Background
The succession order in the Sunwu court following Sun Quan's assumption of the imperial title fell into crisis after Crown Prince Sun Deng died of illness in Chiwu 4 (241). Sun Deng was Sun Quan's eldest son and combined political ability with broad popular regard; his early death made the succession question suddenly and acutely complicated. Sun Quan installed his third son Sun He as crown prince and simultaneously created his fourth son Sun Ba as King of Lu, yet the honors, carriages, clothing, palaces, and retinues allocated to the two were treated as nearly equivalent — the phrase "twin palaces of equal standing" (ergong qiheng) derived from precisely this arrangement. In the eyes of the court ministers, this "minimal visible differentiation" was an extremely dangerous signal: it encouraged the King of Lu and his partisans to harbor designs on the heir's position, and it caused the supporters of the crown prince and the King of Lu to rapidly coalesce into two opposing factions within the court. Throughout roughly the middle and late Chiwu period (c. 242–250), the Sunwu court expended enormous political energy on the inner struggle known as the Ergongzhizheng. Gu Tan's memorial on the distinction between the legitimate heir and lesser sons was one of the most representative statements of the crown prince's faction in the early-to-middle phase of this struggle.
Key Figures
Gu Tan was the leading representative of the Gu clan of Wu commandery; his grandfather Gu Yong had served as Grand Counselor for twenty years before dying shortly before these events — "within a few months of Yong's death, [Gu Tan] was appointed Grand Chamberlain and deputized for Yong in the Secretariat" [c:18013] — and Gu Tan assumed the political capital accumulated by his father and grandfather as the new-generation core representative of the Gu lineage, holding real power in the Sunwu bureaucracy as both Grand Chamberlain and acting head of the Secretariat. The Gu clan had always treated Confucian ritual norms as its political stance, and its consistent insistence on the distinction between legitimate heir and lesser sons was a political conviction transmitted across generations. The ultimate addressee of the decision was Sun Quan himself, who was simultaneously the common father of both the crown prince and the King of Lu and the sole arbiter of this political crisis. The King of Lu, Sun Ba, was not named in Gu Tan's memorial, but he was the actual beneficiary of the "equal standing" arrangement and the real target Gu Tan sought to strike at.
The Core Issue
The central argument of Gu Tan's memorial was the "distinction between legitimate heir and lesser sons" — one of the most fundamental principles in classical Chinese political philosophy regarding the order of succession. From a ritual standpoint, the crown prince as heir apparent should have a clearly visible difference from the princes of the realm in ceremonial honors, treatment, residence, and the composition of his retinue; this difference was not merely a question of "lavish versus frugal" but the core guarantor of political order's stability. Gu Tan's position can be summarized in three points. First: the stability of the crown prince's position derives from the "self-evident quality" created by differential treatment — once the princes' circumstances approach those of the crown prince, the crown prince's superior status is no longer naturally beyond question. Second: the excessive favoritism shown to the King of Lu encourages speculative behavior among court ministers, who stand watching between the two princes, and the political cohesion of the court will be eroded. Third: Sun Quan's own security in his later years will depend on the clarity of the succession arrangement — the "equal standing" structure is equally harmful to the political stability of Sun Quan's own twilight reign. These three layers of argument form the logical skeleton of Gu Tan's memorial.
Political Consequences
In the short term, Gu Tan's memorial failed to achieve its purpose: Sun Quan's favoritism toward the King of Lu did not visibly diminish, and the "equal standing" arrangement continued. Partisans of the King of Lu — Quan Ji, Yang Zhu, Lv Ju, and others — intensified their political attacks on the crown prince's faction, while the crown prince's faction mounted a counterattack with the support of senior statesmen Lu Xun, Gu Tan, Zhang Xiu, and Zhu Ju. The struggle escalated in the latter Chiwu years into a large-scale political purge: Lu Xun died in grief and resentment; Gu Tan and Zhang Xiu were exiled to Jiaozhou; Zhu Ju was first sent to a peripheral post, then forced to commit suicide; neutral figures such as Teng Yin were caught up in the net as well. In the medium term, Sun Quan ultimately in Chiwu 13 (250) deposed Crown Prince Sun He and forced the King of Lu Sun Ba to commit suicide, installing the seven-year-old Sun Liang as crown prince — a "both sides lose" resolution that plunged the Sunwu regime into the successive dynastic turbulence of Sun Liang, Sun Xiu, and Sun Hao after Sun Quan's death. In the long term, the Ergongzhizheng was the political watershed that marked Sunwu's decline from strength: it consumed the political capital of the first generation of meritorious subjects (the Lu Xun and Gu Yong lineage) and the second generation of commanders (the Zhu Ju and Teng Yin lineage), leaving Sunwu without the internal cohesion needed to face the systematic political pressure of the Simashi. Gu Tan, as a core figure in the crown prince's faction, ultimately died in exile in Jiaozhi — his political prophecy (that the King of Lu's equal treatment would invite catastrophe) was vindicated point by point, yet he himself became one of the sacrificial victims of the very struggle he had tried to prevent. This case reminds later generations that at critical junctures in power structures, those who "spoke the truth early but were not heeded by the ruler" often bear the cost earliest and most completely.
Counterfactual Analysis
If Sun Quan had adopted Gu Tan's advice in the early Chiwu period and visibly reduced the ceremonial scale of the King of Lu's honors, the Ergongzhizheng might have been suppressed at the germinal stage and the political cohesion of the Sunwu regime might have been maintained for more than a decade longer. If Gu Tan had adopted a more diplomatically subtle strategy — for instance, offering private counsel rather than a formal memorial — he personally might have avoided being placed on the core target list of the crown prince's faction, but this approach could not have resolved the structural problem of the "equal standing" arrangement itself. If the King of Lu, Sun Ba, had at some point voluntarily stepped back — not unprecedented among princes in the San Guo period — the Ergongzhizheng might not have escalated to the point of political purging. At a deeper level, the root cause of the Ergongzhizheng lay not in the failure of Gu Tan or Lu Xun or their peers to "prevent it in time" but in Sun Quan's deliberate ambiguity about the succession arrangement in his later years — he may have hoped that by creating tension between the crown prince and the princes he could reinforce his own ultimate arbitrating authority. If this reading is correct, then no memorial could ever have fundamentally altered the dynamic, and the political tragedy of men like Gu Tan was fated from the very beginning. Gu Tan's memorial on the legitimate heir and lesser sons is therefore simultaneously a concrete event in Sunwu's political history and a representative specimen of the recurring narrative in Chinese classical autocracy: "the loyal official speaks early, the ruler grasps it late, and the state suffers the harm."