn in as 10th Chief Justice of the U.S. Supreme Court, becoming the only person ever to hold both offices.
29 Oct

Sacco and Vanzetti
United States: Second trial of Sacco and Vanzetti in Boston, Massachusetts.
11 Nov

Arlington National Cemetery
The Tomb of the Unknowns is dedicated by US President Warren G. Harding at Arlington National Cemetery.