|Reign||4 September 626 – 10 July 649|
Consort Xu Hui, concubine
Consort Yang, concubine
Consort Yin, concubine
Consort Wang, concubine
Consort Yan, concubine
Consort Wei, concubine
Consort Yang, concubine
Consort Yang , concubine
Consort Wu, concubine
|Li Chengqian, Crown Prince and Prince Min of Changshan
Li Ke, Prince of Wu
Li Tai, Prince Gong of Pu
Li Zhen, Prince of Yue
Li Zhi, Emperor Gaozong
Li Lize, the Princess Changle
Li Jing, the Princess Qinghe
Li Shu, the Princess Lanling
Li Mingda, the Princess Jinyang
|Li Shimin 李世民|
|Era name and dates|
|Zhenguan (貞觀): 4 September 626 – 10 July 649|
|Short: Wen Huangdi (文皇帝)
Full: Wen Wu Dasheng Daguang Xiao Huangdi
|House||House of Li|
|Father||Emperor Gaozu of Tang|
|Born||23 January 599
Qingshan Palace in Wugong, Sui China
|Died||10 July 649
Cuiwei Palace, Tang China
Emperor Taizong of Tang Dynasty (Chinese: 唐太宗; pinyin: Táng Tàizōng; Wade–Giles: T'ang T'ai-tsung) (23 January 599 – 10 July 649), personal name Li Shimin (Chinese: 李世民), was the second emperor of the Tang Dynasty of China, ruling from 626 to 649. As he encouraged his father, Li Yuan (later Emperor Gaozu) to rise against Sui Dynasty rule at Taiyuan in 617 and subsequently defeated several of his most important rivals, he was ceremonially regarded as a co-founder of the dynasty along with Emperor Gaozu.
He is typically considered as one of the(if not the) greatest emperors in Chinese history. Throughout the rest of Chinese history, Emperor Taizong's reign was regarded as the exemplary model against which all other emperors were measured, and his "Reign of Zhenguan" (simplified Chinese: 贞观之治; traditional Chinese: 貞觀之治; pinyin: Zhēnguān Zhī Zhì) was considered a golden age of Chinese history and required study for future crown princes. During his reign, Tang China flourished economically and militarily. For more than a century after his death, Tang China enjoyed peace and prosperity. During Taizong's reign, Tang was the largest and the strongest nation in the world. It covered most of the territory of present-day China, Vietnam, Mongolia and much of Central Asia as far as eastern Kazakhstan. It laid the foundation for Xuanzong's reign, which is considered Tang China's greatest era.
In 630, Emperor Taizong sent his general Li Jing against Eastern Tujue (proto Turks)-- to which Tang had once submitted—defeating and capturing its Jiali Khan Ashina Duobi and destroying Eastern Tujue power. This made Tang the dominant power in East and Central Asia, and Emperor Taizong subsequently took the title of Tian Kehan ("Heavenly Khan").
Unlike many of the nobility of the time, Emperor Taizong was a frank rationalist, openly scorning superstitions and claims of signs from the heavens. He also modified important rites in order to ease the burden of agricultural labour. The modern Chinese historian Bo Yang opined that Emperor Taizong achieved greatness by enduring criticism which others would find difficult to accept whilst trying hard not to abuse his absolute power (using Emperor Yang of Sui as a negative example), as well as through his employment of capable chancellors such as Fang Xuanling, Du Ruhui and Wei Zheng. Emperor Taizong's wife Empress Zhangsun also proved to be a capable assistant.
