| 网笔号： | 文武大圣大广孝皇帝 | |||||||||||||
| 庙号： | 太宗 | |||||||||||||
| 陵墓： | 昭陵 | |||||||||||||
阅读李世民 Li Shimin在百家争鸣的作品!!! 阅读李世民 Li Shimin在诗海的作品!!! | ||||||||||||||
生卒时间：隋文帝开皇十八年十二月二十二日（公元599年）——唐太宗贞观二十三年（649年）五月二十六日（50岁）
庙号:太宗
谥号：文皇帝（唐高宗加谥文武圣皇帝；唐玄宗加谥文武大圣皇帝、文武大圣大广孝皇帝）
历史地位：民族英雄、天可汗、千古一帝
【唐太宗早年】
唐太宗于隋开皇十八年十二月二十二日（公元599年）出生于武功别馆，是唐高祖李渊与窦皇后的次子。公元614年娶妻长孙氏，武德九年八月二十一日立为皇后，即长孙皇后。
隋大业十一年（615年），隋炀帝被突厥十万骑围困于雁门（今山西代县），李世民应募从屯卫将军云定兴前往救援，提出虚张军容，昼引旌旗数十里，夜以钲鼓相应的疑兵计。时值东都及诸郡援兵亦至忻口（今忻县北），迫使突厥始毕可汗解围而去。十三年六月，与其兄李建成率兵攻西河（今汾阳），首战获胜，促使李渊决意西向关中。任右领军大都督，统右三军，封敦煌郡公。七月随李渊自太原（今太原西南）南下。途中李渊一度动摇，欲还师更图后举。世民坚决主张继续进军，提出先入咸阳，号令天下的方略。八月，进攻霍邑（今霍州），先率轻骑至城下，诱隋守将宋老生出战，继而率骑猛冲其侧背，配合李渊、建成正面攻击，斩宋老生，克其城。九月，军至河东（今永济西南），力主急速进军长安（今西安），遂奉命率前军西渡黄河，顺利占领渭河以北地区，各大族豪强纷至军门投效，数支农民起义军亦来归附，兵力迅速发展至13万人。十一月，会诸军攻克长安。李渊立代王杨侑为帝，即隋恭帝，改大业十三年为义宁元年。以光禄大夫、大将军、太尉唐公为假黄钺、使持节、大都督内外诸军事、尚书令、大丞相，进封唐王，李世民为京兆尹，改封秦公，义宁二年三月，为右元帅，徙封赵国公。
同年（618年）五月，隋恭帝禅位于唐，唐王即皇帝位，国号大唐，改元武德。武德元年，以赵公世民为尚书令、右翊卫大将军，进封秦王。
唐朝建立以后，为统一全国，先后进行了六次大的战役。这六个战役李世民就指挥了四个，全部取得了胜利，为唐王朝立下了赫赫战功。
第一次是对陇右薛举父子集团的战役，唐武德元年，薛举率军进攻关中，双方在现陕西长武县发生激战，在这里，李世民打了他一生中唯一的一次大败仗，退回长安。但不久，他便在浅水原之战彻底打败薛军，消灭了陇东集团。
第二次，刘武周依附突厥，南下进攻唐朝，攻占了晋阳，李世民不畏艰险，终于击溃了敌人主力，并乘胜追击，两天不吃饭，三天不解甲，彻底消灭了敌军，收复了丢失的土地。
第三次是对王世充和窦建德的战役。这次战役规模为唐统一战争中最大的。在这次战役中，李世民先将王世充击败，围困在洛阳，令其无粮草供应，待其自毙。就在洛阳将下未下之时，河北的窦建德军十余万众号称三十万为救援王世充，突然出现在唐军背后，李世民力排众议，在虎牢之战中大败窦建德军，生擒窦建德。洛阳的王世充也只得投降，这次李世民一举两克，取得了决定性的胜利。
