Task: Question Generation
Input (English): Passage: Baldwin de Burg was a nephew of Baldwin I of Jerusalem and the Count of Edessa from 1100 to 1118. In 1118 his uncle died and he became King Baldwin II of Jerusalem. In the Battle of Ager Sanguinis, fought near Sarmada on 28 June 1119, the Franks suffered a disastrous defeat by the forces of Ilghazi, the ruler of Mardin. Later that year Baldwin regained some territory, but the Franks were seriously weakened. Baldwin asked for help from Pope Callixtus II. The pope forwarded the request to Venice. The terms of the crusade were agreed through negotiations between the envoys of Baldwin II and the doge of Venice. Once the Venetians decided to participate, Pope Callixtus II sent them his papal banner to signify his approval, At the First Council of the Lateran he confirmed that the Venetions had crusader privileges, including remission of their sins. The church also extended its protection to the families and property of the crusaders. In 1122 the Doge of Venice, Domenico Michiel, launched the seaborne crusade. The Venetian fleet of more than 120 ships carrying over 15,000 men left the Venetian Lagoon on 8 August 1122. This seems to have been the first crusade in which the knights brought their horses with them. They invested Corfu, then a possession of the Byzantine Empire, with which Venice had a dispute over privileges. In 1123 Baldwin II was captured by Balak of Mardin, emir of Aleppo, and imprisoned in Kharput. Eustace Graverius became regent of Jerusalem. The Venetians abandoned the siege of Corfu when they heard this news, and reached the Palestinian coast in May 1123.
Output (English): What caused the Venetians to abandon the siege of Corfu?