When the Xiongnu sought an alliance and the matter was being discussed by various officials, Di Shan declared that he was in favour of peace.
Asked to elaborate by the emperor, he criticised the impact of war on resources and the standard of living of those near the border.
Zhang Tang, when consulted on his opinion, dismissed Di Shan as a "stupid Confucianist" with no understanding of the matter.
Emperor Wu then asked Di Shan whether he could keep out the Xiongnu if made a governor of a province.
However, Di Shan finally relented when offered the position of commander of a guard post, afraid that he would be handed over for trial if he refused.