第四次是平定刘黑闼的战役，刘黑闼是窦建德的部下，他打着为窦建德复仇的旗号，在河北起兵反唐。李世民指挥了平定其第一次起兵的战役，仅仅两个月就取得了胜利。（其他两个战役是由李孝恭指挥的平定杜伏威的江淮军和平定以江陵为根据地的萧铣的梁政权）。
李世民自此威望日隆，尤其是在虎牢之战后进入长安时，受到部分军民以皇帝的礼仪招待。武德四年冬十月，封为天策上将、领司徒、陜东道大行台尚书令，食邑增至二万户。高祖又下诏特许天策府自置官属，俨然形成一个小政府机构。
李世民在战斗中注重战前侦察，虽屡次遇险，但每次战斗都能作到知己知彼，善于制造战机，当敌强我弱时，他经常用“坚壁挫锐”的战法拖垮敌人，战斗中身先士卒，亲自率领骑兵突击敌阵，胜利后勇追穷寇，不给敌人喘息之机，因此获得了每次战役的胜利。在统一边疆的战争中，他运筹帷幄，决胜千里，明于知将，选拔良才，取得了战争的胜利。李世民用他卓越的军事才能，为大唐帝国的建立和发展做出了巨大的贡献，他不愧为我国历史上杰出的军事家，他的赫赫武功也永垂青史！
【玄武门之变】
玄武门之变发生于唐高祖武德九年（626年）。617年，李渊在李世民支持下在太原起兵反隋并很快占领长安。618年，隋炀帝被宇文化及缢杀之后，李渊建立唐朝，并立世子李建成为太子。据说太原起兵是李世民的谋略，李渊曾答应他事成之后立他为太子。但天下平定后，李世民功名日盛，李渊却犹豫不决。李建成随即联合四弟齐王李元吉，排挤李世民。李渊的优柔寡断，也使朝中政令相互冲突，加速了诸子的兵戎相见。是年，李建成向李渊建议由李元吉做统帅出征突厥，借此要把握住秦王的兵马，以防止李世民篡夺皇太子之位。李世民在危急时刻决定背水一战，先发制人。抢先一步杀死大哥李建成和四弟李元吉，这就是历史上有名的玄武门之变。玄武门事变之后仅仅三天李世民便被立为皇太子，从他父亲手里接过政府的实际控制权。八月初九，唐高祖被逼退位，李世民便做了唐王朝的第二位皇帝。
【史学评价】
《新唐书》：
甚矣，至治之君不世出也！禹有天下，传十有六王，而少康有中兴之业。汤有天下，传二十八王，而其甚盛者，号称三宗。武王有天下，传三十六王，而成、康之治与宣之功，其余无所称焉。虽《诗》《书》所载，时有阙略，然三代千有七百余年，传七十余君，其卓然著见于后世者，此六七君而已。呜呼，可谓难得也！
《旧唐书》评价：
史臣曰：臣观文皇帝发迹多奇，聪明神武。拔人物则不私于党，负志业则咸尽其才。所以屈突、尉迟，由仇敌而愿倾心膂；马周、刘洎，自疏远而卒委钧衡。终平泰阶，谅由斯道。尝试论之：础润云兴，虫鸣螽跃。虽尧、舜之圣，不能用檮杌、穷奇而治平；伊、吕之贤，不能为夏桀、殷辛而昌盛。君臣之际，遭遇斯难，以至抉目剖心，虫流筋擢，良由遭值之异也。以房、魏之智，不逾于丘、轲，遂能尊主庇民者，遭时也。况周发、周成之世袭，我有遗妍；较汉文、汉武之恢弘，彼多惭德。迹其听断不惑，从善如流，千载可称，一人而已！
吴兢在《贞观政要·序》中说：“太宗时政化，良足可观，振古而来，未之有也。”
《贞观政要》集论的撰者元朝的戈直说：“夫太宗之於正心修身之道，齐家明伦之方，诚有愧於二帝三王之事矣。然其屈己而纳谏，任贤而使能，恭俭而节用，宽厚而爱民，亦三代而下，绝无而仅有者也。后之人君，择其善者而从之，其不善者而改之，岂不交有所益乎！”这里所说，太宗在正心修身，齐家明伦方面，有愧於二帝三王之事，主要是指太宗与其兄李建成的皇位之争。
