 However, the warlords Ma Chao and Han Sui, who were based in the Guanzhong region in between Cao Cao's territories and Hanzhong Commandery, thought that Cao Cao wanted to attack them so they started a revolt against the Han central government, leading to the Battle of Tong Pass and subsequent battles.Although Cao Cao's forces emerged victorious against the Guanzhong warlords, they were in no condition to continue attacking Hanzhong Commandery so they retreated.Ma Chao escaped to Hanzhong Commandery after his defeat and pledged allegiance to Zhang Lu, who considered marrying his daughter to him.