Complex sentence: Lu Xun sent a close aide, Han Bian (韓扁), to deliver a report to Sun Quan, but on the return journey, Han encountered the enemy at Mianzhong (沔中) and was captured.
Split into simpler sentences: Lu Xun sent a close aide, Han Bian (韓扁), to deliver a report to Sun Quan. On the journey back, Han Bian encountered the enemy at Mianzhong (沔中) and was captured.