明宪宗在命儒臣订正重刊《贞观政要》时写道：“太宗在唐为一代英明之君，其济世康民，伟有成烈，卓乎不可及已。所可惜者，正心修身，有愧於二帝三王之道，而治未纯也。”
【丰功伟绩】
1. 他不拘一格的用人，对人材的使用及领导达到了极高的境遇；
2 .他独具慧眼，看到了个人力量的不足，充分认识到君王如石、良臣如匠，方有美玉问世，对大臣的各项进步之言豁达地予以采纳；
3 .不独断专行、初步确立了三权分立、互相监督的政治管理制度，规定法令甚至包括自己（影响国家政策的那一部分）旨意需门下省审查副署后方可生效发布，保证了政策的可行性、及时发现并纠正。杜绝了不良政策对国家及人民的违害与影响；
4 .认识到人命至重、不可妄杀的法政政策，规定死刑需三复奏（外地五复奏）复审批准后方可行刑，这就不难认人们想起贞观四年（630年）全国判死刑才29人、贞观六年（632年）全国死刑犯390人，太宗审查时令全部390人回家团年、待来年秋收后回来复刑，结果390人均准时到来、无一人逃亡。
5 .太宗朝武功之盛，除对高句丽战争上没有取得战略胜利外都取得了辉煌的胜利（东突厥、吐谷浑、高昌、安西四镇、漠北薛延陀等），这与当时的国力、军队战斗力、整体战略、用人选将与配合默契、过程协调一致等重要因素是分不开的，因此在中华历史上的名将名相中，贞观朝占有相当的比例，在中华军事史上，贞观朝的战例也多被引用；
6 . 气吞天下的“天可汗”气质，李世民多次以少吓多，经典之役就是在渭水单骑吓退突厥10万精骑，就对比宋真宗在寇准一再坚持和请求下才勉强在大军护卫下到达澶州南城，而又要战战兢兢的马上要回去是何等的天壤之别啊！
7 .胸怀大局、四海一统的民族和外交政策，太宗朝的民族和外交政策取得了辉煌的胜利，四海之内只要知道中国的均努力内附，以唐为荣，乐不思蜀，他们不但同唐人一样可以自由自在的生存，还可以做官，著名的少数民族将领阿史那思摩、执思失力、契芯何力、黑齿常之、乃至后世的高仙芝、李光弼等都为唐朝做出了杰出贡献，在他们身上正好反映出李世民民族政策的光辉，现在的唐人、唐人街也正时那时繁荣富强、威甲四海、文礼之邦的生动写照；
8 .完善科举制度、大力兴办学校、重视教育活动、普及官吏选聘、当时的国子学、太学之盛、地方也有不少学校，如此才不难想起当时的教化呢，同时当时的科举也规范化、考选公平，以进士科最为杰出，如此才有太宗见新科进士鱼贯而出，喜言“天下英雄、入朕彀夷”，唐朝的教育及科举为政治上提供优秀人才同文化精髓——唐诗及经济发展做出杰出贡献；
9 .工书法、富文词，太宗皇帝个人修养及天赋极高，在书法同文词上也颇有名气，在他大力宏扬和鼓励支持下，才有唐代书法、文学、艺术之盛；
10 .倡导廉政、节俭、朴素、重视农田水利，太宗朝在廉政建设方面是相当成功的，他并没有像朱元璋一样严惩贪官污吏，而是建立一个廉洁奉公、遵纪守法的中央领导班子、重视地方长官选举，当时朝廷中不少卿相家境贫困，温彦博、戴胄、于志宁、魏征、张玄素等等，再加上良好风气的宣传和行政监督，及时预防了官员犯错，因此当时的官员相当奉公守法、廉洁自律；太宗皇帝也比较注意节俭，不滥用民力、注意与民休息，当时社会形成了一种朴素求实的作风；太宗皇帝也相当重视农业，京官外巡回京太宗先问及此事，因太子冠礼与农时违背而更改；
