Battle of Dongkou

Part of the wars of the Three Kingdoms period

Date	Autumn (ninth lunar month) of 222 - winter (11th lunar month) of 222
Location	Dongkou (洞口; present-day southern Jiangsu Province, opposite bank of Nanjing)
Result	Wu Pyrrhic victory; overall stalemate; Wei army retreats

Belligerents

Cao Wei

Kingdom of Wu

Commanders and leaders

Cao Xiu

Lü Fan

The Battle of Dongkou was a naval battle fought between late 222 and early 223 between forces of the state of Cao Wei and the Kingdom of Wu during the Three Kingdoms period of Chinese history. The battle concluded in a Wu Pyrrhic victory.

After the Shu emperor Liu Bei was defeated by Sun Quan's forces at the Battle of Xiaoting, Sun benefited from his submission to the Wei ruler Cao Pi; who would help Sun in the conflict against Liu Bei. However, on both sides of the two forces, this was never a popular concept, especially in the ranks of Sun Quan, who defeated Cao Cao at the Battle of Red Cliffs 14 years ago after resisting surrender. To make matters worse, Cao Pi and his officers were uneasy about Sun's titles and ranks (such as King of Wu) because it was quite inappropriate since they were considered a vassal state under Wei. It was even considered within Sun Quan's forces that the alliance with Wei was futile, because the defeat they caused Liu Bei at Xiaoting was so critical that it meant that their alliance with Wei was no longer an asset for survival. Sun Quan also appeared as if he was planning to have this alliance go not much longer than it was supposed to.

In a matter of time, Cao Pi's plan to keep Sun Quan and Shu's relations sour backfired as Sun Quan and Liu Bei rekindled their alliance. In an attempt to improve his own relations with the Sun clan, he demanded Sun Deng (Sun Quan's eldest son) to be sent to the Wei capital Luoyang as a hostage. However Sun Quan declined this request, and later apologised to Cao Pi, stating his son was still very young and vulnerable in his health to be away from his home and family. Cao Pi did not bring up or press the matter. However Cao Pi demanded Sun Deng as hostage soon again. This was also declined.

Diplomatic ties between the two continued to sour until finally, Cao Pi would attack Sun Quan. Sun Quan would repetitively send envoys to negotiate peace between the two, but resulted in failure. Soon after, Sun Quan would proceed into declaring independence in November 222.

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