Lǐ Shìmín was born in 599 at Wugong (武功, in modern Xianyang, Shaanxi). His father Li Yuan the Duke of Tang was a general of the Sui Dynasty and a nephew, by marriage, to Sui's founding emperor Emperor Wen, as Li Shimin's grandmother Duchess Dugu was a sister of Empress Dugu Qieluo – both were daughters of Dugu Xin (獨孤信), a major general during Sui's predecessor dynasty Northern Zhou. Li Shimin's mother was Li Yuan's wife Duchess Dou, who was a daughter of Dou Yi (竇毅) the Duke of Shenwu and Dou Yi's wife, Northern Zhou's Princess Xiangyang. Duchess Dou bore Li Yuan four sons—an older brother to Li Shimin, Li Jiancheng, and two younger brothers, Li Xuanba (李玄霸, who would die in 614) and Li Yuanji – and at least one daughter (the later Princess Pingyang). Li Yuan named Li Shimin "Shimin" as a shortened form of the phrase "save the earth and pacify the people" (濟世安民, jishi anmin). Li Shimin apparently showed talent early in his life, and in 613, the official Gao Shilian, impressed with him, gave him a niece (the later Empress Zhangsun) in marriage as his wife; he was 14 and she was 12. In 615, when Emperor Wen's son and successor Emperor Yang was ambushed by Eastern Tujue forces at Yanmen (雁門, in modern Xinzhou, Shanxi), a general call was made for men to join the army to help rescue the emperor. Li Shimin answered that call and served under the general Yun Dingxing (雲定興), apparently doing so with distinction. In 616, when Li Yuan was put in charge of the important city of Taiyuan, Li Shimin followed his father to Taiyuan, while leaving at least three other sons—Li Jiancheng, Li Yuanji, and Li Zhiyun (李智雲, by Li Yuan's concubine Lady Wan) – at the ancestral home Hedong (河東, in modern Yuncheng, Shanxi).
Participation in the rebellion against Sui rule 
Emperor Yang was soon dissatisfied with Li Yuan and Wang Rengong (王仁恭), the governor of Mayi Commandery (馬邑, roughly modern Shuozhou, Shanxi), over their inability to stop Eastern Tujue incursions and the growing strengths of agrarian rebels, particularly the Eastern Tujue-support Liu Wuzhou the Dingyang Khan, who soon rose against Wang and killed him and soon captured Emperor Yang's secondary palace near Taiyuan. Li Yuan also became fearful that there had been prophecies throughout the empire that the next emperor would be named Li—and that Emperor Yang had killed another official, Li Hun (李渾) and Li Hun's clan over his fears that Li Hun's nephew, Li Min (李敏, the son-in-law of Emperor Yang's sister Yang Lihua, the Princess Leping), would seize the throne.
In fear, Li Yuan considered rebellion, and at that point, he did not know that Li Shimin had also been doing so—secretly discussing such plans with Li Yuan's associates Pei Ji and Liu Wenjing. Once Li Shimin's plans matured, he had Pei inform Li Yuan of them—and also had Pei warn Li Yuan that if it were revealed that Li Yuan had had sexual relations with some of Emperor Yang's ladies in waiting at the secondary Jinyang Palace (晉陽宮, which Pei was in charge with and had allowed Li Yuan to do so), all of them would be slaughtered. Li Yuan agreed to rebel, and after secretly summoning Li Jiancheng and Li Yuanji from Hedong and his son-in-law Chai Shao (柴紹) from the capital Chang'an, he declared a rebellion, claiming to want to support Emperor Yang's grandson Yang You the Prince of Dai, nominally in charge at Chang'an with Emperor Yang at Jiangdu (江都, in modern Yangzhou, Jiangsu), as emperor. He made both Li Jiancheng and Li Shimin major generals and advanced southwest, toward Chang'an. He created Li Shimin the Duke of Dunhuang. After defeating local Sui forces loyal to Yangdi, he defeated a Sui army of 30,000 men under the command of a veteran general of the wars in Korea outside of modern-day Beijing.