11 . 由于社会安定，商业经济得到发展，全国新兴了许多商业城市，城市业有相当的发展，广州、杭州、扬州、成都、江陵、凉州等城市经济发展相当迅猛，长安同洛阳作为世界经济大都会就不言而喻了，这为封建经济登顶奠定了坚实的基础；
12 .对玄奘佛学的支持同西游的肯定，打通并维护河西走廊－丝绸之路及东联新罗、日本，促进了中西文化交流与经济发展，文成公主下嫁吐蕃，使吐蕃从奴隶制社会迈入封建社会，开发并促进了西藏的发展；
综上所述，唐太宗李世民不愧为我国历史上一位伟大的政治家、书法家、卓越的领袖、影响中华乃至世界进程的杰出人物，他为中华民族同人民做出了杰出贡献，留下了辉耀千古的丰功伟业及精神财富，因此受到人们的崇敬；筑东阳先生所说“他是继孔子之后中国数一数二的伟人”。
【贞观之治】
贞观之治
形成原因
第一、隋朝政治制度和经济繁荣为唐朝加强中央集权和发展经济创造了条件；而隋炀帝暴政、奢侈腐化、奴役百姓、穷兵黩武，破坏社会生产，激化社会矛盾，导致农民起义。唐初统治者亲眼看到了农民战争瓦解隋朝的过程，认识到了广大农民对封建统治稳定的重要性，吸取隋亡教训，调整统治政策，以缓和阶级矛盾，稳定社会秩序，恢复经济。
第二、因为上述因素，唐太宗确定了“安百姓”、“重人才”、“强政治”的治国思想，并通过一系列的制度政策、措施和不懈的实践去实现。首先，唐太宗认识到了统治者与人民是“舟与水”的关系，通过土地赋税制度的调整以“安百姓”。二是认识到了重用人才，虚怀纳谏的意义，得人善任，从谏如流，营造出政治清明的氛围，保证了较为开明正确的政治、经济、民族、外交、文化上的政策得以制定和实施。三是加强政治，完善三省六部制和科举制，以巩固中央集权，提高行政效率，扩大统治基础。
注意：用人和纳谏，既是贞观之治出现的原因，又是贞观之治的重要表现。
在李世民统治其间，唐朝国力强盛，被称为贞观之治。晚年著《帝范》一书以教戒太子，其中总结了他一生的政治经验，也对自己的功过进行了评述。
他在位期间，推行府兵制、租庸调制和均田制，并积极推行科举制。
630年，击败东突厥，被突厥各部尊为“天可汗”。641年嫁文成公主给吐蕃的松赞干布。
649年，命太子李治到金液门代理国事。李世民于649年7月驾崩于长安含风殿，享年52岁，葬于今陕西礼泉东北50多里的山峰上的昭陵。谥号为“文皇帝”。
唐太宗善于听从大臣的批评和见解，魏征直谏200多次直陈他的过失。
唐太宗还精擅书法，以行书写碑，为后世鼻祖。著名作品有《温泉铭》《晋祠铭》等。死后更以东晋书法大家王羲之所作《兰亭集序》为陪葬品。
贞观之治是指唐朝初期出现的太平盛世。由于唐太宗能任人为贤，知人善用；开言路，虚心纳谏，重用魏征等；并采取了一些以农为本，减轻徭赋，休养生息，厉行节约，完善科举制等政策，使得社会出现了安宁的局面。与后来李隆基的“开元盛世”并肩而立。
唐太宗李世民在位23年，使唐朝经济发展，社会安定，政治清明，人民富裕安康，出现了空前的繁荣。由于他在位时年号为贞观，所以人们把他统治的这一段时期称为“贞观之治”。“贞观之治”是我国历史上最为璀璨夺目的时期。
