The 1340s

1340 CE32 entries

• 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 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.
• October 30 – Battle of Río Salado in Spain: The kings of Castile and Portugal defeat the Nasrid ruler of Granada and his Moroccan allies.

1341 CE36 entries

• January 18 – The Queen's College, a constituent college of the University of Oxford in England, is founded.
• September–October – The Byzantine civil war of 1341–1347 (between John VI Kantakouzenos and the regency for the infant John V Palaiologos) breaks out.
• A great flood in the river Periyar in modern-day southern India leads to the river changing its course, the closing of Muziris, the opening up of Cochin (Kochi) harbour, submersion of some islands, and birth of some new islands.

1342 CE26 entries

• January 21–June 27 – An-Nasir Ahmad, Sultan of Egypt, rules prior to being deposed by his half-brother As-Salih Ismail.
• July 18 – Battle of Zava: Mu'izz al-Din Husayn defeats the Sarbadars.
• August 15 – Louis "the Child", age 4, succeeds his father, Peter II, as king of Sicily and duke of Athens; he is crowned on September 15 in Palermo Cathedral.

1343 CE25 entries

• May 4 – St. George's Night Uprising: The "Four Estonian kings" are murdered, at the negotiations with the Livonian Order.
• August 15 – Magnus IV of Sweden abdicates from the throne of Norway, in favor of his son Haakon VI of Norway. However, Haakon is still a minor, allowing Magnus to remain de facto ruler.
• August 31 – A naval league is formed between the Pope, the Republic of Venice, the Knights Hospitaller and the Kingdom of Cyprus, to prepare the Smyrniote Crusades.

1344 CE30 entries

• March 26 – Reconquista: The Siege of Algeciras (1342–44), one of the first European military engagements where gunpowder is used, ends with the Muslim city of Algeciras surrendering and being incorporated into the Kingdom of Castile.
• April 23 – The St. George's Night Uprising: The Livonian Order hangs Vesse, the rebel Estonian Elder of Saaremaa Island.
• October 24 – Smyrniote Crusade: A Christian fleet succeeds in taking the port city of Smyrna from the Aydinid Turks.

1345 CE37 entries

1346 CE40 entries

1347 CE42 entries

• January 26 – Charles University in Prague is founded by a bull issued by Pope Clement VI, at the request of Charles I, King of Bohemia.
• February 2 – The Byzantine civil war of 1341–1347 between John VI Kantakouzenos and the regency for John V Palaiologos ends with Kantakouzenos entering Constantinople.
• December 25 – The first cases of the plague are recorded in the city of Split, in Croatia.

1348 CE28 entries

• April 23 – Edward III of England creates the first English order of chivalry, the Most Noble Order of the Garter.
• July 6 – A papal bull is issued by Pope Clement VI, protecting Jews against popular aggression during the Black Death pandemic.
• November 1 – The anti-royalist Union of Valencia attacks the Jews of Murviedro because they are serfs of the King of Valencia and thus "royalists".

1349 CE32 entries

• January 22 – An earthquake affects L'Aquila in southern Italy with a maximum Mercalli intensity of X (Extreme), causing severe damage, and leaving 2,000 dead.
• August 24 – The Black Death breaks out in Elbing (Poland).
• October 20 – Pope Clement VI publishes a papal bull that condemns the Flagellants.