However, when Li Yuan arrived near Hedong, his army was bogged down by the weather. With food running out, there were rumors that Eastern Tujue and Liu Wuzhou would attack Taiyuan. Li Yuan initially ordered retreat, but at the earnest opposition by Li Jiancheng and Li Shimin, continued to advance. After defeating Sui forces at Huoyi (霍邑, also in modern Yuncheng), he decided to leave a small contingent to watch over Hedong while advancing across the Yellow River into Guanzhong (i.e., the Chang'an region). Once he did, he headed for Chang'an himself, while sending Li Jiancheng to capture the territory around the Tong Pass region to prevent Sui forces at Luoyang from reinforcing Chang'an and Li Shimin north of the Wei River to capture territory there. Meanwhile, Li Shimin's sister (Chai's wife) had also risen in rebellion in support of him, and she was able to gather a sizable army and capture some cities. She joined forces with Li Shimin and her husband Chai Shao. Soon, Li Yuan reconsolidated his forces and put Chang'an under siege. In winter 617, after defeating a large Sui army, he captured Chang'an from imperial forces and declared Yang You emperor (as Emperor Gong). He had himself made regent (with the title of grand chancellor) and created the Prince of Tang. (Meanwhile, most of the Sui territories and armies did not recognize Emperor Gong as emperor and continued to recognize Emperor Yang as emperor and not as retired emperor.) He created Li Shimin the Duke of Qin.
Li Yuan's control of the Chang'an region became almost immediately contested by the rebel ruler Xue Ju the Emperor of Qin, who sent his son Xue Rengao toward Chang'an. Li Yuan sent Li Shimin to resist Xue Rengao, and Li Shimin defeated Xue Rengao at Fufeng (扶風, in modern Baoji, Shaanxi), temporarily causing Xue Ju to toy with the idea of surrendering to Li Yuan, although Xue was subsequently dissuaded by his strategist Hao Yuan (郝瑗) from doing so.
In spring 618, with Sui's eastern capital Luoyang (where the officials in charge did not recognize Li Yuan's authorities) under attack by the rebel ruler Li Mi the Duke of Wei, Li Yuan sent Li Jiancheng and Li Shimin to Luoyang, ostensibly to aid the Sui forces at Luoyang but instead intending to test whether Luoyang might submit to him. The officials at Luoyang rebuffed his attempt at rapprochement, and Li Jiancheng and Li Shimin, not wanting to fight either them or Li Mi for control of Luoyang at this stage, withdrew. Li Yuan subsequently changed Li Shimin's title to Duke of Zhao.
In summer 618, when news arrived at Chang'an that Emperor Yang had been killed at Jiangdu in a coup led by the general Yuwen Huaji, Li Yuan had Emperor Gong yield the throne to him, establishing Tang Dynasty as its Emperor Gaozu. He created Li Jiancheng crown prince but created Li Shimin the Prince of Qin, also making him Shangshu Ling (尚書令), the head of the executive bureau of the government (尚書省, Shangshu Sheng) and a post considered one for a chancellor, while continuing to have Li Shimin serve as a major general as well.
During Emperor Gaozu's reign 
The campaign to reunify the empire 
The first thing that Li Shimin had to deal with was another incursion by Xue Ju, as Xue attacked Jing Prefecture (涇州, roughly modern Pingliang, Gansu) and Emperor Gaozu sent Li Shimin to resist Xue. Li Shimin established his defenses and refused to engage Xue to try to wear Xue Ju out, but at that time, he was afflicted with malaria, and he let his assistants Liu Wenjing and Yin Kaishan (殷開山) take command, ordering them not to engage Xue Ju. Liu and Yin, however, did not take Xue Ju seriously, and Xue Ju ambushed them at Qianshui Plain (淺水原, in modern Xianyang), crushing Tang forces and inflicting 50%–60% casualties. Li Shimin was forced to withdraw back to Chang'an, and Liu and Yin were removed from their posts. (This would be Li Shimin's only defeat recorded in historical records until the Goguryeo campaign of 645.) Xue Ju, in light of his victory, was ready to launch an assault on Chang'an itself, under Hao Yuan's advice, but suddenly died of an illness in fall 618 and was succeeded by Xue Rengao. Emperor Gaozu then sent Li Shimin against Xue Rengao. Three months after Xue Rengao took the throne, Li Shimin engaged him, and after a fierce battle between Li Shimin and Xue Rengao's major general Zong Luohou (宗羅睺), Li Shimin crushed Zong's forces, and then attacked Xue Rengao. Xue Rengao was forced to withdraw into the city of Gaozhi (高墌, in modern Xianyang as well), and once he did, his soldiers began surrendering to Li Shimin in mass. Xue Rengao was himself forced to surrender. Li Shimin had him delivered to Chang'an, where he was executed. Around new year 619, Emperor Gaozu made Li Shimin Taiwei (太尉, one of the Three Excellencies) and made him in charge of Tang operations east of the Tong Pass.
