Background
The Dazhong farm-colonization of Jingyao year 5 (262) was the most tragically colored political-military decision of Shuhan's final years — simultaneously a strategic readjustment after Jiang Wei's nine failed Northern Expeditions and a vivid symptom of the collapse of Shuhan's political ecosystem. Externally, from Zhuge Liang's fifth Northern Expedition (234) through Jiang Wei's last (262), thirty years of repeated campaigns had drained Shuhan's national strength; the people were exhausted and the treasury depleted, while the Wei state, after Simashi solidified internal control, possessed national strength far surpassing Shuhan's. Internally, after Fei Yi and Dong Yun died in succession, Shuhan's court affairs fell under the domination of the eunuch Huang Hao, and Liu Chan grew increasingly absorbed in pleasures; the Right Grand General Yan Yu had allied with Huang Hao and was attempting to supplant Jiang Wei's military authority. Jiang Wei, holding supreme military command, could theoretically have deployed that military power to settle accounts with Huang Hao directly — but when in Jingyao year 5 he memorialized Liu Chan requesting the execution of Huang Hao, Liu Chan dismissed it with "Hao is merely a menial who scurries about; the late Director Dong Yun loathed him and I always resented that; why should you, my lord, trouble yourself over him?" — leaving Jiang Wei trapped in the double bind of "unable to purge the court, yet unable to tolerate the factional strife in the capital." Farm colonization at Dazhong was the "third path" found under these constraints.
Principal Figures
There were four groups of central parties to the event. The first is Jiang Wei — as the military successor designated by Zhuge Liang, he had directed Shuhan's Northern Expedition campaigns since Yanxi year 16 (253); by Jingyao year 5 he was sixty-one years old, having kept watch on the frontier for years with little influence over internal politics. The second is Xi Zheng — Shuhan's Secretariat Director and literary attendant, renowned for "wide reading and ability to read the times"; he presented Jiang Wei with the Dazhong farm-colonization strategy, which from a political calculation standpoint was a three-stage blueprint for Jiang Wei: "preserve yourself — avoid calamity — return to the offensive". Xi Zheng himself did not participate in court political struggles, but his advice directly shaped the military configuration of Shuhan's final year. The third is Liu Chan — as Shuhan's ruler, his role in the Dazhong affair was that of a "passive assenter"; during the Wei invasion he would display blind trust in a spirit-medium's divination and withhold Jiang Wei's urgent memorial without forwarding it. The fourth is Huang Hao — as a eunuch, his political objective was to remove Jiang Wei and replace him with Yan Yu; for him, Dazhong farm-colonization was a political victory: Jiang Wei had voluntarily stepped outside.
The Central Issue
At the surface level the issue was "military farm colonization"; at the deeper level it was an acute question about "the viability of an outer exile as a self-preservation strategy for a powerful minister" and "the boundary of the ruler's trust." Xi Zheng's plan had four layers of logic: to obtain ripened grain to supplement military provisions; to provide a basis for plotting the seizure of Longyou's commanderies; to prevent Wei forces from looking directly toward Hanzhong; and to protect the commander by keeping his troops at arm's length from the capital. The first three were military justifications; the fourth was the real political core. The elegance of this plan was its packaging of "self-preservation" as "active advance," allowing Jiang Wei to avoid a direct rupture with Huang Hao while not abandoning his Northern Expedition ideals — withdrawing from the political whirlpool of Chengdu under the posture of "accumulating strength through farm-colonization." But the plan's hidden cost was that Jiang Wei's distance from the center greatly diminished his influence over court affairs; if Wei launched a large-scale invasion of Shu, Jiang Wei's military power would be pinned in Longxi and unable to return to reinforce quickly. This tension between "self-preservation and loss of control" is the true source of the tragic dimension of Dazhong farm-colonization. From Xi Zheng's perspective, he provided "the optimal solution"; from the perspective of historical results, it proved to be "the second-best solution" — the cost of self-preservation far exceeded what was imagined.
Political Consequences
The most immediate consequence was that when Zhong Hui and Deng Ai invaded Shu in 263, Jiang Wei's military power was pinned at Dazhong: he was forced to maneuver against Deng Ai and Zhuge Xu along the Dazhong–Yinping corridor and could not return in time to reinforce critical defensive lines such as Hanzhong and Jiange. This "military misalignment" was one of the direct military causes of Shuhan's destruction. Looking deeper, Dazhong farm-colonization's political consequences included at least five dimensions. First, Jiang Wei's distance from Chengdu allowed the Huang Hao clique to take complete control of court affairs; Liu Chan's assessment of military intelligence came to depend entirely on a spirit medium and divination, and Shuhan's central decision-making mechanism collapsed. Second, the Hanzhong defensive arrangement Jiang Wei left behind — Hu Ji holding Hanshou, Wang Han holding Lecheng, Jiang Bin holding Hancheng, and Jiang Shu and Fu Qian holding the passes — was in principle reasonable, but lacked a unified chain of command; when Zhong Hui marched south, each position was broken separately. Third, Jiang Shu surrendered at Yangpingguan while Fu Qian died in battle; Jiang Wei's originally conceived "heavy-gate defense" system was broken from within. Fourth, Jiang Wei himself, though he held Zhong Hui at Jiange for several tens of days, was outflanked when Deng Ai made his surprise crossing of Yinping and struck directly at Chengdu, and Shuhan was destroyed. Fifth, Jiang Wei himself, after Shu's fall, joined Zhong Hui's rebellion against Wei, ultimately dying in the attempt — the last tragic military figure of Shuhan.
Counterfactual Analysis
The most imaginative counterfactual is: if Jiang Wei had not followed Xi Zheng's advice to farm-colonize at Dazhong but instead held troops in Hanzhong and memorialized a request to purge the court (even at the cost of direct confrontation with Huang Hao), Shuhan's central government might have remained within his sphere of influence. Even if he could not eliminate Huang Hao, he could at least ensure military intelligence was transmitted upward and court affairs would not be dominated by spirit-medium divination. Second, if Liu Chan had not believed the spirit medium's words but had immediately dispatched reinforcements per Jiang Wei's urgent memorial, the odds of Deng Ai's surprise crossing of Yinping would have fallen sharply — Shuhan's destruction could have been delayed by several years, waiting for the window of the Simashi clan's planned coup to displace Wei. A third scenario: if Xi Zheng's plan had been proposed and implemented in Jingyao year 3 (260) or even earlier, Jiang Wei would have had more time to consolidate Longxi, and he might genuinely have been able to nibble away at Longyou's commanderies and form a new strategic configuration of "using Longyou to constrain Wei" — but the precondition was that Huang Hao could not be allowed to grow dominant in Chengdu, and Liu Chan could not be allowed to completely lose control. The true tragedy of Dazhong farm-colonization lies not in the strategy itself but in "the timing being already too late" — when Shuhan's political functions had already been worn down to the point where no complex strategy could be carried, even the most brilliant plan could only become a catalyst accelerating collapse. Xi Zheng's golden counsel was, from the other side of history, a final prescription of "drinking poison to quench thirst."