Background
As a modern political historian looking back at Jianye in 258, this deposition-and-enthronement was in essence a textbook instance of the cycle that characterized late Eastern Wu: "strongman autocracy — imperial counteraction — strongman strikes again." Sun Jun and Sun Liang's brothers had held Eastern Wu's military and political power continuously for more than six years since the coup against Zhuge Ke; their legitimacy rested on a narrative of "purging those who threatened the throne." But Sun Liang had grown to sixteen, increasingly resentful of his long-standing exclusion from actual authority, and began secretly conspiring with Princess Luban and Grand Master of Ceremonies Quan Shang to eliminate Sun Liang; when the plot was leaked to Sun Liang through Quan Shang's daughter — Sun Liang's own consort — inside the palace, Sun Liang was forced to act preemptively [c:16770].
Key Figures
The mastermind of this deposition-and-enthronement was Grand General Sun Liang. His strategy was "depose first, then enthrone" — demote Sun Liang to Prince of Huiji and exile him from Jianye; simultaneously select an ostensibly mild, politically rootless adult member of the imperial clan to fill the throne. The chosen candidate was Prince of Langye, Sun Xiu. Sun Xiu was Sun Quan's sixth son, who had long resided in remote regions far from the centers of power such as Hulin and Danyang Commandery, and had even been harassed by Danyang Administrator Li Heng to the point of submitting a memorial requesting transfer to Huiji [c:16770]. This record led Sun Liang to judge him "easy to control." But Sun Xiu's true character was far more complex than Sun Liang anticipated: from the age of thirteen he had studied classical histories under Court Gentleman She Ci and Senior Official Sheng Chong, and had a deep understanding of politics. Sun Kai and Dong Chao, serving as the envoys sent to receive him, took on the tasks of explanation, persuasion, and escort, with Sun Kai simultaneously providing a legitimacy endorsement in his capacity as Zongzheng (Superintendent of the Imperial Clan) [c:16770].
Core Issues
Three key issues underlay this deposition-and-enthronement. The first is the question of legitimacy: Sun Liang employed a compound ritual of "Zongzheng reception, three declining of the seal, and a collective prostration of officials," making the deposition-and-enthronement procedure appear fully compliant with ritual propriety — Sun Xiu declined the seal three times in the eastern side-chamber of the informal hall of audience, and mounted the throne only after the officials had implored him three times; this degree of ritual elaborateness was exceedingly rare in a period of turmoil [c:16770]. The second is Sun Xiu's own attitude: at Qua, an elderly man named Gan Xiu kowtowed and urged him to "travel swiftly lest prolonged delay invite change." Sun Xiu listened and immediately accelerated his journey to the capital — showing a clear-eyed understanding that Sun Liang might have second thoughts [c:16770][c:16771]. The third is the distribution of power following enthronement: Sun Xiu enfeoffed Sun Liang as Chancellor and Governorship of Jing Province, creating five marquisates for the Sun Liang lineage and giving them command of the palace guard. This arrangement was outwardly deferential but in fact dangerous; yet it also bought Sun Xiu a window of time to calmly arrange his counteraction.
Political Consequences
The immediate consequence of this deposition-and-enthronement was Sun Liang's demotion to Prince of Huiji and his exile from Jianye, with Sun Xiu ascending to the throne and changing the era name to Yong'an. In the short term Eastern Wu exhibited a strange stability: the strongman Sun Liang believed he had accomplished his great work, while Emperor Sun Xiu responded with ritual courtesy and apparent submission. But Sun Xiu was not passively accepting the situation — he immediately began planning his counteraction in secret with Left General Zhang Bu and veteran commander Ding Feng. That same twelfth month came the famous Layue banquet counterattack against Sun Liang (see Event 167). Looking further ahead, this deposition-and-enthronement simultaneously planted two major foreshadowings: first, Sun Hao was enfeoffed as Marquis of Wucheng, which was the starting point of his eligibility for the throne [c:16771]; second, although Sun Xiu's restoration succeeded, he failed to reform the succession system, so that when he died prematurely in 264 the vacancy again emerged, enabling the tragedy of Puyang Xing and others promoting Sun Hao.
Counterfactual Analysis
Suppose Sun Liang had chosen not Sun Xiu but some other member of the imperial clan — an older candidate or someone more deeply embedded in the clan's political networks, such as one of Sun Xiu's elder-generation relatives — then these individuals might not have possessed Sun Xiu's capacity for patient endurance and precise counteraction, and Sun Liang might have continued to exercise autocratic power for several more years; but Eastern Wu's political situation would also have remained trapped in the strongman cycle for a correspondingly longer period. Alternatively, suppose Sun Liang's conspiracy against Sun Liang had not been betrayed by his consort and had succeeded as planned in 258 — then there would have been no need for Sun Xiu to appear at all, Sun Liang would have governed directly, and the succession order of Eastern Wu might have been more normal. Yet the actual path history took was: Sun Liang's conspiracy failed, Sun Xiu was enthroned, Sun Xiu counterattacked and killed Sun Liang, Sun Xiu died prematurely, Sun Hao acceded, and Eastern Wu perished — a chain of events like a row of dominoes, with the 258 deposition-and-enthronement as one of its pivotal tiles. Viewed from a macro perspective, this deposition-and-enthronement reveals the core pathology of late Eastern Wu's politics: institutions could not determine succession; only the temporary compromises of a few powerful individuals could do so, and with each compromise the regime drifted further from any stable equilibrium.