In spring 619, Liu Wuzhou launched a major offensive against Tang. He captured Taiyuan in summer 619, forcing Li Yuanji, who had been in charge there, to flee, and then continued his offensive south. Emperor Gaozu sent Pei Ji against him, but by winter 619, Liu had crushed Pei's forces and taken over nearly all of modern Shanxi. Emperor Gaozu, shocked at the development, considered abandoning the region altogether. Li Shimin opposed doing so and offered to lead the army against Liu. Emperor Gaozu agreed and commissioned him with an army. He crossed the Yellow River and approached Liu's major general Song Jingang (宋金剛) but did not engage him, choosing to try to wear Song out, only having his subordinates Yin Kaishan and Qin Shubao engage the other Dingyang generals Yuchi Jingde and Xun Xiang (尋相) in relatively low-level engagements. Eventually, in spring 620, when Liu and Song ran out of food supplies, they retreated, and Li Shimin gave chase, dealing Song a major defeat. Yuchi and Xun surrendered, and after Li Shimin chased further, both Liu and Song fled to Eastern Tujue. All of Dingyang territory fell into Tang hands.
In summer 620, Emperor Gaozu again commissioned Li Shimin against a major enemy—the former Sui general Wang Shichong, who had Sui's last emperor, Emperor Yang's grandson Yang Tong, yield the throne to him in 619, establishing a new state of Zheng as its emperor. When Li Shimin arrived at the Zheng capital Luoyang, Wang offered peace, but Li Shimin rebuffed him and put Luoyang under siege. Meanwhile, his subordinates took Zheng cities one by one. By winter 620, most of Zheng territory, other than Luoyang and Xiangyang, defended by Wang Shichong's nephew Wang Honglie (王弘烈), had submitted to Tang. Wang sought aid Dou Jiande the Prince of Xia, who controlled most of modern Hebei. Dou, reasoning that if Tang were able to destroy Zheng, his own Xia state would be next, agreed. He sent his official Li Dashi to try to persuade Li Shimin to withdraw, but Li Shimin detained Li Dashi and gave no response. Meanwhile, during the campaign, Li Shimin chose some 1,000 elite soldiers(玄甲軍), clad in black uniform and black armor, commanded by himself, to serve as advance troops, with Qin, Cheng Zhijie (程知節), Yuchi, and Zhai Zhangsun (翟長孫) as his assistants.
By spring 621, Luoyang was in desperate situation, and Xia forces had not yet arrived, but Tang troops had also suffered serious casualties, as Luoyang's defenses, aided by powerful bows and catapults, were holding. Emperor Gaozu, hearing that Dou had decided to come to Wang's aid, ordered Li Shimin to withdraw, but Li Shimin sent his secretary Feng Deyi to Chang'an to explain to Emperor Gaozu that if he did withdraw, Wang would recover and again be a major threat in the future. Emperor Gaozu agreed and allowed Li Shimin to continue to siege Luoyang. When Xia forward troops arrived first, Li Shimin surprised and defeated them, and then sent Dou a letter suggesting that he withdraw. Dou would not do so, and, against the advice of his wife Empress Cao and secretary general Ling Jing (凌敬) that he should instead attack Tang's prefectures in modern southern Shanxi, he marched toward Luoyang. Anticipating Dou's maneuver, Li Shimin left a small detachment, commanded by Li Yuanji, at Luoyang, while marching east himself, taking up position at the strategic Hulao Pass. When the armies engaged at Hulao, Li Shimin defeated Dou and captured him. He took Dou back to Luoyang and displayed him to Wang Shichong. Wang, in fear, considered abandoning Luoyang and fleeing south to Xiangyang, but as his generals pointed out that his only hope was Dou, he surrendered. Xia forces, after initially fleeing back to the Xia capital Ming Prefecture (洺州, in modern Handan, Hebei), also surrendered. Zheng and Xia territory were Tang's. Li Shimin returned to Chang'an in a grand victory procession, and, to reward Li Shimin, Emperor Gaozu awarded both him and Li Yuanji three mints so that they could mint money of their own. He also bestowed on Li Shimin the special title of "Grand General of Heavenly Strategies" (天策上將, Tiance Shangjiang). Meanwhile, Li Shimin's staff, already full of generals and strategists, were now being supplemented with a number of literary men.
