生平

父親司馬覲於太熙元年（290年）去世後，司馬睿在翌年以十五歲之齡襲封琅邪王。襲爵後司馬睿卻遭遇到八王之亂開始，面對一段朝政混亂時期，司馬睿就表現得謙恭退讓，以圖逃避災禍，又因行事低調，當時也沒太多人注意到他。元康二年（292年）司馬睿拜員外散騎常侍。到了永安元年（304年）時，司馬睿已升為左將軍，並參與討伐成都王司馬穎的蕩陰之戰；但此戰由司馬穎獲得勝利，被帶著親征的晉惠帝被俘，戰前勸司馬穎投降的司馬睿叔父東安王司馬繇更被殺。司馬睿恐懼禍及自身，便逃返洛陽（今河南省洛陽市）接母親一同回到封國琅邪《晉書：元帝紀》：元康二年，拜員外散騎常侍。累遷左將軍，從討成都王穎。蕩陰之敗也，叔父東安王繇為穎所害。帝懼禍及，將出奔。其夜月正明，而禁衛嚴警，帝無由得去，甚窘迫。有頃，雲霧晦冥，雷雨暴至，徼者皆馳，因得潛出。穎先令諸關無得出貴人，帝旣至河陽，為津吏所止。從者宋典後來，以策鞭帝馬而笑曰：「舍長！官禁貴人，汝亦被拘邪！」吏乃聽過。至洛陽，迎太妃俱歸國。。

永興二年（305年），東海王司馬越起兵討伐在長安（今陝西西安）挾帝掌政的河間王司馬顒，就假司馬睿為輔國將軍；不久司馬越統兵西進，加司馬睿平東將軍、監徐州諸軍事，讓他留鎮下邳（今江蘇省邳州市）。在下邳期間，司馬睿就請了昔日在洛陽力勸自己返回封國的王導擔任自己的司馬，並讓他為自己出謀劃策。永嘉元年（307年），司馬睿聽從王導及東海王妃裴氏的建議《晉書·東海王越傳》：初，元帝鎮建鄴，裴妃之意也，帝深德之，數幸其第，以第三子沖奉越後。《晉書：元帝紀》：永嘉初，用王導計，始鎮建鄴，以顧榮為軍司馬，賀循為參佐，王敦、王導、周顗、刁協並為腹心股肱，賓禮名賢，存問風俗，江東歸心焉。，將駐地由下邳遷至東吳故都建鄴（今江蘇省南京市），並獲晉懷帝進為假節、安東將軍、都督揚州江南諸軍事。但司馬睿初到建鄴時未得江南士族禮敬，整整一個月都無人來訪，在王導及王敦的協助下終在江南士族中建立起聲望，司馬睿亦因而選任顧榮、賀循等江南士族領袖為僚佐，與王導、刁協等僑姓士族合作治理江東。司馬睿雖為皇族，然全因著王導、王敦而得江東人擁戴，遂為當時人稱「王與馬，共天下」《晉書·王敦傳》：帝初鎮江東，威名未著，敦與從弟導等同心翼戴，以隆中興，時人為之語曰：「王與馬，共天下。」〈司馬睿與王導。門閥政治格局的形成〉

