Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Gaston IV (died 1131), was viscount of BÃ©arn from 1090 to 1131. He was called le CroisÃ©" ("the Crusader") due to his participation in the First Crusade. Gaston succeeded his father Centulle V in 1090. During his rule, the borders of BÃ©arn were established more definitively he defeated the viscount of Dax, and took control of Orthez, Mixe, and Ostabaret by 1105. He also gained MontanÃ©rÃ¨s through his marriage to TalÃ¨se, daughter of the count of Aibar and Javierrelatre and niece of Sancho I of Aragon. Though technically a vassal of the Duchy of Aquitaine, ruled at that time by William IX, Gaston effectively made BÃ©arn an autonomous territory. Before becoming viscount, Gaston had fought in the Reconquista in Spain, and he led a BÃ©arnais contingent on crusade under Raymond IV of Toulouse in 1096. He was one of the lesser knights, but he carried his own standard and commanded his own men. At the siege of Antioch he led one of the divisions in the final battle against Kerbogha. During the power struggle following the capture of Antioch, Gaston deserted Raymond for Godfrey of Bouillon and marched with him to Jerusalem. "