In order to restore the region to Byzantine control, he led a series of well planned and executed campaigns against the Turks, one of which resulted in the reconquest of the ancestral home of the Komnenoi at Kastamonu (Kastra Komnenon); he then left a garrison of 2,000 men at Gangra. John quickly earned a formidable reputation as a wall-breaker, taking one stronghold after another from his enemies. Regions that had been lost to the empire since the Battle of Manzikert were recovered and garrisoned. Yet resistance, particularly from the Danishmends of the northeast, was strong, and the difficult nature of holding the new conquests is illustrated by the fact that Kastamonu was recaptured by the Turks even as John was in Constantinople celebrating its return to Byzantine rule. John persevered, however, and Kastamonu soon changed hands once more. In the spring of 1139, the emperor campaigned with success against Turks, probably nomadic Turkomans, who were raiding the regions along the Sangarios River, striking their means of subsistence by driving off their herds. He then marched for the final time against the Danishmend Turks, his army proceeding along the southern coast of the Black Sea through Bithynia and Paphlagonia. The breakaway Byzantine regime of Constantine Gabras in Trebizond was ended, and the region of Chaldia brought back under direct imperial control. John then besieged but failed to take the city of Neocaesarea, in 1140. The Byzantines were defeated by the conditions rather than by the Turks: the weather was very bad, large numbers of the army's horses died, and provisions became scarce. In the Levant, the emperor sought to reinforce Byzantine claims to suzerainty over the Crusader States and to assert his rights over Antioch. In 1137 he conquered Tarsus, Adana, and Mopsuestia from the Principality of Armenian Cilicia, and in 1138 Prince Levon I of Armenia and most of his family were brought as captives to Constantinople. This opened the route to the Principality of Antioch, where Raymond of Poitiers, Prince of Antioch, and Joscelin II, Count of Edessa, recognized themselves as vassals of the emperor in 1137. Even Raymond II, the Count of Tripoli, hastened northwards to pay homage to John, repeating the homage that his predecessor had given John's father in 1109. There then followed a joint campaign as John led the armies of Byzantium, Antioch, and Edessa against Muslim Syria.