クルチ・アルスラーン1世
Likely motivated by many factors, religious as well as secular, William joined the Crusade of 1101, an expedition inspired by the success of the First Crusade in 1099. To finance it, he had to mortgage Toulouse back to Bertrand, the son of Raymond IV. William arrived in the Holy Land in 1101 and stayed there until the following year. His record as a military leader is not very impressive. He fought mostly skirmishes in Anatolia and was frequently defeated. His recklessness led to his being ambushed on several occasions, with great losses to his own forces. In September 1101, his entire army was destroyed by the Seljuk Turks led by Kilij Arslan I at Heraclea; William himself barely escaped, and, according to Orderic Vitalis, he reached Antioch with only six surviving companions. (See Army of William IX on the Crusade of 1101.)