太宗吸取隋朝灭亡的原因，非常重视老百姓的生活。他强调以民为本，常说：“民，水也；君，舟也。水能载舟，亦能覆舟。”太宗即位之初，下令轻徭薄赋，让老百姓休养生息。唐太宗爱惜民力，从不轻易征发徭役。他患有气疾，不适合居住在潮湿的旧宫殿，但他一直在隋朝的旧宫殿里住了很久。
贞观之初，在唐太宗的带领下，君臣和谐，全国上下一心，经济很快得到了好转。到了贞观八九年，牛马遍野，百姓丰衣足食，夜不闭户，道不拾遗，出现了一片欣欣向荣的升平景象。
太宗在位20多年，进谏的官员不下30余人，其中大臣魏征一人所谏前后200余事，数十万言，皆切中时弊，对改进朝政很有帮助。
太宗十分注重人才的选拔，严格遵循德才兼备的原则。太宗认为只有选用大批具有真才实学的人，才能达到天下大治，因此他求贤若渴，曾先后５次颁布求贤诏令，并增加科举考试的科目，扩大应试的范围和人数，以便使更多的人才显露出来。由于唐太宗重视人才，贞观年间涌现出了大量的优秀人才，可谓是“人才济济，文武兼备”。正是这些栋梁之才，用他们的聪明才智，为“贞观之治”的形成做出了巨大的贡献。
唐太宗十分注重法治，他曾说：“国家法律不是帝王一家之法，是天下都要共同遵守的法律，因此一切都要以法为准。”法律制定出来后，唐太宗以身作则，带头守法，维护法律的划一和稳定。在贞观时期，真正地做到了王子犯法与民同罪。执法时铁面无私，但量刑时太宗又反复思考，慎之又慎。他说：“人死了不能再活，执法务必宽大简约。”由于太宗的苦心经营，贞观年间法制情况很好，犯法的人少了，被判死刑的更少。据载贞观三年，全国判死刑的才29人，几乎达到了封建社会法制的最高标准——“刑措”即可以不用刑罚。
以民为本的思想，广开言路，虚怀纳谏的胸襟；重用人才，唯才是任的准则；铁面无私，依法办事的气度；构成了贞观之治的基本特色，成为封建治世最好的榜样。使唐朝在当时与西方国家相比，无论在政治、经济，还是文化上都走在世界的最前列。
一、社会秩序空前安定
史书记载：
贞观年间“官吏多自清谨。制驭王公、妃主之家，大姓豪猾之伍，皆畏威屏迹，无敢侵欺细人。商旅野次，无复盗贼，囹圄常空，马牛布野，外户不闭。又频致丰稔，米斗三四钱，行旅自京
[《贞观长歌》中的李世民(唐国强饰)]
《贞观长歌》中的李世民(唐国强饰)
师至于岭表，自山东至于沧海，皆不粮，取给于路。入山东村落，行客经过者，必厚加供待，或发时有赠遗。此皆古昔未有也”。
二、开放国境
由于东罗马帝国（395—1453）的衰落，西方变得支离破碎。到了隋朝时中国已经几欲是世界上最强大的国家了，而唐帝国尤其是贞观时期的唐朝更是当时世界唯一的文明最为强盛的大一统帝国，首都长安是世界性的大都会，各地民商来往不断，就象今天的美国纽约一样。那时的唐帝国是世界各国仁人志士心目中的“阳光地带”，各国的杰才俊士冒着生命危险也要往唐帝国跑。来自世界各国的外交使节纷纷赞叹唐朝的盛世，唐朝高度发展的文化，使来到唐朝的各国人，大多数以成为大唐人为荣。不仅首都长安，全国各地都有来自国外的“侨民”在当地定居，尤其是新兴的商业城市，仅广州一城的西洋侨民就有二十万人以上。贞观时期的唐王朝王朝是中国历史上少有的完全开放的王朝，比汉朝的仅限于贸易和传教还要开放，以至于各国各地的普通老百姓都可以来到唐朝一睹唐帝国的的风采，唐朝政府还在设立流所（和现在的使馆差不多），颇为开放边境和关口。极尽吸收外来文化和物质文明。
