Background
The reconstruction of this alliance spanned the full six years from 223 to 229 and can only be seen clearly when broken into three phases. The first phase covers 221–222: Liu Bei invades Wu, suffers crushing defeat at Yiling, and entrusts his dying wishes at Baidituogu. Although Sun Quan won an unambiguous military victory, he clearly recognized that frontally destroying Shuhan would simply hand Cao Pi the profit; he therefore dispatched envoys to Baidicheng with condolences immediately after the war, leaving room for a future alliance. The second phase, 223–227, is a "period of cautious contact": after Liu Bei's death Zhuge Liang took charge of Shuhan; in his "Letter to Sun Quan" he emphasized the strategic consensus of "Han and Wu as one family." Sun Quan sent Deng Zhi and Zhang Wen as envoys; both sides gradually restored formal diplomatic relations, though this remained mutual probing rather than genuine joint action. The third phase is anchored in 228, when Lu Xun's great victory over Cao Xiu at Shiting provided Eastern Wu with capital to display externally. Lu Xun proactively counseled Sun Quan to write to Sichuan and invite Zhuge Liang to coordinate a northern campaign; from this point the alliance truly entered a phase of practical operational coordination.
Principal Figures
Sun Quan played the role of "realist sovereign" throughout the alliance's restoration: he wished both to use Shuhan to pin down Caowei and to avoid being drawn by Zhuge Liang into an attritional war. Lu Xun was the practical architect of the alliance — after winning at Shiting he did not press northward but instead maximized the diplomatic value of the victory by writing to Sichuan and inviting Zhuge Liang to act together. This reflects his clear-headed understanding of Wu's strategic position: Jiangdong's military strength was insufficient to overturn the balance alone; the alliance had to be maintained to preserve strategic equilibrium. Zhuge Liang was the alliance's greatest beneficiary. He had "a strong army with plentiful provisions and fodder" at Hanzhong and was preparing to march north; the Wu envoy's letter arrived precisely when it provided strategic cover for his northern campaign plans. He thereafter repeatedly sent Fei Yi to Wu carrying letters, making the Wu-Shu alliance a standing pillar of Shuhan's strategy. In the novel's narrative, Liu Chan appears only as a delighted "receiver," but at the institutional level his endorsement of the alliance spared the Wu-Shu relationship the risk — such as Liu Bei's invasion of Wu — of a single sovereign rewriting state policy on his own.
Core Issues
The reconstruction of this alliance has three core issues. The first is "how to transcend the hatred of Yiling." The Battle of Yiling cost Shuhan two generations of military-political backbone in Guan Yu and Zhang Fei, and national and personal grievances ran extremely deep; for such a pair of states to form a new alliance required a statesman capable of placing "national interest" above "sovereign revenge" — precisely the role Zhuge Liang assumed after the Baidituogu. The second is "making the alliance operational." The earlier Liu-Sun alliance at Chibi and in the Hanzhong phase had always been ad hoc and verbal; after 228, Wu and Shu moved through written correspondence, mutual intelligence-sharing, and even the 229 "divide the realm between us" oath toward institutionalization. The third is "how to handle the question of imperial proclamation." In 229 Sun Quan formally declared himself emperor, shattering the legal framework of "legitimate succession to the Han house" that both parties had nominally maintained. Shuhan could have used this to break relations; instead Zhuge Liang pressed political rationality over moral objection and sent Fei Yi to Wu to offer congratulations and sign a formal treaty, elevating the relationship from "morally grudging" to "geographically stable."
Political Consequences
The most direct result was that Wu and Shu fought no major battles for the next thirty years, and the strategic configuration of the western Jianghan axis, the northern Huainan axis, and the eastern Yangzhou axis was essentially fixed — Caowei was perpetually dividing its forces between two fronts. Next came a division of labor: Zhuge Liang used Hanzhong as base to campaign year after year toward Qishan, while Sun Quan repeatedly threatened the Hefeixincheng axis and the Xiangyang axis, ensuring Caowei could never concentrate forces to eliminate either adversary. Third were cultural and institutional effects: Zhuge Liang's "make peace in the east with Sun Quan" strategy was wholly inherited by Jiang Wei; Wu-Shu diplomatic exchanges continued all the way to the eve of Shuhanmiewang in 263, and even after Deng Ai's crossing of Yinping and Liu Chan's surrender, Sun Xiu still attempted to dispatch troops to aid Shu — demonstrating the resilience this alliance had built.
Counterfactual Analysis
Had the Battle of Shiting not occurred in 228 and Lu Xun lacked a military achievement to display to Sichuan, the Wu-Shu relationship might have remained at the level of polite contact in the style of Deng Zhi and Zhang Wen, never entering practical operational coordination. In that case, when Zhuge Liang launched his first Qishan campaign he would have borne the full weight of Caowei's main force alone; the pace of the northern campaigns would have been forced to slow, and Shuhan's consumption of national strength would actually have been more severe. Conversely, had Zhuge Liang in 229 rejected Sunquanchengdi out of "legitimate Han succession" considerations and refused recognition, the two states would have immediately entered a cold war; Caowei would have been the great beneficiary of that rupture, and the Wu-Shu balance might have collapsed in the 230s. From this angle, Zhuge Liang's political-rational acceptance of Sun Quan's imperial proclamation was the most critical step of the entire alliance-reconstruction — a step that converted ethical conflict into geopolitical cooperation and allowed the San Guo stalemate to endure until 263.