永嘉四年（310年）十一月，鎮東將軍周馥以洛陽孤危，上書請晉懷帝遷都壽春（今安徽省壽縣），此舉因未有先詢問過主政的太傅司馬越而令對方大怒。周馥早前派了淮南太守裴碩領兵赴司馬越以應付對方對二人的徵召，此時裴碩就宣稱得到司馬越的密令，讓他討伐擅命的周馥，轉向進攻壽春。裴碩敗予周馥，被逼退守東城並向司馬睿求援，司馬睿遂派了揚威將軍甘卓及建威將軍郭逸領兵進攻壽春。永嘉五年正月，周馥守了十日而敗，出逃項縣為新蔡王司馬確所拘，不久則憂憤而亡。五月又進號鎮東大將軍、開府儀同三司。但六月就發生了永嘉之亂，洛陽失陷於漢趙且晉懷帝被俘，時司空荀藩逃到滎陽並移檄天下，推了司馬睿為盟主。司馬睿以盟主身分承制改易江州官員任命，但向來以洛陽懷帝政府尚在而拒絕接受司馬睿命令的江州刺史華軼再次不聽命，司馬睿便派王敦統領甘卓、周訪、宋典及趙誘等軍討伐華軼，華軼領兵積極抵抗，卻在衞展及周廣擔任內應之下遭到突襲，兵敗被殺《晉書·華軼傳》：軼自以受洛京所遣，而為壽春所督，時洛京尚存，不能祗承元帝教命，郡縣多諫之，軼不納，曰：「吾欲見詔書耳。」時帝遣揚烈將軍周訪率眾屯彭澤以備軼，訪過姑孰，著作郎幹寶見而問之，訪曰：「大府受分，令屯彭澤，彭澤，江州西門也。華彥夏有憂天下之誠，而不欲碌碌受人控禦，頃來紛紜，粗有嫌隙。今又無故以兵守其門，將成其釁。吾當屯尋陽故縣，既在江西，可以捍禦北方，又無嫌於相逼也。」尋洛都不守，司空荀籓移檄，而以帝為盟主。既而帝承制改易長吏，軼又不從命，於是遣左將軍王敦都督甘卓、周訪、宋典、趙誘等討之。軼遣別駕陳雄屯彭澤以距敦，自為舟軍以為外援。武昌太守馮逸次於湓口，訪擊逸，破之。前江州刺史衛展不為軼所禮，心常怏怏。至是，與豫章太守周廣為內應，潛軍襲軼，軼眾潰，奔於安城，追斬之，及其五子，傳首建鄴。。永嘉六年（312年），晉懷帝在漢趙都城平陽（今山西省臨汾市）被殺，消息在建興元年（313年）四月傳到長安後晉愍帝以皇太子即位為帝，並在五月壬辰日（6月27日）進侍中、左丞相、大都督陝東諸軍事，與大都督陝西諸軍事的右丞相南陽王司馬保分陝而治《晉書·愍帝紀》：（建興元年）五月壬辰，以鎮東大將軍、琅邪王睿為侍中、左丞相、大都督陝東諸軍事，大司馬、南陽王保為右丞相、大都督陝西諸軍事。。建興三年（315年）進位丞相，大都督中外諸軍事。

建武元年（317年），在上一年漢趙俘擄晉愍帝的消息隨平東將軍宋哲傳到建康後，宋哲宣稱有愍帝詔命以司馬睿總攝萬機，西陽王司馬羕為首的眾官員則請司馬睿登帝位，在司馬睿拒絕之下依魏晉兩朝先例改稱晉王，並於建康備百官，立社稷，並改元「建武」。同年晉愍帝被殺，消息在翌年（318年）傳到建康，百官勸進，司馬睿遂即帝位，改元「太興」。即位之時百官在旁，司馬睿特別請一手協助他移鎮江東並取得江南士族支持的王導和他一起同坐御座，惟王導推辭。

永昌元年（322年），大將軍、荊州牧王敦於武昌起兵，以誅劉隗為名進攻建康。司馬睿其實早就提防王敦，尤其前一年就派戴淵以征西將軍出鎮合肥（今安徽省合肥市）、劉隗以鎮北將軍鎮淮陰（今淮安市淮陰區）作外援，聞王敦起兵後便召他們入衞建康，並以王導為前鋒大都督，自己亦親身披甲在城郊檢閱六軍，積極抵抗。然而王敦兵臨建康時即攻石頭城，守城的周札開門迎敵，王敦遂控制石頭城。司馬睿隨後命令諸軍進攻石頭城，為王敦所敗。司馬睿無力抵禦王敦，只好妥協，王敦遂自授丞相主政。逼於王敦的司馬睿憂懼成疾，在同年閏十一月己丑日（323年1月3日）去世，時年四十七歲，葬建平陵，廟號中宗，諡元皇帝。