唐帝国除了接受大批的外国移民外，还接收一批又一批的外国留学生来中国学习先进文化，仅日本的官派的公费留学生就接收了七批，每批都有几百人。民间自费留学生则远远超过此数。这些日本留学生学成归国后，在日本进行了第一次现代化运动 ――“大化改新”，也就是中国化运动，上至典章制度，下至服饰风俗，全部仿效当时的贞观王朝，使处于原始部落状态的日本民族平空跃进了一千年。
日本民族并不高明，它只是善于学习而已。这个步子比别人慢半拍的民族有一个最大的优点――落后但不固执。当外来文明入侵时，它总是虚怀若谷地主动接受比本民族先进的文化，用最快最便捷的方式接受人类文明的先进成果，使自己快速跃进到先进民族的行列。
一个民族落后并不可怕，固执才是最可怕的！
三、政治清平
中国官场的贪污病菌是无孔不入的，以至占绝大多数的国人都认定贪污是人类社会的不治之症，只要是有“官”的地方就避免不了贪污。当从英美等国归来的留学生向他们的亲朋好友陈述这些国家基本上消灭了贪污时，没有几个人不认为他是在胡说八道。其实，贪污并不是人类社会的普遍现象，地球上就有不少文明程度较高的国家基本上消灭了贪污。不仅是美利坚和英吉利等现代化强国，就连主要由华人组成的新加坡也基本上消灭了贪污。
这里所说的基本上消灭了贪污并不是说完全杜绝了贪污现象，而是指贪污行为在整个官场中属极个别的现象，且贪污的数额不大（一年的贪污额一般不会超过此人一年的薪水），持续的时间也不会很长（连续作案三年以上的少之又少），都会很快败露且受到毫不留情的严惩。
贞观时期是中国历史上基本没有贪污的政治，这也许是李世民最值得称导的政绩。在李世民统治下的中国，皇帝率先垂范，官员一心为公，吏佐各安本份，滥用职权和贪污渎职的现象降到了历史上的最低点。尢为可贵的是：李世民并没有用残酷的刑罚来檠告贪污，主要是以身示范和制定一套尽可能科学的政治体制来预防贪污。在一个精明自律的统治者面前，官吏贪污的动机很小，贪官污吏也不容易找到藏身之地。防范贪污主要取决于一套科学修明的政治体制，光靠事后的打击只能取效于一时，不能从根子上铲除贪污赖以滋生的社会土壤。
四、分权制度
中国封建体制的主要特征是权力高度集中，地方服从中央，中央又唯皇帝马首是瞻。这种中央集权的政治体制极大地限制了国民的创造性、主动性和灵活性，且极易酿成暴政。
中国封建社会的中央政府组织实行“三省六部制”，但贞观王朝的三省职权划分则初步体现了现代化政治特征――分权原则。中书省发布命令，门下省审查命令，尚书省执行命令。一个政令的形成，先由诸宰相在设于中书省的政事堂举行会议，形成决议后报皇帝批准，再由中书省以皇帝名义发布诏书。诏书发布之前，必须送门下省审查，门下省认为不合适的，可以拒绝“副署”。诏书缺少副署，依法即不能颁布。只有门下省“副署”后的诏书才成为国家正式法令，交由尚书省执行。这种政治运作方式很有点类似现代民主国家的“三权分立” 制，西方在十七世纪兴起的分权学说，李世民早在一千多年前就已运用于中国的政治体制，进一步说明了贞观王朝的文明程度是何等之高。最为难能可贵的是，李世民规定自己的诏书也必须由门下省“副署”后才能生效，从而有效地防止了他在心血来潮和心情不好时作出有损他清誉的不慎重决定。中国历史上出了八百五十三个帝王，只有李世民一人拥有如此杰出智慧和胸襟（美国的开国总统华盛顿有点像他的学生）。
