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William was the most prominent member of the embassy that Baldwin II sent to France in 1127 to start negotiations about the marriage of his eldest daughter, Melisende, and Fulk V of Anjou. William escorted Fulk from France to Jerusalem in 1129. Fulk, who succeeded Baldwin II in 1131, dismissed his father-in-law's many officials, but William retained the office of constable. Although most historians agree that he died in 1143 or 1144, Hans Eberhard Mayer says that Melisende forced William into exile after Fulk died in 1143, but he regained Galilee from her son, Baldwin III of Jerusalem in 1153.