治理江東

南北形勢

司馬睿移鎮後南方時有的亂事：永嘉四年（310年）建威將軍錢璯作亂陽羨縣《晉書·周處傳》：初，呉興人錢璯亦起義兵討陳敏，越命為建武將軍，使率其屬會於京都。璯至廣陵，聞劉聰逼洛陽，畏懦不敢進。帝促以軍期，璯乃謀反。時王敦遷尚書，當應徵與璯俱西。璯陰欲殺敦，藉以舉事，敦聞之，奔告帝。璯遂殺度支校尉陳豐，焚燒邸閣，自號平西大將軍、八州都督，劫孫皓子充，立為呉王，既而殺之。來寇圮縣。帝遣將軍郭逸、郡尉宋典等討之，並以兵少未敢前。玘復率合鄉里義眾，與逸等俱進，討璯，斬之，傳首於建康。、建興元年（313年）在湘州起事，影響荊江湘三州的杜弢《晉書·杜弢傳》及在竟陵郡舉事作亂的杜曾。建興三年（315年）殺吳興太守袁琇的徐馥及在宣城郡舉事的吳末帝族人孫弼圖響應周勰的報復行動。《晉書·元帝紀》文末所載亦大致一樣，稱司馬睿是夏侯光姬與牛氏小吏私通所生《晉書·元帝紀》：初，《玄石圖》有「牛繼馬後」，故宣帝深忌牛氏，遂為二榼，共一口，以貯酒焉，帝先飲佳者，而以毒酒鴆其將牛金。而恭王妃夏侯氏竟通小吏牛氏而生元帝，亦有符雲。，魏收在修《魏書》更直接說司馬睿是牛金和夏侯光姬的私生子。

評價

• 唐代房玄齡於《晉書》的「史臣曰」評論說：「晉氏不虞，自中流外，五胡扛鼎，七廟隳尊，滔天方駕，則民懷其舊德者矣。昔光武以數郡加名，元皇（案：晉元帝）以一州臨極，豈武、宣餘化，猶暢於琅邪，文、景垂仁，傳芳於南頓？所謂後乎天時，先諸人事者也。馳章獻號，高蓋成陰，星斗呈祥，金陵表慶。陶士行擁三州之旅，郢外以安；王茂弘為分陝之計，江東可立。或高旌未拂，而遐心斯偃，回首朝陽，仰希乾棟，帝猶六讓不居，七辭而不免也。布帳綀帷，詳刑簡化，抑揚前軌，光啓中興。古首私家不蓄甲兵，大臣不為威福，王之常制，以訓股肱。中宗失馭強臣，自亡齊斧，兩京胡羯，風埃相望。雖復《六月》之駕無聞，而《鴻雁》之歌方遠，享國無幾，哀哉！」

• 唐代某貴族「公子」與虞世南的對話：「公子曰：『中宗值天下崩離，創立江左，俱為中興之主，比於前代，功德云何？』先生曰：『元帝自居藩邸，少有令聞，及建策南渡，興亡繼絕，委任宏茂，撫綏新舊，故能嗣晉配天，良有以也。然仁恕為懷，剛毅情少，是以王敦縱暴，幾危社稷，蹙國舒禍，其周平之匹乎？』」

家世

嗣父

• 晉武帝 司馬炎

妃嬪

• 虞孟母，追封元敬皇后

• 宮人荀氏，生司馬紹、司馬裒，335年卒

• 鄭夫人，生司馬煥、司馬昱、尋陽公主，326年卒，追封宣太后

• 石婕妤，生司馬衝

• 王才人，生司馬晞

子嗣

• 晉明帝 司馬紹（299年－325年）

• 琅邪孝王 司馬裒（300年－317年）

• 東海哀王 司馬沖（311年－341年）

• 武陵威王 司馬晞（316年－381年）

• 琅邪悼王 司馬煥（317年－319年）

• 晉簡文帝 司馬昱（320年－372年）

女兒

• 尋陽公主，嫁荀羨

注釋

Early career

Sima Rui was born in 276 in the then-Jin capital Luoyang, as the son of Sima Jin the Prince of Langya and his wife Princess Xiahou Guangji (夏侯光姬). (The Book of Wei claimed that he was not Prince Jin's biological son but the product of an affair that Princess Xiahou had with the general Niu Jin, but provided no real evidence, and the claim should be considered suspect.) His father died in 290, and he became the Prince of Langya. The Book of Jin referred to him as steady and dexterious, personality-wise.

