周德威
When Li Cunxu ordered his major general Zhou Dewei to attack the rival state Yan in late 911, Yang Tan served under Zhou in the campaign. After Jin forces under Zhou and Li Cunxu himself destroyed Yan around the new year 914, and Li Cunxu subsequently commissioned Zhou as the military governor ("Jiedushi") of Lulong Circuit (盧龍, headquartered in modern Beijing)—the main circuit of the former Yan state—Yang appeared to remain under Zhou's command at Lulong. In a subsequent campaign when the Khitan Empire attacked Xin Prefecture (新州, in modern Zhangjiakou, Hebei), apparently in 917, Yang served under Zhou in resisting the Khitan. During that battle, Yang suffered an injury to one of his arms—probably a fracture—that eventually led to the arm becoming useless. He thus left military service and stayed at home thereafter.