Liu Heng was a son of Emperor Gao of Han and Consort Bo, later empress dowager. When Emperor Gao of Han suppressed the rebellion of Dai, he created Liu Heng Prince of Dai.
After Empress Dowager Lü's death, the officials eliminated the powerful Lü clan, and deliberately chose the Prince of Dai as the emperor, since his mother, Consort Bo, had no powerful relatives, and her family was known for its humility and thoughtfulness. His reign brought a much needed political stability that laid the groundwork for prosperity under his grandson Emperor Wu. According to historians, Emperor Wen trusted and consulted with ministers on state affairs; under the influence of his Taoist wife, Empress Dou, the emperor also sought to avoid wasteful expenditures.
Historians noted that the tax rates were at a ratio of "1 out of 30" and "1 out of 60", corresponding to 3.33% and 1.67%, respectively. (These rates are not for income taxes, but property taxes, as the only ancient Chinese attempt to levy an income tax would come in the time of Wang Mang.) Warehouses were so full of grain, that some of it was left to decay.
In a move of lasting importance in 165 BC, Emperor Wen introduced recruitment to the civil service through examinations. Previously, potential officials never sat for any sort of academic examinations. Their names were sent by local officials to the central government based on reputations and abilities, which were sometimes judged subjectively.
In 181 BC, after Prince Heng's brother, Prince Liu Hui of Zhao, committed suicide over his marital problems, Grand Empress Dowager Lü, who was then in effective control of the imperial government, offered the more prosperous Principality of Zhao to Prince Heng, but Prince Heng, judging correctly that she was intending on making her nephew Lü Lu prince, politely declined and indicated that he preferred remaining on the border. The grand empress dowager then created Lü Lu Prince of Zhao.
During these years, the Principality of Dai did in fact become a key position in the defense against Xiongnu, and Prince Heng became well-acquainted with Xiongnu customs and military strategies, although the extent of his own participation in military actions was unknown.
Examples of Emperor Wen's policies that showed kindness and concern for the people include:
In 179 BC, after some hesitation (during which he, apparently influenced by the theory of chanrang (禪讓), thought that maybe it would be more proper for him to find the wisest person in the empire and offer the throne to him, or that he should consider offering the throne to his uncle Liu Jiao (劉交), the Prince of Chu; his cousin Liu Pi (劉濞), the Prince of Wu; or his younger brother Liu Chang (劉長), the Prince of Huainan), he created his oldest son Liu Qi the Crown Prince and Prince Qi's mother, Consort Dou, Empress.
In addition to Empress Dou, Emperor Wen also favored Consort Shen (慎夫人). Despite her favored state, however, she only wore simple dresses rather than elaborate designs, as a means of savings.
Emperor Wen, during the early part of his reign, was often impressed with suggestions tendered by a young official, Jia Yi, but opposed by senior officials, he did not promote Jia to particularlly high positions; rather, Jia was put into a rotation as a teacher for various princes. Jia proposed dividing the larger principalities ruled by branch lines of the imperial family, a proposal that Emperor Wen agreed with but hesitated to actually carry out, and he did not actually implement Jia's proposal, which later might have prevented the Rebellion of the Seven States.
In 175 BC, over the objections of Jia Yi, Emperor Wen issued an edict permitting any person to mint money (then only in the form of coins) out of copper and tin. The main beneficiaries of this policy were those with access to copper, including the court official Deng Tong (鄧通) (see also below), to whom Emperor Wen had given a major copper mine in Yandao (嚴道, in modern Yaan, Sichuan), and Liu Pi, the Prince of Wu, whose principality had a major copper mine at Yuzhang (豫章, in modern Nanchang, Jiangxi).
In 174 BC, a major incident occurred involving Liu Chang, the Prince of Huainan, who was then Emperor Wen's only surviving brother. Emperor Wen had great affection for him and did not punish him for using styles and ceremonies that only emperors were supposed to use. Also, contrary to imperial laws, Prince Chang issued edicts within his own principality and also commissioned his own prime minister. He also carried out executions and created titles for people -- two powers that were also reserved to the emperor. Emperor Wen constantly excused him for his indiscretions -- which included assassinating Shen Yiji (審食其), the Marquess of Piyang -- but eventually became unhappy. He asked his uncle Bo Zhao (薄昭) to write a letter to Prince Chang to try to change his ways. Instead, Prince Chang was offended and planned a rebellion. When the conspiracy was discovered, Emperor Wen stripped Prince Chang of his title and exiled him to Yandao -- with the intent to teach him a lesson and then summoning him back. However, on the way, Prince Chang died -- probably by suicide. In 172 BC, Emperor Wen, missing Prince Chang dearly and still lamenting his death, created his sons Liu An, Liu Bo (劉勃), Liu Ci (劉賜), and Liu Liang (劉良) marquesses, again over Jia Yi's objection.
Also in 174 BC, when Xiongnu's new chanyu Laoshang came to power, Emperor Wen continued the heqin policy by giving him a prince's daughter in marriage.
In 170 BC, Emperor Wen's uncle Bo Zhao, who had been instrumental in his administration, killed an imperial messenger. Emperor Wen forced him to commit suicide. This incident drew criticism from later historians, who believed that he should have curbed Bo's powers in earlier and saved his life in that manner.
In 169 BC, Chao Cuo (晁錯), then a low level official, offered Emperor Wen a number of suggestions at dealing with Xiongnu. Emperor Wen was impressed, and made him a member of Crown Prince Qi's household. At Chao's suggestion, in 168 BC, Emperor Wen instituted the policy that if people contributed food for use by the northern defense force against Xiongnu, they could receive titles or have their crimes pardoned.
In 167 BC, Emperor Wen banned the corporal punishments of facial tattoo and cutting off the nose or a foot, and replaced them with whipping. These punishments would not be instituted against as a matter of formal legal sentencing for the rest of Chinese history. (However, as was later noted, this actually caused more deaths, and so the amount of whipping was further reduced in 156 BC by Emperor Jing.)
In 158 BC, when Xiongnu made a major incursion into the Commanderies of Shang (上, modern northern Shaanxi) and Yunzhong (雲中, modern western Inner Mongolia, centering Hohhot), Emperor Wen made a visit to the camps of armies preparing to defend the capital Chang'an against a potential Xiongnu attack. It was on this occasion when he became impressed with Zhou Bo's son Zhou Yafu as a military commander -- compared to the other generals, who, upon the emperor's arrival, dropped all things and did what they could to make the emperor feel welcome, Zhou remained on military alert and required the imperial guards to submit to proper military order before he would allow the imperial train to enter. Later, he would leave instructions for Crown Prince Qi that if military emergencies arose, he should make Zhou his commander of armed forces -- instructions that were heeded during the Rebellion of the Seven States.
Emperor Wen died in summer 157 BC. He was succeeded by Crown Prince Qi. Emperor Wen, in his will, reduced the usual mourning period to three days, contrary to the previous lengthy periods of mourning in which weddings, sacrifices, drinking, and the consumption of meat were disallowed, thus greatly reducing the burden on the people. He also ordered that his concubines be allowed to return home. (Before and after Emperor Wen, generally, imperial concubines without children were required to guard the emperor's tomb for the rest of their lives.)
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