In 304, in the midst of the War of the Eight Princes, Sima Rui participated in Sima Yue the Prince of Donghai's campaign against Sima Ying the Prince of Chengdu as a minor general. After Sima Ying defeated Sima Yue, Sima Yue executed Sima Rui's uncle Sima Yao the Prince of Dong'an, which caused Sima Rui much fear. He decided to flee back to his principality Langxie (roughly modern Weifang, Shandong), under counsel of Sima Yue's assistant Wang Dao, whom he befriended during the campaign. He first tried to head back to Luoyang, but when he was about to cross the Yellow River, he was stopped by guards instructed to stop any nobles or high level officials from crossing (as Sima Ying had ordered such, fearing that nobles would desert him or plot against him). His own guard Song Dian (宋典) then arrived and gave him a shove, pretending that they were just construction workers. The guards then allowed them to cross. After Sima Rui got to Luoyang, he took his mother Princess Dowager Xiahou and headed to Langxie, where they spent the next few years away from the War of the Eight Princes.

In 307, Sima Yue, who had emerged victorious in the aftermaths of the War of the Eight Princes as the regent for Emperor Huai, under the advice of his wife Princess Pei, commissioned Sima Rui as the military commander of parts of Yang Province (揚州, modern Zhejiang and southern Jiangsu and Anhui) south of the Yangtze River, with his post at Jianye. Wang Dao became his chief advisor. As Sima Rui lacked fame, after he arrived in Jianye, few of the powerful local gentlemen would come visit and support him. Under Wang Dao's counsel, Sima Rui personally visited He Xun (賀循) and Gu Rong (顧榮) and invited them to serve in his administration. He and Gu were well regarded by the local population, which eventually began to trust Sima Rui's leadership. Wang Dao and his cousin, the general Wang Dun, served in key roles, and it was said at the time that the domain was ruled equally by the Simas and the Wangs.《晉書·王敦傳》：帝初鎮江東，威名未著，敦與從弟導等同心翼戴，以隆中興，時人為之語曰：「王與馬，共天下。」〈司馬睿與王導。門閥政治格局的形成〉

After the fall of Luoyang

In 311, Luoyang fell to Han Zhao forces, and Emperor Huai was captured. A large number of refugees, fleeing Han Zhao forces, crossed the Yangtze River and arrived in Sima Rui's domain. Under Wang Dao's suggestion, Sima Rui sought out the talented men among them and added them to his administration. Meanwhile, he began to exercise more imperial power, and began to put all other provinces south of the Huai River under his own control—and, for the next few years, under the command of Wang Dun and other generals such as Tao Kan and Zhou Fang (周訪), the agrarian rebels resisting Jin rule in Jing (荊州, modern Hubei) and Xiang (湘州, modern Hunan) Provinces were gradually subjugated. However, he made no effort to try to send armies north against Han Zhao. Meanwhile, as his powerful assistants were largely refugees from the north, the native population began to be dissatisfied, and over the next few years there were constant frictions that decreased the effectiveness of Sima Rui's administration. In 315, members of the powerful Zhou clan intended to start an uprising against him, but the conspiracy was exposed by other members of the clan still loyal to Jin, and the conspiracy did not have a major impact. In 315, Wang Dun was finally able to suppress the remaining agrarian rebels in the west, and began to show ambitions and act independently of Sima Rui.

In 313, after Emperor Huai was executed by Han Zhao, Sima Ye, a nephew of Emperor Huai, was declared emperor (as Emperor Min) in Chang'an. Sima Rui was named the Left Prime Minister, a title that he accepted; however, he took no actual actions in aid of the emperor. (Meanwhile, as naming taboo for Emperor Min's name, Sima Rui's headquarters Jianye was renamed Jiankang, a name it would keep for several centuries.) When his general Zu Ti requested to lead an army north to, he gave Zu only supplies for one thousand men with no actual troops; Zu had to seek out his own soldiers, but was eventually able to recover a number of cities south of the Yellow River.

In 316, Chang'an fell to Han Zhao forces, and Emperor Min was captured. Sima Rui quickly declared that he was going to act against Han Zhao, but then quickly claimed a lack of supplies and cancelled the campaign. In spring 317, his officials requested that he take the throne, and after he declined initially, he took the title "King of Jin"—a title previously used by Sima Zhao while regent of Cao Wei—rather than emperor. He created his son Sima Shao crown prince.

