Events

Europe

War and politics

• July – William II, Count of Holland defeats the Flemish army at Westkapelle.

• July 6 – Mindaugas is crowned as King of Lithuania.

• A series of naval wars begins between the Italian city-states of Genoa and Venice, which will continue sporadically until 1371.

• King Henry III of England meets with English nobles and church leaders to reaffirm the validity of the Magna Carta.

• Pope Innocent IV returns to Rome, having left 9 years earlier in 1244 to depose Frederick II, Holy Roman Emperor, and being unable to return until after Frederick's death, due to the agitation throughout Europe caused by that action.

• Having rebuffed the armed forces of Conrad IV of Germany, Pope Innocent IV offers Sicily to Edmund, son of King Henry III of England.

• Halych-Volynia becomes a vassal state to the expanding Mongol Empire.

Culture

• Matthew Paris writes Historia Anglorum, a work on English history.

• The Basilica of San Francesco, the earliest important structure in the Italian Gothic style of architecture, is completed in Assisi, Italy.

• Sligo Abbey is built in Sligo, Ireland.

• The Domus Conversorum, a building and institution in London for Jews who had converted to Christianity, is established by King Henry III of England.

• La Sorbonne is founded by Robert de Sorbon.

Asia

• April 28 – Nichiren, a Japanese Buddhist monk, declares his intent to preach the Lotus Sutra and Nam Myoho Renge Kyo as the true Buddhism, thus founding Nichiren Buddhism.

• May – King Louis IX of France dispatches William of Rubruck from Constantinople on a missionary journey to convert the Tatars of central and eastern Asia. Later that year, William records the first meeting between European Christians and Buddhists.

• The Mongol Empire launches attacks on the Muslim cities of Baghdad and Cairo.

• The Mongol Empire destroys the Kingdom of Dali in modern Yunnan and incorporates the region into their empire.

• Kublai Khan introduces the baisha xiyue song and dance suite to the music of Yunnan.

• The Chinese era Baoyou begins in the Southern Song Dynasty of China.

• The Mongols defeat the Thai confederacy.

Births

• October 17 – Saint Ivo of Kermartin, French canon lawyer

• John I, Duke of Brabant (d. 1294)

• Hugh II of Cyprus (d. 1267)

Deaths

• January 19 – Dogen, Japanese founder of the Soto school of Zen Buddhism

• July 8 – Theobald IV of Champagne (b. 1201)

• August 11 – Clare of Assisi, Italian follower of Francis of Assisi (b. 1194)

• September 23 – Wenceslaus I, King of Bohemia

• October 9 – Robert Grosseteste, English statesman and theologian

• Saint Richard of Chichester

• King Henry I of Cyprus (b. 1217)

• Amadeus IV of Savoy (b. 1197)