1621

Events 
 February 9 – Gregory XV is elected pope.
 February 17 – Miles Standish is appointed as first commander of Plymouth Colony.
 March 16 – Samoset, a Wampanoag, visits the settlers of Plymouth Colony and greets them, "Welcome, Englishmen! My name is Samoset."
 March 22 – The Pilgrims of Plymouth Colony sign a peace treaty with Massasoit of the Wampanoags.
 April 5 – The Mayflower sets sail from Plymouth on a return trip to Great Britain.
 The Swedish city of Gothenburg is founded by Gustavus Adolphus
 Riga falls under rule of Sweden
 Willebrord Snell discovers the laws of refraction.