早年

李元吉为窦夫人所生，《新唐书》称其出生时，母亲窦夫人「恶其貌，不举，侍媪陈善意私乳之。」大业十二年（616年），李渊被任为太原留守，只将次子李世民带往太原，长子李建成、李元吉、五子李智云等都留在河东。次年，李世民说服李渊反隋，李渊派密使去河东召诸子，李建成和李元吉潜回太原，十四岁的李智云却被留下，后被隋朝杀害。

参与建唐

太原起兵时，李渊以李建成、李世民为大将，封李元吉为姑臧郡公。李渊出兵伐西时，让李元吉留守太原，后来封他为齐国公，管理十五郡的军事。李渊建唐后，封李元吉为镇北将军、太原道行军元帅，封齐王，为并州总管。武德二年，刘武周攻并州，于是高祖派右卫将军宇文歆助李元吉守之。李元吉凶猛好兵，在边地久了，愈发骄侈。乳母陈善意因劝阻他而死。李元吉好畋猎，称「我宁三日不食，不能一日不猎」，纵左右抢夺百姓。辅佐他的宇文歆劝谏无效便向皇帝李渊上表称李元吉游猎扰民，甚至当街射箭，以看人躲箭为乐，百姓怨恨。李元吉因而被免，又说服元老在宫门前请命，不久即复职。刘武周率五千骑至黄蛇岭，李元吉派车骑将军张达率五百步兵迎战，张达称军队少，李元吉坚持派他出战，全军覆没。张达怀恨，引刘武周攻陷榆次，进逼并州。李元吉起初击退刘武周进攻，但后来太常卿李仲文、尚书右仆射晋州道行军总管裴寂等援军都被刘武周所败后，晋州以北城镇都被刘武周所得，李元吉害怕，以率强兵出战为由骗司马刘德威率老弱守城，趁夜率妻妾弃军奔回京城，并州失陷。刘德威也弃太原，转移到马邑。李渊因李元吉年少没有苛责，不久加授侍中、襄州道行台尚书令、稷州刺史。武德三年，李世民收复并州。

武德四年，李世民征郑国王世充，夏王窦建德来救王世充，李世民进军虎牢关迎战之，留李元吉和屈突通围王世充于洛阳。王世充出兵，李元吉设伏击破之，斩首八百级，生擒其大将乐仁昉及甲士千馀人。李世民败俘窦建德，王世充害怕而投降，李世民和李元吉都因功受赏，李元吉加司空，加赐衮冕之服、前后部鼓吹乐二部、班剑二十人、黄金二千斤。唐高祖严格禁止铸钱，但允许李世民和李元吉各用三个炉子铸钱、裴寂用一个炉子铸钱。同年窦建德部将刘黑闼反唐并夺取窦建德故地，李世民和李元吉前去平定，李世民于次年春击败刘黑闼，迫使其逃往东突厥。兄弟俩又攻打叛首鲁王徐圆朗，李世民回长安，留李元吉对徐圆朗作战。但刘黑闼从突厥返回复夺窦建德故地，李元吉不能制止。

与尉迟融比武

李元吉善于使用马槊，听闻尉迟融擅长避槊，轻视之，想亲自试探尉迟融的本事，约定去掉槊刃，用竿互相刺。尉迟融却说即使有刃的槊也不能伤到自己，只去掉自己的槊刃，李元吉却始终不能用有刃的槊刺中尉迟融。李世民又命尉迟融夺取李元吉手中的槊，李元吉骑著马拿槊要刺尉迟融，但不一会儿就被尉迟融三次夺槊。李元吉素来骁勇，惊叹于尉迟融的本事，也引以为耻。

参与争储

太子李建成和李世民的矛盾激化，李元吉认为李建成必能为帝，支持他，李建成也许诺以后以他为皇太弟。李建成和李元吉与唐高祖的宠妃尹德妃、张婕妤交好，她们在高祖面前支持李建成，劝他不要改立李世民为太子。

武德五年（622年），李建成在王圭和魏徵建议下，请缨率军讨伐刘黑闼。高祖派他和李元吉前去。十一月，李元吉遣兵在魏州击破刘黑闼的弟弟刘十善。十二月，刘黑闼攻魏州受阻，李建成、李元吉率大军到昌乐，刘黑闼引兵拒战，但没有交战。李建成、李元吉领大军在馆陶击溃刘黑闼。刘黑闼北逃突厥，却被部将诸葛德威伏击擒获交给李建成，李建成杀刘黑闼。唐朝至此几乎一统中国。李元吉加授隰州总管。