The former Xia territory did not remain in Tang hands for long, as in winter 621, the Xia general Liu Heita rose against Tang rule, claiming to be avenging Dou, whom Emperor Gaozu had executed after Li Shimin took him back to Chang'an (against the latter's wishes). He was allied with Xu Yuanlang, a former agrarian rebel general who was nominally under Wang Shichong and who had submitted to Tang after Wang's defeat. Liu dealt successive defeats to Emperor Gaozu's cousin Li Shentong (李神通) the Prince of Huai'an, Li Xiaochang (李孝常) the Prince of Yi'an, and Li Shiji. Emperor Gaozu sent Li Shimin and Li Yuanji against Liu. In 622, after some indecisive battles with Liu, who had by that point taken over almost all of former Xia territory and claimed the title of Prince of Handong, Li Shimin defeated Liu by flooding his army with water from the Ming River (洺水, flowing near Ming Prefecture), and Liu fled to Eastern Tujue. Li Shimin then headed east and attacked Xu, defeating him. After leaving Li Shiji, Li Shentong, and Ren Gui (任瓌) to continue to attack Xu, Li Shimin returned to Chang'an.
The struggle against Li Jiancheng and Li Yuanji 
By this point, Li Shimin and his older brother Li Jiancheng, who was created crown prince in 618, reportedly after Emperor Gaozu first offered the position to Li Shimin due to his contributions, were locked in an intense rivalry, as Li Shimin's accomplishments caused people to speculate that he would displace Li Jiancheng as crown prince, and Li Jiancheng, while an accomplished general himself, was overshadowed by his younger brother. The court became divided into a faction favoring the Crown Prince and a faction favoring the Prince of Qin. The rivalry was particularly causing problems within capital, as the commands of the Crown Prince, the Prince of Qin, and the Prince of Qi (i.e., Li Yuanji) were said to have the same force as the emperor's edicts, and the officials had to carry conflicting orders out by acting on the ones that arrived first. Li Shimin's staff was full of talented men, but Li Jiancheng was supported by Li Yuanji, as well as Emperor Gaozu's concubines, who had better relationships with Li Jiancheng and Li Yuanji than they did with Li Shimin.
Late in 622, when Liu Heita returned to former Xia domain after receiving aid from Eastern Tujue, defeating and killing Li Shimin's cousin Li Daoxuan (李道玄) the Prince of Huaiyang, he again regained most of former Xia territory. Li Jiancheng's staff members Wang Gui and Wei Zheng suggested that Li Jiancheng needed to enhance his own reputation in battle, and so Li Jiancheng volunteered for the mission. Emperor Gaozu thus sent Li Jiancheng, assisted by Li Yuanji, to attack Liu. Li Jiancheng defeated Liu around the new year 623, and Liu was subsequently betrayed by his own official Zhuge Dewei (諸葛德威) and delivered to Li Jiancheng. Li Jiancheng killed Liu and returned to Chang'an in triumph. China was, by this point, roughly united under Tang rule.
For the next few years, the rivalry intensified, although during the meantime both Li Jiancheng and Li Shimin served as generals when Eastern Tujue made incursions. In 623, when the general Fu Gongshi rebelled at Danyang (丹楊, in modern Nanjing, Jiangsu), Emperor Gaozu briefly commissioned Li Shimin to attack Fu, but soon cancelled the order and sent Li Shimin's cousin Li Xiaogong the Prince of Zhao Commandery instead.
