1275: Year

As of the start of 1275, the Gregorian calendar was 7 days ahead of the Julian calendar, which was the dominant calendar of the time.

Europe

War and politics

• April 22 – The first of the Statutes of Westminster are passed by the English parliament, establishing a series of laws in its 51 clauses, including equal treatment of rich and poor, free and fair elections, and definition of bailable and non-bailable offenses.
• Eleanor de Montfort is captured by pirates in the employ of Edward I of England to prevent her marriage to Llywelyn the Last, prince of Wales; she is used as a bargaining chip over the coming years in Edward's attempts to subjugate Llywelyn and Wales.
• Scottish forces defeat the Manx of the Isle of Man in a decisive battle, firmly establishing Scottish rule of the island.
• Third Mongol Golden Horde raid against Lithuania.

Culture, religion, and science

• Jean de Meun completes the French allegorical work of fiction, Roman de la Rose, with a second section; the first section was written by Guillaume de Lorris in 1230.
• The verge escapement, a simple type of escapement used in clocks, is invented (exact year unknown).
• Ramon Llull establishes a school in Majorca to teach Arabic to preachers in an attempt to aid proselytizing to Moors. He also discovers diethyl ether.
• The first main survey of the Hundred Rolls, an English census seen as a follow up to the Domesday Book completed in 1086, is finished; it began in 1274.

Asia

• March – the 200,000 multiethnic troops of the Mongol-led Yuan Dynasty, headed by the Turkish commander Bayan, face a Chinese Song Dynasty army of 130,000 led by the Song Chancellor Jia Sidao. The result is a decisive victory for the Yuan Dynasty, and soon after the much-vilified Jia Sidao is stripped of rank and title, and killed by one of his own guards as he is sent to exile in Fujian by the Song court.
• Invading Mongol forces capture the Chinese city of Suzhou.
• Marco Polo purportedly visits Xanadu, Kublai Khan's summer capital of the Mongol Empire.
• The city of Kunming is made capital of the Yunnan province of the Mongol Yuan Dynasty.
• Nestorian monk Rabban Bar Sauma begin his pilgrimage from China towards Jerusalem
• Chinese astronomers observe a total eclipse of the Sun in China on March 4.

• The era of the tosafot, Medieval commentators on the Talmud, ends (began 1100).
• The population of Bushmen in Basutoland (modern-day Lesotho) is estimated at 125,000.
• The Japanese era Bun'ei ends, and the Kenji era begins.

• September 27 – John II, Duke of Brabant (died 1312)
• William of Alnwick, Franciscan theologian (approximate date; died 1333)
• Bartholomew de Badlesmere, 1st Lord Badlesmere (died 1322)
• Walter V of Brienne, Duke of Athens (approximate date; died 1311)
• Edward Bruce, Scottish nobleman (approximate date; died 1318)
• Dnyaneshwar, Hindu saint and poet (died 1296)
• Gediminas, Duke of Lithuania (approximate date; died 1341)
• Henry VII, Holy Roman Emperor (approximate date; died 1313)
• Mondino de Liuzzi, Italian physician and anatomist (died 1326)
• John Menteith, Scottish nobleman (approximate date; died 1323)
• Giovanni Villani, Florentine writer (approximate date; died 1348)
• Giovanni d'Andrea, Italian jurist

• April 13 – Eleanor of England (born 1215)
• September 24 – Humphrey de Bohun, 2nd Earl of Hereford, Constable of England (born 1208)
• Bohemund VI of Antioch (born 1237)
• Ferdinand de la Cerda, Infante of Castile, Crown Prince of Castile