1278Centuries: 12th century - 13th century - 14th century
- August 26 - Ladislaus IV of Hungary and Rudolph I of Germany defeat the Bohemians in the Battle of Marchfield.
- A pareage establishes joint Spanish/French suzerainty in Andorra.
- John Peckham succeeds Richard Kilwardby as archbishop of Canterbury, Kilwardby being appointed as a cardinal-bishop in Italy.
- Llywelyn the Last marries Eleanor de Montfort after making concessions to Edward I of England.
- The Chapel of St Leonard of Blakemore in Buckinghamshire is founded by the Bishop of Lincoln.
- Wenceslaus II becomes king of Bohemia.
- Charles I of Sicily inherits Principality of Achaea.
- Zhao Bing succeeds Zhao Shi as emperor of China.
- Ramkhamhaeng becomes ruler of the Sukhothai kingdom in Thailand.
- Deal is named a Cinque Port.
- Iserlohn receives city rights.