Formation of the Sun–Liu alliance against Cao Cao

The Formation of the Sun–Liu alliance against Cao Cao is a turning point in the novel’s political and military balance: as Cao Cao’s forces approach the south, Xuande and Sun Quan move from separate calculations toward a common resistance. The alliance emerges not from settled trust but through competing arguments, deliberate tests, and the recognition that neither ruler can safely face Cao Cao alone. Its formation also establishes the prospect of a three-part balance among the north, Jingzhou, and the south.

Causes and strategic stakes

Cao Cao’s advance into Jingzhou brings his power directly to the borders of Sun Quan’s domain and alarms the advisers at Wu’s headquarters. Sun Quan’s immediate concern is not abstract: a conquest of Jingzhou places Cao Cao near the south, while Xuande’s forces are also threatened. Lu Su is therefore sent to propose an alliance with Xuande. At the same time, Kong Ming is advising Xuande to pursue the same partnership, reasoning that Cao Cao’s presence at Wu’s border may lead Sun Quan to seek his help. The shared danger makes cooperation possible, though each side must still consider what it stands to gain and whether the other can contribute enough to the struggle.

Kong Ming recommends that Xuande avoid stating plainly either the full scale of Cao Cao’s strength or whether the alliance serves Xuande’s interests. This guarded approach shapes the negotiations from the outset. Lu Su arrives with an offer, but Kong Ming’s advice keeps the terms from appearing to be a simple appeal for rescue. The alliance is instead presented as a calculation between powers whose interests overlap in opposing Cao Cao.

Negotiation and the test of Sun Quan

At Chaisang, Sun Quan is weighing Cao Cao’s formal letter, which urges him to join an attack on Xuande. Zhang Zhao supports accepting Cao Cao’s offer, while Lu Su argues against it. Sun Quan initially keeps his judgment to himself; in private, however, he asks Lu Su’s view and learns that Kong Ming has accompanied him. Sun Quan is surprised and pleased by Kong Ming’s presence, but the larger question remains whether resistance is realistic.

When Kong Ming is brought before Sun Quan’s advisers, they challenge the strength and judgment of Xuande’s side. Later, in private, Sun Quan asks how large Cao Cao’s army really is. Kong Ming answers that its cavalry, infantry, and naval forces together number well over a million, then estimates the total at nearer one and a half million. His account alarms Sun Quan and frustrates Lu Su, who had expected Kong Ming to avoid emphasizing Cao Cao’s strength. Kong Ming argues that Cao Cao is coming south to conquer it, and that accepting an alliance with him would amount to surrender. He withholds his proposed counterstrategy on the ground that Sun Quan has not asked him for it.

Lu Su carries this point back to Sun Quan, who is initially angry with Kong Ming but eventually agrees to hear him. Their conversation then turns from the size of Cao Cao’s army to its limitations. Sun Quan recalls that several earlier opponents of Cao Cao—Lü Bu, Liu Biao, Yuan Shao, and Yuan Shu—are dead, leaving Xuande as the only other leader positioned to challenge him; he doubts Xuande can withstand Cao Cao after so many setbacks. Kong Ming responds that Guan Yu still commands ten thousand men and Liu Qi has roughly as many. Cao Cao’s troops, by contrast, have travelled far, lack experience in naval warfare, and include conscripts with little commitment to their cause. Cooperation with Xuande, Kong Ming argues, could further weaken their morale and produce a three-legged balance of power among the north, Jingzhou, and the south. Sun Quan’s doubts briefly give way, and he agrees to join Xuande against Cao Cao.

Zhou Yu and the decision for war

Sun Quan’s agreement does not end the uncertainty. His advisers, led by Zhang Zhao, argue furiously that war would be disastrous, and Sun Quan again hesitates. He consults the counsel associated with his late brother Sun Ce: Zhang Zhao should advise him on domestic affairs, but Zhou Yu on external affairs. Zhou Yu is summoned from the Poyang lakes, where he is conducting naval exercises.

Zhou Yu first appears to shift with each delegation that comes to urge surrender or resistance. When Kong Ming and Lu Su meet him, he announces that he will recommend surrender to Cao Cao, reasoning that Cao Cao represents the Son of Heaven and that war could bring disaster to the south’s population. Lu Su protests that surrender would betray the rule established by three generations of Sun leaders. Kong Ming watches their exchange, then claims that Cao Cao’s enormous army could be made to withdraw if a single person delivered two people to him. He identifies the two as the Qiao sisters and invokes Cao Cao’s plans for the Bronze Bird Tower and the Bronze Bird Tower Poem as evidence of his supposed desire for them. The claim turns the debate into a personal provocation: Zhou Yu becomes furious and says he had only been pretending to support surrender, and that he will recommend action to Sun Quan.

Before Sun Quan’s assembled officials, Zhou Yu sets out a military case against Cao Cao. He argues that Cao Cao has advanced while his northern flank remains vulnerable, shifted from land warfare to a naval campaign his troops do not understand, moved south in winter when forage will be scarce, and taken his army into unfamiliar territory where disease is a danger. Against these disadvantages, Zhou Yu asks for 150,000 experienced soldiers and promises to defeat Cao Cao. Sun Quan rises with his sword and appoints Zhou Yu commander, with Cheng Pu and Lu Su as his deputies.

Commitment and significance

Even after giving Zhou Yu command, Sun Quan remains anxious, as Kong Ming warns. Zhou Yu returns to address him again, estimating that Cao Cao’s own northern troops number around 150,000 and are exhausted, while roughly 80,000 former followers of Yuan Shao have been forcibly conscripted and lack loyalty to Cao Cao. Zhou Yu says he can defeat them with 50,000 men. Sun Quan then declares that he is no longer afraid and that the battle may begin, adding that he will face Cao Cao himself if necessary.

The decision binds Sun Quan’s forces to Xuande’s resistance, but it does not erase the rivalry within the coalition. Zhou Yu is troubled by Kong Ming’s ability to read both strategy and Sun Quan’s uncertainty; he considers how to remove Kong Ming, then accepts Lu Su’s advice not to pursue that course while Cao Cao remains the immediate threat. The alliance is thus both a practical answer to Cao Cao’s advance and a temporary alignment among leaders who continue to assess one another. Its importance lies in converting separate fears into coordinated resistance and making the south, Jingzhou, and the north appear as the possible three supports of a divided political order.