Early reign and the loss of Northern China

In early 318, Han Zhao's emperor Liu Cong executed Emperor Min, and three months later, news arrived in Jiankang. Sima Rui then declared himself emperor (as Emperor Yuan). At this time, the areas directly under his control were roughly south of the Yellow River and east of the Three Gorges, although pockets of Jin territory in the north—chief among which was Youzhou (modern Beijing, Tianjin, and northern Hebei), controlled by the ethnic Xianbei governor Duan Pidi—largely also recognized him as emperor. However, while technically recognizing him as emperor, Zhang Shi the governor of Liang Province (modern central and western Gansu), chose not to use his era names and instead continued to use Emperor Min's era name of Jianxing—thus hinting non-recognition. (Also, he did not recognize and was non-committal to Sima Bao the Prince of Nanyang's claim for emperor despite his alliance with his father Zhang Gui and whose domain was closely related to the Zhangs, believing Emperor Yuan would be a more effective emperor but retaining Emperor Min's era name—thus showing another sign that the Zhangs sought independence from the Jin, though not immediately at the time.)

Late in 318, when the Han Zhao emperor Liu Can was overthrown by his official Jin Zhun, Jin Zhun initially indicated that he was submitting to Emperor Yuan's authority, and Emperor Yuan tried to take advantage by sending an army to assist Jin Zhun. However, long before the army could get there, Jin Zhun was defeated by the new Han Zhao emperor Liu Yao and the general Shi Le.

In 319, Duan Pidi's forces fell to Shi Le(who had by that point declared independence from Former Zhao as declared by Liu Yao, establishing Later Zhao in the same year) and Duan fled to another governor still loyal to Jin—Shao Xu the governor of Ji Province (冀州, modern central Hebei). In the next year, Shi Le sent his generals Shi Hu and Kong Chang to capture Shao. They captured him but Duan Pidi was able to take control of Shao's forces, thus once again leading the resistance in the north. While this is happening, remaining Jin resistance around west of Chang'an (or Northwest China, in this area Emperor Yuan has no control of these forces—instead this is where Zhang Shi (who technically recognized the emperor) has more control) began to falter as they entered internal conflict. When Sima Bao's domain (who had by then declared himself as Prince of Jin in previous year, ostensibly following the steps of Sima Zhao and did not recognize the emperor by this point) apparently suffering famine and faced Former Zhao invasion, Sima Bao tried to escape to Zhang Shi's domain but it is denied by the force Zhang Shi sent to 'protect' him but actually prevent Sima Bao from entering his domain. Failing to rescue himself, he presumably faced resistance by remaining generals under him (Yang Tao and Chen An (which had by this point defected to Han Zhao, but bearing some loyalty to him) soon apparently murdered by his generals Zhang Chun and Yang Ci, replacing him with his relative Sima Zhan (since Sima Bao had no sons). Soon after, Former Zhao forces led by Chen An attacked Sima Zhan's domain in revenge, killing him and in turn killing Zhang and capturing Yang, ending Jin resistance in the Qin Province. Later in the same year, Zhang Shi was assassinated by his guards Yan She (閻涉) and Zhao Ang, acting from the rumors spread by the magician Liu Hong. His brother and successor Zhang Mao (because Zhang Shi's son is still young at the time) executed Liu Hong and declared general pardon, effectively declaring his domain independent from the Jin, (because general pardon are the powers that was reserved for emperors, not the governor. Additionally, Zhang Mao began to use different era name Yongguang (永光) internally, while using Jianxing as an era name to communicate with other states, another definitive evidence that Zhang Mao's domain is effectively independent from the Jin) though he still continues to refer himself as Governor of the Liang Province. This action completely ended Jin rule in the Northwest China as his domain would continue evolving into vacillating state of Former Liang, especially by the time Zhang Jun ruled the state. By 321, Shao Xu's forces finally collapsed and Duan Pidi was captured by Shi Le (who had by that point declared independence from Former Zhao, establishing Later Zhao) in the same year), ending his resistance and all resemblance of Jin rule in China north of the Yellow River—although the Xianbei chief Murong Hui the Duke of Liaodong was still in control of modern Liaoning and still considered himself a Jin vassal.

