August – Emperor Frederick II musters a German expeditionary force in Apulia. The crowded conditions and high heat contribute to discontent and disease among the assembled troops. On September 24, an epidemic of malaria enfeebles the army at Brindisi. Several thousand Crusaders led by Henry IV, duke of Limburg, and French and English mercenaries under the bishops Peter des Roches and William Briwere, arrive at Acre.[1]
September – A second contingent joined by Frederick II, departs from Brindisi to the Levant. On September 11, during the second day of the voyage, one of Fredericks' companions, Louis IV of Thuringia, dies of an illness (possibly cholera) at Otranto. Frederick also becomes sick and decides to return home, while sending the rest of the Crusader fleet (20 galleys) to Acre. There, they fortify the coastal towns of Caesarea and Jaffa.[2]
November 24 – Prince Leszek I (the White) is assassinated in an ambush on a council of Polish dukes in the city of Gąsawa, an event which later becomes known as the Gąsawa Massacre.
Siege of Yinchuan: Mongol forces eliminate the Western Xia (or Xi Xia) and execute Emperor Mo (or Li Xian). Genghis Khan dies during the siege under debated circumstances, but this is kept secret from the army until the siege's end. Yinchuan is pillaged and its entire population is slaughtered or sold into slavery. Genghis orders the imperial family to be executed, effectively ending the Tangut royal lineage.[8]
August 18 – Genghis Khan dies during the fall of Yinchuan after a 21-year reign. His exact cause of death remains a mystery, and is variously attributed to being killed in action against the Western Xia, illness, falling from his horse, or wounds sustained during hunting. Genghis is succeeded by his third son, Ögedei Khan, who becomes the "Great Khan" of the Mongol Empire.[9]