李元吉与李建成各自招募壮士，多藏匿罪人，不但和妃嫔勾结，还厚赂中书令封德彝以为党助。唐高祖渐渐疏远李世民而爱李元吉。李世民曾随高祖幸齐王府，李元吉伏护军宇文宝于寝内，将刺杀李世民。李建成阻止李元吉，元吉怒道：「我是为兄长打算罢了，对我有何益处！」齐王典签裴宣俨免官，去秦王府做官，李元吉怀疑他泄密，鸩杀之。

武德七年，李世民让李建成因杨文干事件的谋反罪被唐高祖囚禁，高祖派李世民平定杨文干，许诺以李世民为太子，改封李建成为蜀王。但李世民出征后，高祖妃嫔、李元吉、宰相封德彝等都为李建成说话，高祖改变主意释放了李建成，仍以他为太子。同年，因突厥屡屡入侵，唐高祖想烧毁长安城，迁都樊城，李建成、李元吉、裴寂都同意，李世民却反对，迁都未能实行。

唐高祖在城南打猎，李建成、李世民、李元吉都相从，高祖命三子驰射角胜。李建成将肥壮却喜欢蹶倒的胡马给李世民，李世民乘之，马屡蹶倒，李世民却总能及时跳到数步外，便对宇文士及说：「他想这么杀我，但死生有命，怎么能伤到我？」有官员上疏夜观天象指李世民有天命为天下主。高祖大怒，先召李建成、李元吉，再召李世民指责，但正逢突厥入寇，高祖又改变态度与李世民商议对抗突厥，诏命李世民、李元吉率军出幽州御敌，并于兰池饯行。

八月，突厥可汗率万馀骑到豳州城西，列阵于五陇阪，唐军震恐。李世民对李元吉表示不能显示怯战，应该与之一战，并问李元吉是否愿意同行。李元吉畏敌不肯战，于是李世民让李元吉留下，顾自出阵，最终和平说退突厥。

后来李世民在李建成的太子东宫饮酒时，中毒吐血，世民和唐高祖都认为这是一起谋杀，高祖想派李世民去守卫洛阳，避免兄弟进一步冲突，但李建成和李元吉交换意见后认为这会使李世民在洛阳建立自己的势力，提出反对，高祖也就没有这么做。

九年（626年），转左卫大将军，不久进位司徒、兼侍中，并州大都督、隰州都督、稷州刺史等职如故。

身亡

护军薛宝曾上符籙谶字于元吉，「元吉合成唐字」，李元吉大喜，认为自己代表「唐朝」，只要除掉秦王李世民，取东宫易如反掌。

当年，高祖要去太和宫避暑，李世民、李元吉当相从，李元吉对李建成说：「等到了宫所，应当兴精兵袭取之，置于土窟中，只开一孔以通饮食。」正逢东突厥郁射设屯军河南，入围乌城，在李建成建议下，唐高祖打消了派李世民出征的念头，改派李元吉，要李世民部将秦琼、尉迟融、程知节、段志玄等都随征。原为李世民控制的军队大多被授权给李元吉统领。在魏徵鼓励下，李建成又说服高祖罢免李世民手下的房玄龄、杜如晦。高祖知其谋却不制止。李元吉又密请加害李世民，说：「秦王常违诏敕，平东都的时候就观望不急还京，分散钱帛以树私惠，违戾如此，岂非反逆？只需要速杀，何患无辞！」高祖不答，李元吉遂退。李建成对李元吉说：「如今已得秦王精兵，统数万之众，我与秦王至昆明池，宴别的时候令壮士拉之于幕下，说是暴卒，主上不会不信。我当使人进言让我执掌国务。正位以后，以你为太弟。敬德（尉迟融）等已入你手，一时坑之，谁敢不服？」率更丞王晊闻其谋，密告李世民。李世民召府僚以告，府僚都说：「大王若不正断，社稷非唐所有。若使建成、元吉肆其毒心，群小得志，元吉狼戾，终亦不事其兄。」李世民因而派尉迟融密召房玄龄、杜如晦回府，一夜，向唐高祖弹劾李建成、李元吉与庶母尹德妃、张婕妤通奸偷情，淫乱后宫。高祖下令次早召见李建成、李元吉，计划召集宰相裴寂、萧瑀、陈叔达来核实李世民弹劾的内容。次早，李世民在长安城宫城玄武门发动玄武门之变，李元吉与李建成途径临湖殿时，发现异常，急忙调头回走，此时伏兵杀出。李元吉三次对李世民射箭，都未能拉满弓，李世民却一箭射杀李建成。尉迟融率七十骑赶到，李世民左右将李元吉射落马下。这时李世民马受惊，驰入林中，李世民坠马不起，李元吉赶到，夺其弓，欲用弓弦勒杀之，尉迟融骑马赶到呵斥他，李元吉丢下李世民，欲逃到武德殿中寻求父皇庇护，却被尉迟融追上射死。李世民军入宫，迫使李渊以李世民主军国事。李建成、李元吉的手下闻讯攻打玄武门，李世民手下将二人首级割下示众，其众便溃散。事后，李元吉的五个儿子都被处死，父子皆从宗室中除名。李元吉遗孀王妃杨氏还为李世民生下一子李明，后来封为曹王。

