1240 (timeline)

Year **1240** (MCCXL) was a leap year starting on Sunday of the Julian calendar.

It corresponded to the Byzantine years of 6748–6749 and the Islamic years of 637–638.

## Events

### Europe

#### France

* 6 January – Louis IX of France announces he seeks the annulment of his sister Isabella's marriage to King Theobald I of Navarre, Count of Champagne, citing her wish to become a nun, and promises to go on a Crusade.
* Spring – Theobald I of Navarre invades France and is elected King of France by numerous rebellious vassals, among them King Arthur I of England.
* The Battle of Angers takes places, resulting in a pyrrhic draw.
* Kingdom of Aragon joins the war.
* Henry I, Duke of Brabant, declares war on France, citing the alleged captivity of his granddaughter Matilda, widow of Prince Robert of France, Count of Artois, at Paris.
* Matilda of Brabant, Dowager Countess of Artois, marries Reginald, the younger brother of Matthias, Duke of Lorraine, who becomes Count of Artois.
* Flanders is occupied by the Duke of Brabant.
* France achieves several victories against the Navarrese and the English, occuping Normandy, Aquitaine, Les Marches, Limoges and Périgod.

#### England

* Henry, Lord of Ireland is assassinated on his way to London. His death is blamed on King Henry III of England.
* The Pale rebellion begins.
* Henry III of England is excommunicated by Pope Gregory IX at the behest of Louis IX of France, citing the murder of Henry, Lord of Ireland

#### Italy

* Frederick I of Sicily banishes Papal authorities from the Kingdom of Sicily in protest at Henry III's excommunication. He is excommunicated in turn.
* War breaks out between Sicily and the Papacy.
* The Battle of Ostia takes place. Sicilian navy is forced back to Palermo by the Genoese navy.
* The Sicilians are defeated at the Battle of Lucca.
* The New Lombard League is formed to oppose the Sicilians in Tuscany and Lombardy. They also renounce their allegiance to the Holy Roman Empire.
* Frederick I sacks Beneveto and marches on Rome, occupying Umbria.
* Hafsids invade Sicily, taking the island of Malta.
* Battle of Messina takes place between the Venetian fleet and the Hafsid fleet, ending in Venetian victory.
* Hafsids lay siege to Palermo, Syracuse and Messina.

#### Iberia

* Navarre is conquered by Aragon.
* Castille intervenes in the Navarrese war and pushes back the Aragonese from Navarre.
* Enrique I of Castille is proclaimed King of Navarre.
* Ferdinand I of Aragon succeeds as King of Aragon and a regency council is assembled, after peace is made with Castille.
* Ramon Berenguer IV, Count of Provence, demands the destitution of Queen Eleanor of Aragon from the regency council.

#### Scandinavia

* King Valdemar II of Denmark proposes the Code of Jutland, an unified law code for the entire kingdom.
* An assassination attempt is made against Prince Valdemar of Denmark, incriminating the King Haakon IV of Norway.

#### Eastern Europe

* The Battle of Lublin takes place. Mongols decimate the Polish royal army.
* The Mongols plunder the Duchy of Krakow.
* The Mongols defeat the Hungarians in battle and invade the Great Hungarian Plain.
* King Wenceslaus I of Bohemia unsuccessfully attempts to hold an election in Poland. The Grand Duchy is engulfed by civil war as the Duke Kuyavia, the Duke of Masovia and the Duke of Greater Poland try and claim the throne.

#### Byzantium

* The Mongols invade Byzantine Anatolia and defeat all Byzantine forces in the region.
* Ivan Asen II of Bulgaria becomes a Mongol tributary, as does Serbia.
* The Battle of Adrianople results in Byzantine victory and marks the first Mongol defeat in Europe.
* The Mongols retreat following the death of Ögodei Khan.

### Middle East

* Isabella, Queen of Armenia, pledges herself as a tributary to the Mongols and attempts to kidnap King Aimery IV of Jerusalem.
* Maurice II of Egypt is defeated in battle against the Mamluks and Alexandria is put under siege.

### Northern Africa

* Abu Zakariya Yahya, Caliph of the Hafsid Caliphate, declares a jihad for the island of Sicily.

## Deaths

* Princes Robert, Count of Artois, and Alphonse, son of Louis VIII, younger brothers of Louis IX of France, slain at the Battle of Angers.
* Arthur I of England, who died of a crossbow wound four days after the Battle of Angers.
* 27 June – Henry, Lord of Ireland, murdered on the road alongside Gilbert Marshal .
* Jaime I of Aragon at the Battle of Alfaro.
* Sancha, Queen of León.
* Henryk II, Grand Duke of Poland, and his three eldest sons Boleslaw, Mieszko and Henryk, at the Battle of Lublin.
* King Emeric of Hungary, of old age and a broken leg acquired in battle against the Mongols.
* Ögödei Khan.