Zhang Song’s mission to Liu Bei begins as an attempt to secure Cao Cao’s help for Liu Zhang, ruler of Yizhou, but ends by redirecting that political appeal to Xuande. After Cao Cao dismisses him and treats his candid criticism as an affront, Zhang Song turns to Xuande, whom he regards as a benevolent alternative. He brings secret maps of Shu and proposes that Xuande take the region; what begins as an envoy’s journey thus becomes the opening move in Xuande’s acquisition of Yizhou.

The mission to Xuchang

Liu Zhang’s court sends Zhang Song north with gifts intended to win Cao Cao’s support against Zhang Lu, whose power threatens Shu. Zhang Song also carries maps of Shu that he has gathered secretly. Spies report his journey to Kong Ming, who sends agents to follow developments, so the mission is watched from the outset by the very rival whose position it will eventually strengthen.

In Xuchang, Zhang Song waits day after day for an audience. Only after bribing Cao Cao’s servants does he gain access. Cao Cao immediately asks why Liu Zhang has not sent tribute for years. Zhang Song attributes the failure to unsafe roads, but Cao Cao insists that he has made the country secure. Zhang Song answers by naming the forces that make the claim untenable: Sun Quan to the south, Zhang Lu to the north, and Xuande to the west, each with more than a hundred thousand men. His response challenges Cao Cao’s picture of an ordered realm rather than offering the deferential reassurance expected of an envoy.

Cao Cao already dislikes Zhang Song’s appearance, and the bluntness of his answer deepens that hostility. Cao Cao leaves without further discussion. When servants rebuke Zhang Song for his conduct, he replies that people from Shu do not bend and scrape. Yang Xiu, Cao Cao’s first secretary, hears the exchange and, intrigued by the visitor, invites him to talk in his library. The failed audience has nevertheless created a new opening: Zhang Song’s candor earns the attention of someone inside Cao Cao’s court.

The contest over learning and authority

Yang Xiu asks Zhang Song about Shu. Zhang Song describes a region difficult to reach by either river or road, yet productive and rich in capable people. He praises its educated court and its local figures of distinction, then challenges Yang Xiu’s apparently modest official role. When Yang Xiu defends his responsibilities for the army’s welfare, Zhang Song argues that Cao Cao knows little of classical teaching or military strategy and cares chiefly about his own advancement.

To answer the insult, Yang Xiu produces The New Treatise of Meng De, presenting it as Cao Cao’s own work based on Sun Zi’s military writing. Zhang Song reads its thirteen chapters at a glance, dismisses them as material already familiar to Shu’s children, and identifies the text as an old work from the Warring States period. Challenged to demonstrate his claim, he recites the text word for word after a single reading. His memory turns a meeting about Shu’s resources into a public test of Cao Cao’s intellectual reputation.

Yang Xiu is impressed and offers to intercede. When he reports Zhang Song’s feat to Cao Cao, Cao Cao wonders whether his own writing may have accorded with older wisdom, then orders the book destroyed. He agrees, however, to meet the envoy the following day while inspecting the troops. The episode leaves Zhang Song with access to Cao Cao but no reason to expect that access will lead to cooperation.

The break with Cao Cao

At the troop inspection, Zhang Song sees the scale and display of Cao Cao’s military force. Asked whether Shu has anything comparable, he answers that it does not, because Shu rules through benevolence and justice. Cao Cao, stung by the rebuke, boasts of his victories. Zhang Song counters by recalling Cao Cao’s defeat at Red Cliffs, his escape at Tong Pass, and his flight from archers at the River Wei.

Cao Cao becomes so angry that he orders Zhang Song’s execution. Yang Xiu stops him by pointing out that Zhang is an emissary from another state, but Cao Cao expels him from the palace. The contrast between the two rulers is now explicit: Cao Cao’s military splendor cannot persuade Zhang Song to support him, while Cao Cao’s reaction to criticism confirms Zhang Song’s judgment that he cannot work with worthy or capable people. The mission’s original purpose—securing Cao Cao’s assistance—has failed.

From rejected envoy to advocate for Xuande

As he packs to leave, Zhang Song decides that he has one remaining course: to visit Xuande. He has heard of Xuande’s benevolence and justice and is drawn by the prospect of a ruler unlike Cao Cao. Crossing into Xuande’s territory, he is met by Zhao Zilong and an official escort of five hundred cavalry. At his lodging, a hundred men are assembled to welcome him; Guan Yu arrives in person and has arranged a banquet in his honor.

The next day, Zhang Song and Guan Yu ride to meet Xuande. Xuande, Kong Ming, and Pang Tong dismount to greet the visitor. At the banquet they discuss how precarious Xuande’s position in Jingzhou is, including Sun Quan’s demands for the territory’s return. Zhang Song invokes Xuande’s imperial lineage and asks whether he might one day ascend the throne as a legitimate heir. Xuande does not take up the suggestion. The conversation nevertheless establishes the political ground on which Zhang Song will make his more direct appeal: Xuande’s lineage and reputation offer an alternative claim to leadership.

Three days later, as Zhang Song is preparing to depart, he speaks plainly about Liu Zhang. He describes him as weak and unable to employ the wise and capable members of his court, while Zhang Lu threatens Yizhou from the north and its people long for better rule. Zhang Song says he went to Cao Cao for help but found him a traitor, unwilling to work with worthy people. He therefore urges Xuande to take Shu: Xuande should initially give the appearance of moving against Hanzhong, then seize the whole region. Zhang Song promises to assist and argues that success would secure Xuande’s place in history.

Xuande resists on the ground that Liu Zhang belongs to the same imperial family, and he points to Shu’s difficult roads and impassable mountains as further obstacles. Zhang Song answers the practical objection by producing the maps he secretly collected before leaving Yizhou. They show Xuande how to enter the region, and Zhang Song assures him that allies within Shu will support him. Xuande promises a reward if the hills remain green and the rivers flow; Zhang Song declines payment, explaining that meeting a wise and benevolent lord was reason enough to help. The maps convert a political recommendation into a practicable route of intervention.

The proposal becomes an invitation

Back in Yizhou, Zhang Song shares his plan with Fa Zheng and Meng Da, who agree. They arrange for Liu Zhang to send them as envoys to Jingzhou. Zhang Song then reports that Cao Cao is ambitious and dangerous, and recommends asking Xuande—a virtuous kinsman—for help against both Cao Cao and Zhang Lu. Liu Zhang accepts the advice and agrees to send Fa Zheng and Meng Da, despite other advisers’ pleas and their fear that Xuande will eventually overrun the country.

Fa Zheng carries Liu Zhang’s formal request for help against Zhang Lu to Xuande’s court. Xuande again says that he finds it difficult to contemplate attacking a member of his own imperial family. Fa Zheng counters that Liu Zhang has natural advantages but cannot govern, and that if Xuande does not intervene someone else will take the land. His argument calms Xuande’s hesitation. Thus the mission’s consequence is not simply Zhang Song’s personal defection: his private counsel brings an official appeal from Liu Zhang, giving Xuande a route into Yizhou under the stated purpose of aiding his kinsman.

The episode turns on a reversal of diplomatic direction. Zhang Song leaves Yizhou carrying gifts and maps for a mission meant to enlist Cao Cao; after Cao Cao’s dismissive conduct and anger, he redirects his allegiance and the maps to Xuande. The same geography that first appears as a barrier—difficult roads and mountains—becomes navigable through Zhang Song’s knowledge and inside support. His journey therefore links personal judgment, political persuasion, and territorial opportunity: the failed embassy to Xuchang becomes the beginning of Xuande’s campaign to take Shu.