Strategic Background
The situation in the third year of the Huangwu era was not favorable to Eastern Wu. Cao Pi had declared himself emperor three years earlier, and his three southern campaigns had a clear aim: to use sustained military pressure to force Jiangdong back into a posture of submission. This campaign was the largest of the three: more than three hundred thousand troops on land and water, Cao Pi himself riding his dragon boat, advancing from the Cai and Ying rivers into the Huai, targeting Guangling. Eastern Wu's window for response was extremely narrow: Lu Xun was holding Jingzhou and could not be easily moved, and the Wu heartland lacked a field army capable of matching Cao Pi's scale — a head-on clash would inevitably end badly. Under these circumstances, Sun Quan's selection of Xu Sheng as front-line commander was not because he was Wu's most senior general, but because he had already demonstrated in several Huainan defensive engagements a tactical style of "winning big from small, prevailing through ingenuity."
Deployments
Cao Pi's side employed a classic large-formation, combined water-and-land advance: the dragon boat as flagship, the navy moving through the Huai River–Yangtze corridor, the land forces advancing along the bank, with more than three hundred thousand troops relying primarily on "psychological intimidation plus material attrition" to pressure Eastern Wu into concessions. Xu Sheng's side was a precisely calculated deployment of "key-point fortification plus psychological deception": rather than dispersing his forces across every crossing along the Yangtze, he concentrated on the critical nodes from Jianye to Nanxu (modern Zhenjiang), while directing massive manpower into a "display construction project" — straw bundles shaped into human forms, banners planted everywhere, and a continuous line of illusory fortress towers erected through the night. This "light on troops, heavy on visuals" deployment placed psychological warfare first among tactical priorities, betting that Cao Pi, unfamiliar with the terrain south of the Yangtze, would overestimate the size of the defending force.
Key Decision Points
Xu Sheng made at least three key decisions in this campaign. The first was his refusal of the "cross the river and engage" plan proposed by his nephew Sun Shao. Sun Shao argued they should strike before Cao Pi had finished crossing, but Xu Sheng judged this reckless — Cao Pi had overwhelming numbers and naval superiority; crossing the river to meet him would only consume Wu's precious mobile forces. The second was that even after Sun Quan personally intervened to spare Sun Shao, Xu Sheng still insisted on the principle of military law, requiring Sun Shao to bear responsibility for his insubordination, so as not to have the commander's authority undermined. The third was the timing of the illusory fortress construction: choosing to work through the night before a predicted heavy fog, ensuring that the moment the fog lifted the following day the Wei forces would see a defensive line that appeared fully and suddenly formed. Of these three decisions, the third was technical; the first two were commander-level judgments — Xu Sheng had to simultaneously manage external pressure from Cao Pi's army and internal pressure from Sun Shao's impulsiveness. His "dual-front management capacity" far surpasses the illusory fortresses themselves as the true achievement deserving of praise.
Outcome and Resonance
The campaign ended with Cao Pi voluntarily withdrawing his forces. His exclamation that "the men and resources of Jiangnan are beyond my reach" marks the moment when Caowei's psychological advantage over Jiangdong was significantly reduced. In the short term, this defensive success bought Eastern Wu at least a decade of stability on its northern front, allowing Sun Quan to focus on internal administration and the rebuilding of the alliance with Shuhan. In the long term, it established Wu's fundamental defensive philosophy against the north — no decisive battle north of the Yangtze, no hard fighting along the bank, but rather a combination of the Jiangnan waterway network and psychological warfare to force the northern armies to withdraw when they found the way too difficult. Xu Sheng's personal standing as a general also leapt upward as a result, elevating him from a mid-ranking field commander to one of Eastern Wu's principal military figures. Another hidden consequence of this campaign was a shift in Sun Shao's political position: having been suppressed by Xu Sheng's insistence on military law, he then actually won distinction by "privately crossing the river on his own initiative," forcing Sun Quan afterward to rebalance military discipline against clan sentiment.
Counterfactual Analysis
Had Xu Sheng accepted Sun Shao's plan to cross the river and engage, Wu's forward forces would have been encircled by three hundred thousand Wei troops in Huainan, nearly certainly resulting in defeat. Cao Pi would have used this as leverage to force Sun Quan to cede territory and submit as a vassal, and the Wu-Shu alliance might well have collapsed as a result. Had Xu Sheng chosen not to construct the illusory fortresses and simply held Jianye in a pure defensive posture, Cao Pi — without the psychological pressure he encountered — would very likely have continued advancing toward the northern bank of the Yangtze in search of a crossing point, and the campaign would have dragged into a prolonged war of attrition lasting months. Wu's navy had the advantage, but it would still have suffered losses. Xu Sheng's greatest strategic insight was his recognition that Cao Pi's personal command of this campaign was itself imbued with strong elements of political theater: what Cao Pi needed was not to actually reach Jianye, but to bring home a narrative of "distinguished southern campaign." Xu Sheng therefore gave Cao Pi a face-saving exit — "Jiangnan is beyond reach; withdrawing upon recognizing the difficulty is itself wisdom" — that protected Eastern Wu while not leaving Cao Pi looking utterly routed. This capacity to integrate the psychology of war into tactical design is the aspect of Xu Sheng's campaign that modern historical commentary most admires. Historiographically, the specific details of this "illusory fortress" operation are relatively sparse in the official histories; the novel's expansion is primarily in visual description, but the core account — "Xu Sheng defends the Yangtze, Cao Pi withdraws north" — has basis in the official record and is not pure invention.