By 211, the situation in the south had stabilized and Cao Cao decided to crush his remaining enemies in the north, to the west of Chang'an (in Zuopingyi Commandery). In Hanzhong commandery on the Han River, in the north of Yi Province, Zhang Lu lived in revolt against the Han dynasty, running his own theocratic state. Cao Cao sent Zhong Yao with an army to force Zhang Lu's surrender. However, this disturbed a number of warlords in the Wei River valley and the wider Liang Province, who united under Han Sui and Ma Chao to oppose Cao Cao, believing that his maneuvers against Zhang Lu were actually directed at them. Cao Cao personally led the army against this alliance, and outmaneuvered the rebel army at every turn in the Battle of Tong Pass. The alliance shattered and many of the leaders were killed. Cao Cao spent the next month or two hunting down some of the leaders, many of whom surrendered to him. He left Xiahou Yuan to clear up affairs in the region and returned home in 212. In 213, he launched an invasion into Sun Quan's territory across the river Huai, but was defeated in the Battle of Ruxu, which confirmed Sun's control of the south.