In 624, when Li Jiancheng was found to have, against regulations, tried to add soldiers to his guard corps, Emperor Gaozu was so angry that he put Li Jiancheng under arrest. In fear, Li Jiancheng's guard commander Yang Wen'gan (楊文幹) rebelled. Emperor Gaozu sent Li Shimin against Yang, offering to make him crown prince after he returned. After Li Shimin left, however, Feng Deyi (now a chancellor), Li Yuanji, and the concubines all spoke on Li Jiancheng's behalf, and after Li Shimin returned, Emperor Gaozu did not depose Li Jiancheng, but instead blamed the discord between him and Li Shimin on Li Jiancheng's staff members Wang Gui and Wei Ting (韋挺) and Li Shimin's staff member Du Yan, exiling them to Xi Prefecture (巂州, roughly modern Liangshan Yi Autonomous Prefecture, Sichuan).
Later that year, Emperor Gaozu, troubled by repeated Eastern Tujue incursions, seriously considered burning Chang'an to the ground and moving the capital to Fancheng, a suggestion that Li Jiancheng, Li Yuanji, and Pei Ji agreed with. Li Shimin opposed, however, and the plan was not carried out. Meanwhile, Li Shimin himself was sending his confidants to Luoyang to build up personal control of the army there. After an incident in which Li Shimin suffered a severe case of food poisoning after feasting at Li Jiancheng's palace—an event that both Emperor Gaozu and Li Shimin apparently interpreted as an assassination attempt—Emperor Gaozu considered sending Li Shimin to guard Luoyang to prevent further conflict, but Li Jiancheng and Li Yuanji, after consulting each other, believed that this would only give Li Shimin an opportunity to build up his personal power there, and therefore opposed it. Emperor Gaozu therefore did not carry out the plan. Meanwhile, the rivalry continued. Traditional historical accounts also indicated that at one point, when Li Shimin visited Li Yuanji's mansion, Li Yuanji wanted to assassinate Li Shimin, but Li Jiancheng, who could not resolve to kill a brother, stopped the plot. There was yet another incident in which Li Jiancheng, knowing that a horse threw its rider easily, had Li Shimin ride it, causing Li Shimin to fall off from it several times.
By 626, Li Shimin was fearful that he would be killed by Li Jiancheng, and his staff members Fang Xuanling, Du Ruhui, and Zhangsun Wuji were repeatedly encouraging Li Shimin to attack Li Jiancheng and Li Yuanji first—while Wei Zheng was encouraging Li Jiancheng to attack Li Shimin first. Li Jiancheng persuaded Emperor Gaozu to remove Fang and Du, as well as Li Shimin's trusted guard officers Yuchi Jingde and Cheng Zhijie, from Li Shimin's staff. Zhangsun, who remained on Li Shimin's staff, continued to try to persuade Li Shimin to attack first.
In summer 626, Eastern Tujue was making another attack, and under Li Jiancheng's suggestion, Emperor Gaozu, instead of sending Li Shimin to resist Eastern Tujue as he first was inclined, decided to send Li Yuanji instead. Li Yuanji was given command of much of the army previously under Li Shimin's control, further troubling Li Shimin, who believed that with the army in Li Yuanji's hands, he would be unable to resist an attack. Li Shimin had Yuchi summon Fang and Du back to his mansion secretly, and then on one night submitted an accusation to Emperor Gaozu that Li Jiancheng and Li Yuanji were committing adultery with Emperor Gaozu's concubines. Emperor Gaozu, in response, issued summonses to Li Jiancheng and Li Yuanji for the next morning, convening the senior officials Pei Ji, Xiao Yu, and Chen Shuda to examine Li Shimin's accusations. As Li Jiancheng and Li Yuanji approached the central gate leading to Emperor Gaozu's palace, Xuanwu Gate (玄武門), Li Shimin carried out the ambush he had set. He personally fired an arrow that killed Li Jiancheng. Subsequently, Yuchi killed Li Yuanji. Li Shimin's forces entered the palace and, under the intimidation of Li Shimin's forces, Emperor Gaozu agreed to create Li Shimin crown prince. Li Jiancheng's and Li Yuanji's sons were killed, and Li Shimin took Li Yuanji's wife Princess Yang as a concubine. Two months later, with Li Shimin firmly in control of power, Emperor Gaozu yielded the throne to him (as Emperor Taizong).