身后

李世民后被李渊立为皇太子，即位后，追封元吉为海陵郡王，谥「剌」，以礼改葬。贞观十六年（642年），又追封巢王。唐高宗时，以曹王李明嗣其后。

家庭

妻妾

• 王妃杨氏（？－647年），元吉死后受唐太宗宠爱，其后生子李明

• 某姬，生归仁县主，墓志提及归仁县主在贞观二十一年（647年）「丁某忧」，可能是指生母逝世

子女

• 长子 李承业（梁郡王）

• 次子 李承鸾（渔阳王）

• 三子 李承奖（普安王）

• 四子 李承裕（江夏王）

• 五子 李承度（义阳王）

• 某女 和静县主 嫁薛元超

• 某女 寿春县主 嫁杨师道子杨豫之

• 某女 文安县主（623年－648年） 嫁段俨

• 六女 新野县主李令，字淑绚，武德七年（624年）生，637年受封，次年嫁裴重晖，662年卒

• 某女 归仁县主（625年－668年9月17日），644年嫁天水姜氏长道县公姜謩第二子

注释

Background

Li Yuanji was born in 603, during the reign of Emperor Wen of Sui. He was the fourth and final son of Li Yuan the Duke of Tang, a hereditary noble, and Li Yuan's wife Duchess Dou, who was herself the daughter of Dou Yi (窦毅) the Duke of Shenwu and Northern Zhou's Princess Xiangyang. He had three older brothers by Duchess Dou -- Li Jiancheng, Li Shimin, and Li Xuanba (李玄霸, who died in 614). She also gave birth to an older sister of Li Yuanji's, the eventual Princess Pingyang.

In 616, with agrarian rebellions beginning to engulf northern China and frequent Eastern Tujue incursions across the border, Emperor Yang of Sui commissioned Li Yuan to be the commander of the forces at Taiyuan, guarding it against both agrarian rebels and Eastern Tujue. At that time, Li Yuan took Li Shimin with him to Taiyuan, but left Li Jiancheng, Li Yuanji, another son Li Zhiyun (李智云), and the rest of his household at Hedong (河东, in modern Yuncheng, Shanxi). In 617, Li Yuan, fearful that Emperor Yang might punish him for his inability to suppress the rebels led by Liu Wuzhou the Dingyang Khan, was persuaded by Li Shimin to rebel against Sui rule. He then sent secret messengers to Hedong to summon his sons and to the capital Chang'an to summon his daughter and son-in-law Chai Shao (柴绍). Li Jiancheng and Li Yuanji secretly travelled to Taiyuan, but left the 13-year-old Li Zhiyun at Hedong.

Participation in Tangs founding

Even before Li Jiancheng, Li Yuanji, and Chai Shao (who, at the urging of Li Yuan's daughter, left Chang'an on his own while she went into hiding) arrived at Taiyuan, Li Yuan rebelled, declaring that he wanted to support Emperor Yang's grandson Yang You the Prince of Dai, then nominally in charge at Chang'an, as emperor, while honoring Emperor Yang as Taishang Huang (retired emperor). In response, Sui officials arrested Li Zhiyun, took him to Chang'an, and executed him.

Li Yuan made Li Jiancheng and Li Shimin both key generals, but the younger Li Yuanji was not, initially, although Li Yuan created him the Duke of Guzang. When Li Yuan subsequently began his campaign toward Chang'an, he left Li Yuanji in charge at Taiyuan. Later that year, after he captured Chang'an and declared Yang You emperor (as Emperor Gong) but kept power for himself as regent, he created Li Yuanji the Duke of Qi and put him in charge of the 15 commanderies around Taiyuan.

In spring 618, Emperor Yang, then at Jiangdu (江都, in modern Yangzhou, Jiangsu), was killed in a coup led by the general Yuwen Huaji. When the news arrived at Chang'an, Li Yuan had Yang You yield the throne to him, establishing the Tang dynasty as its Emperor Gaozu. He created Li Yuanji the Prince of Qi.

