After experiencing the invasion by the Jurchen, Yun Kwan realized that Goryeo lacked efficient cavalry units, and requested permission from
King Sukjong to train and reorganize the current Goryeo military into a professional army that would contain well-trained cavalry units. Finally, in 1107, General Yun led the newly formed Goryeo army, a force of approximately 170 thousand men called
Pyŏlmuban, and attacked the Jurchen tribes. Though the war lasted for several years, the Jurchen were ultimately defeated, and surrendered to Yun Kwan. To mark the victory, General Yun built nine fortresses to the northeast of the Goryeo-Jurchen borders (). In 1108, however, General Yun was given orders to withdraw his troops by Goryeo's new ruler,
King Yejong. Due to manipulation and court intrigue from opposing factions, he was discharged from his post in 1108. Along with this, the opposing factions fought to make sure that the new nine fortresses were returned to the Jurchens. Soon after, Yun Kwan was released from his prison in 1110, and was offered a chance to return to his duties as general, but he refused and returned to his hometown. A year later, in 1111, Yun Kwan died to illness. == Aftermath ==