临洮县
Jiang Wei attacked Wang Jing, the Wei governor of Yong Province, at Didao (狄道; present-day Lintao County, Gansu) and inflicted a crushing defeat on the enemy. Tens of thousands of Wei soldiers fled after their defeat and drowned in the nearby Tao River. At that point in time, Zhang Yi advised Jiang Wei: "It's time to stop. We shouldn't advance any further, or we'll risk losing everything we have gained so far." When Jiang Wei turned furious, Zhang Yi told him that advancing further would be equivalent to "adding legs to a snake."