While Sultan Mes'ud reinforced his power and influence in Anatolia, Imaddedin Zenhi had abolished the Crusade County of Urfa in the year of 1144. This success of the Turks led the Crusades to worry about the situation and a great anxiety was awakened in Europe. The emperor of the Germany, Konrad III and the king of France, St. Louis set in motion as the leader of their armies. Konrad who arrived in Istanbul before St. Louis was immediately directed to Anatolia by the Emperor Manuel. Konrad who followed the trace of the First Crusade encountered with Sultan Mes'ud when he arrived in the savanna of Eskisehir. In the war that took place in October 1147, the Germans were defeated by the Seljuks in a crushing manner and they retreated. Sultan Mes'ud caught the army of the German Emperor that was composed of 75.000 people near Ceyhan. In this terrible war, the German Emperor could save his life with only 5.000 people of his army and took shelter in Iznik in great difficulties. St. Louis who heard of the news about the defeat of the German army abstained from the penetration into the Central Anatolia and he was obliged to follow the destination of Ephesus-Denizli-Antalya. Nevertheless, St. Louis was subjected to the raids of Turkmens on the way and he lost great casualties. He could go to Akka with the ships from Antalya. The army under the command of the king of France was composed of 150,000 people. This army was also defeated within the environs of Yalvac and he suffered great losses and casualties. Those who survived united with the troop of the German army that was composed of 5.000 people who had saved their lives and they could land in Akka through only the marine routes.
Pursuant to his victory against the Crusades, Sultan Mes'ud defeated the Syrian Crusades by means of the military expeditions in 1149 and 1150. Thus, he conquered Maras, Goksun, Ayintab, Ra'ban and Deluk. He subdued the Danismendli people in Sivas and Malatya and he penetrated into Cilicia. He captured some cities and castles in this region that were dominated by Armenians in the year of 1154. When he decided to conquer the entire Cilicia, he immediately returned upon the epidemic of plague that broke out. Pursuant to his sultanate for 39 years, Sultan Mes'ud died in the year of 1155. Sultan Mesud had prevented the dissolution of Turkey Seljuks State through a successful policy and a patient struggle. He developed the state that was ascendant within the environs of Konya into a dominant state in Anatolia. His victories that he had won against the Crusades led to the inclusion of his name among the greatest fighters of Turks and Islam. Through his justice and strong administration, he could disconnect the Christians from the Byzantine and subdue them. The first public works and the modern facilities of the Seljuk State were created in his period.