Xiahou Mao, courtesy name Zilin (子林), was a military general and civilian administrator of Cao Wei during the Three Kingdoms period of Chinese history. He was the second son of Xiahou Dun. He was given the title "Marquis of the Imperial Domain" (列侯) and was married to Cao Cao's daughter Princess Qinghe.
Xiahou Mao was a close friend of Cao Pi, and after Cao Pi became emperor, he named Xiahou Mao as "General who Stabilizes the West" (安西将军), succeeding his father to take charge of Guanzhong, stationed in Chang'an (present day Xi'an). In terms of military talent, Xiahou Mao was alleged to be far from his capable father, and according to Weilüe, these allegations of incompetence even reached Shu Han, where the general Wei Yan sought to exploit Xiahou Mao's incompetence by sending an unexpected army across difficult terrain. The plan was rejected by Zhuge Liang.
In 228, Cao Rui personally led reinforcement to strengthen the local defense against Zhuge Liang's Northern Expeditions, and removed Xiahou Mao from his command and reassigned him to a civilian job in the imperial court as Imperial Secretariat (尚书). However, Xiahou Mao became slandered by his own wife and younger brothers: Xiahou Dun's third and fourth sons Xiahou Zizang (夏侯子臧) and Xiahou Zijiang (夏侯子江).
Xiahou Mao's younger brothers had constantly misbehaved and abused their powers, and Xiahou Mao disciplined them repeatedly. The younger brothers hated Xiahou Mao for disciplining them and plotted against him by accusing Xiahou Mao of slandering. The younger brothers found an ally, their sister-in-law, Princess Qinghe, who was extremely jealous and upset that Xiahou Mao was keeping numerous concubines and found the opportunity to retaliate by joining her younger brothers-in-law. As a result, Xiahou Mao was arrested and was to be executed by Cao Rui. Xiahou Mao was saved when a military official in the imperial court, Duan Mo (段默), requested Cao Rui to investigate the matter further because it was extremely unlike for Xiahou Mao to commit such a serious crime. Cao Rui listened and indeed, investigation revealed that the charges were false. As a result, Xiahou Mao was released from jail and he reassumed the post of Imperial Secretariat.
Xiahou Mao's supposed impotence was dramatized in Luo Guanzhong's historical novel Romance of the Three Kingdoms. When he was assigned to defend the Wei-Shu border, he was not well respected by his colleagues, who assumed that Xiahou Mao would be unable to fulfil his role. Xiahou Mao reportedly responded to such criticism as follows:
Ever since I was a boy, I have studied strategy, and I am well acquainted with army matters. Why do you despise my youth? Unless I capture this Zhuge Liang, I pledge myself never again to see the Emperor's face."
His early encounter against Shu turned out badly, and he was forced to flee. After consulting with his generals, he planned a successful ambush against famed Shu general Zhao Yun and fought a fifty pass duel against him. Unfortunately for Mao, this victory was only temporary, as Shu generals Zhang Bao and Guan Xing both arrived with ten thousand troops to save Zhao Yun; Xiahou Mao's army was utterly routed by nightfall. Mao escaped to the city of Nan'an with just one hundred horsemen. He managed to resist a siege for ten days until Zhuge Liang arrived and directed his efforts towards another city, Tianshui. A defeated Wei general named Cui Liang, who was en route to Tianshui, offered Zhuge Liang to convince the governor of Nan'an, Yang Ling, to turn the city over. In fact, he had no such intention, instead telling Yang Ling what had taken place, and the two of them and Xiahou Mao attempted to lure the Shu army into the city and massacre them.
Zhuge Liang saw through the plot, however, and both Cui Liang and Yang Ling were slain by Zhang Bao and Guan Xing, respectively, and Xiahou Mao was captured. He begged for his life and was released by Zhuge Liang on condition he convinced Jiang Wei to defect to Shu. In fact, Xiahou Mao was simply being played a fool, and was tricked into thinking that Jiang Wei had already defected. He went to Tianshui to meet the defender there, Ma Zun, and his false belief of Jiang Wei's defection was reinforced when a fake Jiang Wei led an attack upon the city. He was driven off, and so was the real Jiang Wei when he came to Tianshui later. Due to the later defection of Jiang Wei and the betrayal of Yin Shang and Liang Xu (friends of Jiang Wei), the city fell. Xiahou Mao fled with a few hundred loyalists and sought refuge with the Qiang tribe, and, staying true to his words, never returned.