Gongsun Kang
Cao Cao assumed effective rule over all of northern China. Suffering mutiny amongst their own troops, Yuan Shang and Yuan Xi fled to the Wuhuan chieftains for aid. The Wuhuan chieftain Tadun assisted the Yuan brothers and started raiding Cao's territory. In 207, Cao Cao led a daring campaign beyond Chinese borders in hopes of destroying the Yuans once and for all. He fought an alliance of Wuhuan chieftains at the Battle of White Wolf Mountain. Though outnumbered and isolated, Cao Cao emerged victorious due to cleverly engineering his supply lines by digging two new canals and flanking the enemy, killing Tadun and forcing the Yuans to flee once again. This time, they went to Gongsun Kang for help, but he executed them and sent their heads to Cao Cao, granting him nominal control over You Province. Meanwhile, the northern tribes were now terrified of Cao Cao. Most of the remaining Wuhuan submitted to him, along with the Xianbei and Xiongnu.