Year 1550 (MDL) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. Events January–June January 6 – Spanish Captain Hernando de Santana founds the city of Valledupar, in modern-day Colombia. February 8 – Pope Julius III succeeds Pope Paul III as the 221st pope. March 12 – Arauco War: Battle of Penco – Several hundred Spanish and indigenous troops under the command of Pedro de Valdivia defeat an army of 60,000 Mapuche in modern-day Chile. March 12 – Acapulco is founded by 30 families sent from Mexico City March 24 – "Rough Wooing": England and France sign the Treaty of Boulogne, by which England withdraws from Boulogne in France and returns territorial gains in Scotland. March 29 – Sherborne School in England is refounded by King Edward VI. April 16 – The Valladolid debate on the rights and treatment of indigenous peoples of the Americas by their Spanish conquerors opens at the Colegio de San Gregorio in Valladolid, Castile. June 12 – The city of Helsinki, Finland (belonging to Sweden at this time) is founded by King Gustav I of Sweden. July–December July (at least) – John Dee finishes his studies at the Old University of Leuven. July 7 – Chocolate is introduced to Europe. July 21 – The Society of Jesus (Jesuits) is approved by Pope Julius III. October 2 – Battle of Sauðafell in Iceland: Daði Guðmundsson of Snóksdalur defeats the forces of Catholic Bishop Jón Arason who is captured and executed, resulting in Iceland becoming fully Protestant. Date unknown Altan Khan crosses the Great Wall of China and besieges Beijing, burning the suburbs. The summit level canal between the Alster and the Trave in Germany ceases to be navigable. The first grammatical description of the French language is published by Louis Maigret. The first book in Slovene, Catechismus, written by Protestant reformer Primož Trubar, is printed in Schwäbisch Hall, Holy Roman Empire. Nostradamus' first almanac is written. Approximate date – The discovery of silver at Zacatecas and Guanajuato in Mexico stimulates silver rushes. Births January 18 – Tsugaru Tamenobu, Japanese daimyō (d. 1607) February 1 – John Napier, Scottish mathematician (d. 1617) February 17 – Philip of Hohenlohe-Neuenstein, Dutch army commander (d. 1606) February 22 – Charles de Ligne, 2nd Prince of Arenberg (d. 1616) March 6 – Michelangelo Naccherino, Italian sculptor (d. 1622) March 8 – William Drury,