 Complete the following phrase:  After Liu Biaos death in 208, his younger son Liu Cong, who succeeded him, surrendered to Cao Cao when Cao led his forces on a campaign in southern China. Yi Ji joined Liu Bei on a journey southward towards Xiakou 夏口; present-day Wuhan, Hubei, which was guarded by Liu Biaos elder son Liu Qi and was independent of Cao Caos control. Yi Ji became an official under Liu Bei since then. In the 210s, after Liu Bei 