It was said that, while he was at Taiyuan, Li Yuanji was arrogant and wasteful, and he often held military exercises with his concubines and servants, involving use of actual armor and arms, and they suffered many casualties in these exercises, including injuries to Li Yuanji himself. His wet nurse Chen Shanyi (陈善意) tried to get him to change his ways, but he had his guards batter her to death. In spring 619, when his assistant Yuwen Xin (宇文歆) reported this to Emperor Gaozu, Emperor Gaozu temporarily removed him from his post. Less than a month later, however, with the people of Taiyuan petitioning to have Li Yuanji kept in charge, Emperor Gaozu restored him. (The traditional historians allege that Li Yuanji pressured the people into petitioning Emperor Gaozu.)

In summer 619, Liu Wuzhou launched an attack on the Taiyuan region, and Li Yuanji sent the general Zhang Da (张达) to resist Liu, despite Zhang's protestations that the army given him was too small to resist Liu. When Zhang was in fact defeated, he surrendered to Liu and served as Liu's guide in subsequent attacks. Liu soon put Taiyuan under siege, and while Li Yuanji initially repelled him, Liu was soon back and again had Taiyuan under siege. In fall 619, Li Yuanji fled with his wife and concubines back to Chang'an, and Liu captured Taiyuan, moving his capital from Mayi (马邑, in modern Shuozhou, Shanxi) there. (In 620, Li Shimin defeated Liu and recaptured the region.)

In 621, with Li Shimin leading the army in besieging Luoyang, the capital of Wang Shichong's rival Zheng state, Li Yuanji served as Li Shimin's assistant. When subsequently another rival ruler, Dou Jiande the Prince of Xia, came to Wang's aid, Li Shimin left Li Yuanji at Luoyang to continue the siege and to watch Wang, while he himself advanced to Hulao Pass to engage Dou. Li Shimin defeated and captured Dou at the Battle of Hulao, and Wang, in fear, surrendered. Li Shimin received the most honors stemming from the victory, but Li Yuanji also received promotions and honors. Subsequently, when Emperor Gaozu had the government mint new coins, there were strict prohibitions against minting by any other persons, except that Li Shimin and Li Yuanji were each granted the right to have three mints and Pei Ji was granted the right to have one mint. Later that year, when Dou's general Liu Heita rose in resistance to Tang rule and took over all of Dou's former territory, Li Shimin and Li Yuanji were sent against him. Li Shimin defeated Liu in spring 622, forcing Liu to flee to Eastern Tujue. Subsequently, they attacked another rebel leader, Xu Yuanlang the Prince of Lu, when Li Shimin returned to Chang'an and left Li Yuanji in charge of the operations against Xu. Meanwhile, however, Liu returned from Eastern Tujue and again occupied Dou's old territory, and Li Yuanji was not able to stop him.

Role in the rivalry between Li Jiancheng and Li Shimin

Meanwhile, an intense rivalry had developed between Li Jiancheng, who as the oldest son was Emperor Gaozu's crown prince, and Li Shimin, as Li Jiancheng, while a capable general himself, was overshadowed by Li Shimin, who had done much to solidify Tang rule by destroying Liu Wuzhou, Wang Shichong, Dou Jiande, and Xue Rengao. Li Yuanji supported Li Jiancheng in this rivalry, as he believed that if Li Jiancheng became emperor, Li Jiancheng would create him crown prince. Since their mother Duchess Dou had died in 614, the fact that Li Jiancheng and Li Yuanji had better relations with Emperor Gaozu's favored young concubines than Li Shimin did take a notable importance, since those concubines helped rehabilitate Li Jiancheng's standing before Emperor Gaozu, causing him to no longer consider making Li Shimin crown prince instead, as he considered at one point.

After Liu Heita returned from Eastern Tujue and reoccupied old Xia territory, Li Jiancheng, at the suggestion of his staff members Wang Gui and Wei Zheng, volunteered to lead the army against Liu. Emperor Gaozu thus sent Li Jiancheng, assisted by Li Yuanji, against Liu. Around the new year 623, with Liu's forced bogged down while attacking Tang's Wei Prefecture (魏州, in modern Handan, Hebei), Li Jiancheng and Li Yuanji engaged him at Guantao (馆陶, in modern Handan as well), crushing him. Liu fled north toward Eastern Tujue, but was ambushed and captured by his own official Zhuge Dewei (诸葛德威), who delivered him to Li Jiancheng. Li Jiancheng executed Liu. China was by this point almost completely unified by Tang. At one point, Li Yuanji tried to persuade Li Jiancheng to have Li Shimin assassinated when Li Shimin was visiting Li Yuanji's mansion, but Li Jiancheng, not having the heart to kill a brother, stopped Li Yuanji from doing so.

