Former Qin
In 383, as Former Qin launched a major assault with intent to destroy Jin once and for all, Xie Xuan and his Beifu Force was sent to the frontline, reporting to the command of his uncle Xie Shi (謝石). Xie Shi, initially intimidated by the much larger Former Qin force, considered merely trying to block Former Qin progress without major engagement, but after he was advised otherwise by the Former Qin ambassador Zhu Xu—a Jin general who was captured by Former Qin in 379 but who secretly remained loyal to Jin—and chose to engage Former Qin forward troops that arrived first. Xie Xuan, charged with engaging Former Qin forces, along with Liu Laozhi, dealt them minor defeats, reducing their morale. When Former Qin troops gradually arrived, the Former Qin and Jin forces became stalemated across the Fei River (which no longer exists but probably flowed through Lu'an, Anhui, near the Huai River).