Late reign and confrontation with Wang Dun

By 320, Emperor Yuan's relationship with Wang Dun was at a breaking point, as Wang Dun had grown more and more arrogant and controlling of the western provinces. Emperor Yuan feared him, and therefore began to group men around him who were against Wang Dun as well, such as Liu Huai and Diao Xie (刁協) -- men of mixed reputation who, in their efforts to suppress the Wangs' power offended many other people. In 321, Emperor Yuan commissioned Dai Yuan (戴淵) and Liu with substantial forces, claiming that they were to defend against Later Zhao attacks, but instead was intending to have them defend against a potential Wang Dun attack. (The general who had a charge of protecting Later Zhao attacks actually remain held by Zu Ti (by this time, he was a governor of Yu Province under Jin). Zu Ti is popular with the people he governed and was successful at holding his gains and attacks from Later Zhao (e.g. Shi Le sent Shi Hu against him in 317, but Zu was able to hold off. In another example next year, Chen Chuan defected and Zu was defeated but Shi was not able to advance further. In the end, this led into a stalemate, then informal detenté in which peace and trade relations are instituted with Yellow River as the border) When Zu Ti died, there is no one on the Jin checking the Later Zhao expansion against Jin. Because after Zu Ti died Chinese power left in the region often vacillated between Jin and Zhaos, these are Cao Ni (renegade general who ruled Qing Province) and Xu Kan (the only general who finally ended up surrendering to Jin). Both two often had a history of conflicts with the Jin, and both was defeated very quickly by Shi Hu, Later Zhao general. Because of these reasons, Jin was unable to do with these territories and gradually lost these territories between Yellow River and Huai River. By the time Cao Ni died, it is likely that Jin does not have any of these territories left thus losing it for decades until recovery by Huan Wen during Emperor Mu of Jin).

In spring 322, Wang Dun started his campaign against Emperor Yuan, claiming that Emperor Yuan was being deluded by Liu and Diao, and that his only intent was to clean up the government. He tried to persuade Gan Zhuo (甘卓), the governor of Liang Province (梁州, then consisting of modern northwestern Hubei and southeastern Shaanxi) and Sima Cheng the governor of Xiang Province to join him, and while both resisted, neither was effective in their campaigns against his rear guards. Wang quickly arrived in Jiankang, defeating Emperor Yuan's forces and entering and pillaging Jiankang easily. Liu fled to Later Zhao, while Diao, Dai, and Zhou Yi (周顗) were killed. Emperor Yuan was forced to submit and grant Wang Dun additional powers in the west. Wang Dun, satisfied, allowed Emperor Yuan to remain on the throne, and personally withdrew back to his home base of Wuchang (武昌, in modern Ezhou, Hubei). His forces then defeated and killed Sima Cheng, while a subordinate of Gan's, acting on Wang's orders, assassinated Gan.

After his defeat, Emperor Yuan grew despondent and ill. Around the new year of 323, he died. Crown Prince Shao succeeded to the throne as Emperor Ming.

Era names

• Jianwu (建武 jiàn wǔ) 317–318

• Taixing (太興 tài xīng) 318–322

• Yongchang (永昌 yǒng chāng) 322–323

Family

Consorts and Issue:

• Empress Yuanjing, of the Yu clan (元敬皇后 虞氏; 277–312), personal name Mengmu (孟母)

• Empress Dowager Jianwenxuan, of the Zheng clan of Xingyang (簡文宣皇太后 滎陽鄭氏; d. 326), personal name Achun (阿春)

　• Sima Huan, Prince Dao of Langxie (琅邪悼王 司馬煥; 317–318), fifth son

　• Sima Yu, Emperor Jianwen (簡文皇帝 司馬昱; 320–372), sixth son

　• Princess Xunyang (尋陽公主; b. 323)

　　• Married Xun Xian of Yingchuan (潁川 荀羨; 322–359) in 336

• Jieyu, of the Shi clan (婕妤 石氏)

　• Sima Chong, Prince Ai of Donghai (東海哀王 司馬衝; 311–341), third son

• Cairen, of the Wang clan (才人 王氏)

　• Sima Xi, Prince Wei of Wuling (武陵威王 司馬晞; 316–381), fourth son

• Lady, of the Xun clan (豫章君 荀氏; d. 335)

　• Sima Shao, Emperor Ming (明皇帝 司馬紹; 299–325), first son

　• Sima Pou, Prince Xiao of Langxie (琅邪孝王 司馬裒; 300–317), second son

Ancestry