In 624, Li Jiancheng requisitioned a number of soldiers from the general Li Yi the Prince of Yan, to supplement his guard corps, against Emperor Gaozu's regulations. When this was revealed to Emperor Gaozu, Emperor Gaozu rebuked Li Jiancheng and exiled his guard commander Keda Zhi (可达志). When, subsequently, Li Jiancheng nevertheless requested the commandant at Qing Prefecture (庆州, in modern Qingyang, Gansu), Yang Wen'gan (杨文干), to conscript troops, presumably to guard against Li Shimin, the officers Erzhu Huan (尔朱焕) and Qiao Gongshan (桥公山) informed Emperor Gaozu that Li Jiancheng was encouraging Yang to start a rebellion so that they could seize power together. Emperor Gaozu, then at Renzhi Palace (仁智宫, in modern Tongchuan, Shaanxi), was incensed, and summoned Li Jiancheng, then at Chang'an, to Renzhi Palace. Li Jiancheng briefly flirted the idea of occupying Chang'an and not accepting the order, but eventually reported to Renzhi Palace to request forgiveness. Emperor Gaozu put him under arrest. When Yang heard this, Yang rebelled, and Emperor Gaozu, after promising Li Shimin that he would be made crown prince, sent Li Shimin to attack Yang. (Under Emperor Gaozu's promise, Li Jiancheng would be removed as crown prince and created the Prince of Shu instead. He would then send Li Jiancheng to the modern Sichuan region.) Once Li Shimin left, however, Li Yuanji, Emperor Gaozu's concubines, and the chancellor Feng Deyi, all spoke on Li Jiancheng's behalf, and Emperor Gaozu changed his mind, released Li Jiancheng, and allowed him to return to Chang'an and remain as crown prince. Instead, Emperor Gaozu only blamed the discord between his sons on Li Jiancheng's staff members Wang Gui and Wei Ting (韦挺), and Li Shimin's staff member Du Yan, exiling them. Yang was subsequently assassinated by his own subordinates.

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 (樊城, in modern Xiangfan, Hubei), a suggestion that Li Jiancheng, Li Yuanji, and the chancellor 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.

Death

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 Gong and Cheng Zhijie (程知节), 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 (玄武门), Li Shimin carried out the ambush he had set. He personally fired an arrow that killed Li Jiancheng. Subsequently, Li Yuanji tried to kill Li Shimin, but Yuchi killed Li Yuanji instead during the struggle. 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, and two months later passed the throne to him (as Emperor Taizong). Li Yuanji's five sons were all executed as well. Emperor Taizong also took Li Yuanji's wife Princess Yang as a concubine.

Li Yuanji was initially posthumously reduced to commoner rank. After Emperor Taizong took the throne, he posthumously created Li Yuanji the Prince of Hailing, with the unflattering posthumous name of La (meaning "ungrateful"). In 642, Emperor Taizong changed Li Yuanji's posthumous title to the greater title of Prince of Chao, and adopted his own son, by Consort Yang (Li Yuanji's widow), Li Ming (李明) the Prince of Cao (note difference in title) into Li Yuanji's line, as Li Yuanji's heir.

Family

Consort and their respective issue(s):

• Princess Consort of Chao, of the Yang clan of Hongnong (巢王妃 弘农杨氏), niece of Yang Gongren

　• Princess of Xinye (新野县主, 624-662), personal name Ling (令), 6th daughter

　　• Married Pei Chonghun of Hedong, Duke Chongling (万年县令 裴重晖) in 638 and had issue (two daughters)

• Concubine, of a certain clan (某姬)

　• Princess Guiren (归仁县主, 625- 17 September 668), 2nd daughter

　　• Married the 2nd son of Jiang Yu of Tianshui (天水)

• Unknwon

　• Chengye, Prince of Liang (李承业梁郡王), 1st son

　• Li Chengluan, Prince of Yuyang (李承鸾 渔阳王), 2nd son

　• Li Chengjiang, Prince of Pu'an (李承奖 普安王), 3rd son

　• Li Chengyu, Prince of Jiangxia (李承裕 江夏王, 4th son

　• Li Chengdu, Prince of Yiyang (李承度 义阳王), 5th son

　• Princess of Wen'an (文安县主, b. 623), 1st daughter

　　• Married Suan Yan (段俨)

　• Princess Hejing (和静县主), 3rd daughter

　　• Married Xue Yuanchao, Baron of Fenyin (汾阴男薛元超) and had issue (three sons)

　• Princess Shouchun (寿春县主), 4th daughter

　　• Married Yang Yuzhi (杨豫之)

　• Fifth Daughter