1550
Year 1550 was a common year starting on Wednesday of the Julian calendar.
Events
January–March
- January 6 - Spanish Captain Hernando de Santana founds the city of Valledupar, in modern-day Colombia.
- February 7 - After a 10-week conclave in Rome to elect a new Pope, Giovanni Maria Ciocchi del Monte, Bishop of Palestrina, is selected on the 61st ballot after Reginald Pole of England falls two votes short of winning. Ciocchi del Monte takes the name Pope Julius III and is crowned the next day, succeeding the late Pope Paul III.
- February 25 - In Oita, Ōita Prefecture, an attack within the Ōtomo clan of Japanese samurai takes place after clan leader Ōtomo Yoshikazu seeks to disinherit his oldest son and to make his third son, Ōtomo Shioichimaru, as his designated successor. Supporters of the oldest son, Ōtomo Yoshishige, invade Yoshikazu's home and kill Shioichimaru and four other family members.
- 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.
- * 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–June
- 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.
- April 30 - King Tabinshwehti of Burma is assassinated by two of his bodyguards while he is on a hunting trip. The two swordsmen, sent by Smim Sawhtut, Governor of Sittaung, behead the King, and a civil war begins as major governors rebel against the new Burmese King Bayinnaung.
- May 6 - Italian Protestant Michelangelo Florio, jailed since 1548 before being brought to trial for and sentenced to death for heresy, escapes from prison and is able flee to France.
- May 15 - The vestments controversy is resolved in the Church of England with a compromise on the style of clothing worn by Anglican priests. John Hopper is allowed ordination as the Bishop of Gloucester without being required to wear Anglican vestments, but must not forbid anyone in his bishopric from wearing the vestments if they wish.
- May 20 - The Spanish Catalan city of Cullera is plundered by the Ottoman Empire General Dragut Reis, and most of its inhabitants are sold into slavery in Algeria.
- June 12 - The city of Helsinki is founded by King Gustav I of Sweden.
- June 28 - Capture of Mahdia : The Spanish Armada arrives in North Africa to begin the process of capturing the fortress of Mahdia from control of the Ottoman Empire.
July–September
- July 21 - The Society of Jesus is approved by Pope Julius III.
- July 25 - Capture of Mahdia : Troops commanded by Ottoman General Turgut Reis make a counterattack on the Spanish invaders, led by General Andrea Doria. Both sides sustain heavy losses, and the Spanish succeed in forcing the Ottomans to retreat back inside Mahdia.
- August 5 - The University of Santa Catalina is authorized in Spain by a canonical bull from Pope Julius III.
- September 2 - King Bayinnaung of Burma begins a four-month siege of the former Burmese capital, Toungoo, occupied by the king's rebellious brother Minkhaung.
- September 10 - Spanish troops, commanded by Genoa's General Andrea Doria, capture the Tunisian fortress of Mahdia from the Ottoman Empire after fighting that began on June 28.
October–December
- October 2 - Battle of Sauðafell in Iceland: Daði Guðmundsson of Snóksdalur defeats the forces of Catholic Bishop Jón Arason, resulting in Iceland becoming fully Protestant. Arason is captured; he is executed, along with his two sons, on November 7.
- October 16 - Altan Khan crosses the Great Wall of China and besieges Beijing, burning the suburbs.
- November 25 - Luis de Velasco becomes the second Viceroy of New Spain, which encompasses all Spanish territory in North America and Central America. Velasco succeeds Antonio de Mendoza, the first Viceroy, who has been ordered to become the Viceroy of Peru.
- December 29 - Bhuvanaikabahu VII, King of Kotte on most of the island of Sri Lanka, is assassinated by a gunman hired by the government of Portuguese India.
Date unknown
- 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 Guanajuato in Mexico stimulates silver rushes.