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Year 1241 (MCCXLI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar.
- March 18 – Battle of Chmielnik (Mongol invasion of Poland): The Mongols overwhelm the feudal Polish armies of Sandomierz and Kraków provinces, and plunder the abandoned city of Kraków.
- April 9 – Battle of Legnica: The Mongols, under the command of Baidar, Kadan and Orda Khan, defeat the feudal Polish nobility, including the Knights Templar.
- April 11 – Battle of Mohi: Batu Khan and Subutai defeat Béla IV of Hungary. The battle is the last major event in the Mongol Invasion of Europe.
- April 27 – Battle of Sajo: The Mongols defeat Bela IV of Hungary.
- May – Battle of Giglio: an Imperial fleet defeats a Genoan fleet in the Tyrrhenian Sea.
- May 10 – Battle of Cameirge in Ulster: The Milesian Irish septs of the Ó Dónaills from Donegal, the Ó Néills from Armagh and the Ó Dochartaighs of Connacht defeat the last Tuatha Dé Danann sept, the Meic Lochlainn of Tír Eoghain and Inishowen under Domhnall mac Muirchertaigh Mac Lochlainn. From now on the Kings of Tír Eoghain will all be of the Ó Néill dynasty, Brian Ua Néill becoming sole ruler.
- Early northern summer – A succession crisis or other priorities results in the Mongols withdrawing behind their river barrier into the Ukraine and the Russias, leaving Central Asian and far Eastern Europe peoples tributary to the Khanates, but leaving Poland and Hungary to begin recovery and reorganization.
- August 29 – After Henry III of England's invasion of Wales, the Treaty of Gwerneigron is signed by him and Dafydd ap Llywelyn, curbing the latter's authority and denying him royal title.
- September 23 – Snorri Sturluson, Icelandic saga writer, is murdered by Gissur Þorvaldsson, an emissary of King Haakon IV of Norway.
- October 25 – Pope Celestine IV succeeds Pope Gregory IX, as the 179th pope.
- Emperor Lizong of Song China accepts the Neo-Confucian teachings of the late Zhu Xi, including his commentary on the Four Books. This will have an impact upon the philosophical schools of surrounding countries as well, including Korea, Japan, and Vietnam.
- Livonian Crusade: The Estonian rebellion of 1237 is suppressed on Saaremaa Island, by the Livonian Order.