1140

Events

Spring – King Fulk of Jerusalem confronts Imad al-Din Zengi, Seljuk ruler (atabeg) of Mosul, near Dara'a in southern Syria.David Nicolle (2009). Osprey: Campaign 204. The Second Crusade 1148: Disaster outside Damascus, p. 15. {{ISBN|978-184603-354-4}}. Turkish forces under Mu'in al-Din (supported by the Crusaders) besiege Banias.

Spring – King Conrad III enfeoffs Henry II (Jasomirgott), a member of the House of Babenberg, with the County Palatine of the Rhine (belonging to the Holy Roman Empire).
Summer – King Roger II promulgates the Assizes of Ariano (a series of laws to rule the Norman Kingdom of Sicily) after the pacification of southern Italy.
December 21 – Siege of Weinsberg: Conrad III captures the castle at Weinsberg during the civil war between the Staufers and the Welfs in Germany.

Summer – King Stephen appoints Geoffrey de Mandeville as Earl of Essex for his support during the civil war against Matilda (Stephen's cousin).
The town of Lanark in Scotland is made a Royal Burgh by King David I, giving it merchant privileges relating to government and taxation.

August 21 – Jin–Song Wars – Battle of Yancheng: Chinese forces under the command of Yue Fei defeat a numerically superior Jin army led by Wuzhu.

June 3 – Pierre Abelard, a French theologian, is condemned for heresy by the Council of Sens. He sets out for Rome to present his defense to Pope Innocent II.
September 8 – Sephardi Jewish philosopher Judah Halevi, having completed the Kuzari, arrives in Alexandria on a pilgrimage to Palestine.
The first Cistercian monastery in Spain is founded in Fitero.{{cite journal|last=Fletcher|first=R. A.|title=Reconquest and Crusade in Spain c. 1050-1150|journal=Transactions of the Royal Historical Society|year=1987|volume=37|series=5|pages=31–47 [45]|doi=10.2307/3679149 |jstor=3679149|s2cid=154629568 }} The order enjoys a rapid expansion in the region in the following 15 years.

Gratian, an Italian monk and canon lawyer, founds the science of Canon law with the publication of the Decretum Gratiani (approximate date).