Around 214, the warlord Liu Bei was fighting for control over Yi Province with the provincial governor Liu Zhang. Ma Chao distrusted Zhang Lu and felt that he was not capable of great achievements, so he planned to defect to Liu Bei. When he heard that Liu Bei was besieging Liu Zhang in Chengdu (Yi Province's capital), he wrote a secret letter to Liu Bei, expressing his desire to serve the latter. Liu Bei was pleased to receive Ma Chao's letter and he exclaimed, "Yi Province is mine." He then sent Li Hui to meet Ma Chao and provide supplies and additional troops to Ma, after which Ma led his forces to the north of Chengdu and joined the siege. Within ten days of Ma Chao's arrival, Liu Zhang gave up resistance and surrendered to Liu Bei.