1340
Year 1340 was a leap year starting on Saturday of the Julian calendar.
Events
- January 26 - King Edward III of England declares himself King of France at Ghent, Flanders.
- March 6 - Bohemian Crusade: The Church authorizes a military expedition against heretics.
- April 8 - Marinid galleys, under the command of Muhammad ibn Ali al-Azafi, rout the Castellan fleet, off the coast of Algeciras.
- April–July - Trapezuntine Civil War: An abortive uprising occurs against Irene Palaiologina of Trebizond, the first of a number of coups, revolts, and succession disputes.
- June 7 - Rotterdam is officially declared a city.
- June 24
- * Hundred Years' War: Battle of Sluys - The English fleet, under the command of Edward III of England, battles the French fleet, under that of Admiral Hugues Quiéret and treasurer Nicolas Béhuchet, assisted by Genoese mercenary galleys under Egidio Bocanegra, on the Low Countries coast. The French fleet is virtually destroyed, and both of its commanders are killed.
- * Valdemar IV of Denmark, son of deceased King Christopher II, is elected to the throne, following 8 years of interregnum.
- July 26 - Hundred Years' War - Battle of Saint-Omer: The French defeat the English.
- September 25 - Hundred Years' War: The temporary Truce of Espléchin is signed between England and France.
- October 30 - Battle of Río Salado in Spain: The kings of Castile and Portugal defeat the Nasrid ruler of Granada and his Moroccan allies.
Date unknown
- Europe has about 74 million inhabitants.
- An epidemic in northern Italy is recorded by Augustine of Trent, in his Epistola astrologica.
- The Monarchy of Japan reaches its 2,000 year anniversary.