五、商业发达
中国封建王朝历来的经济特征是“重农抑商”，商业在国民经济中所占的比重相当低，商人的地位也因之比种田人要低好几个等次。这也是中国的封建经济一直得不到实质性发展的主要原因。
贞观王朝是中国历史上少有的不歧视商业的封建王朝，不但不歧视，还给商业发展提供了许多便利条件，这进一步地体现了李世民将眼光放到很远。在李世民政府的倡导下，贞观王朝的商业经济有了迅速和长足地进展，新兴的商业城市象雨后春笋般地兴起。当时世界出名的商业城市，有一半以上集中在中国。除了沿海的交州、广州、明州、福州外，还有内陆的洪州（江西南昌）、扬州、益州（成都）和西北的沙州、凉州。首都长安和陪都洛阳则是世界性的大都会。
自汉开辟的“丝绸之路” 一直是联系东西方物质文明的纽带，唐朝疆域辽阔，在西域设立了安西四镇，西部边界直达中亚的石国（今属哈萨克斯坦），为东西方来往的商旅提供了安定的社会秩序和有效的安全保障，结果丝稠之路上的商旅不绝于途，品种繁多的大宗货物在东西方世界往来传递，使丝稠之路成了整个世界的黄金走廊。
“贞观之治”总结
1 含义：在唐太宗统治时期，社会秩序比较安定，阶级矛盾相对缓和，经济繁荣，国力强盛。唐太宗的年号叫“贞观”，历史上把这一时期比较清明的封建统治称为“贞观之治”。
2 原因：1。隋唐更替，其间的战争是人口减少约2000万以上，战争结束，人少地多，人心思安，这是贞观之治产生的最重要原因。
2。隋开创了大运河以及科举，大运河的劳民导致隋灭亡，但这些却促成了贞观之治的产生。开创大运河，弊在当时，功在千秋。
3。前期的李世民汲取隋失败的教训，正如汉朝初期汲取秦灭亡的教训一样，让百姓休养生息，李世民自己也基本能虚怀从谏。但是，晚期的李世民变了，不再那么虚怀从谏，不在让百姓休养生息，而是好大喜功，征服高丽失败。这些是贞观之治不能持久的原因。
3 政绩：
第一，经济上实行均田制和租庸调制，使农民有可能安定生产，耕作有时，促进了经济的发展。
第二，政治上实行三省六部制和科举制。三省六部制的实行，使宰相的人数比秦汉时期增多，便于皇帝控制。
第三，唐太宗时期加强了国内汉族与少数民族的联系，加强对西北等地区的管辖，另外还加强了与亚洲各国的友好往来。
第四，唐太宗善于用人和纳谏，这既是“贞观之治”形成的原因之一，也是“贞观之治”的内容之一。他重用房玄龄、杜如晦、魏征、长孙无忌等能臣。
第五:重视农业,减轻农民赋税劳役."戒奢从简",节制自己的享受欲望;革除"民少吏多"的弊政,利于减轻人民的负担.
【天可汗之路】
唐朝是中国历史上一个最意气风发的时代，这个“大有胡气”的朝代中，边疆战争之频繁和战胜次数之多，在中国古代史上非常罕见。所以只有唐朝才能诞生专门的边塞诗派，诞生像“年年战骨埋荒外”这
样的诗句。而至于“汉家旌帜满阴山,不遣胡儿匹马还，愿得此生长报国，何须生入玉门关？”，“大漠风尘日色昏，红旗半卷出辕门。前军夜战洮河北，已报生擒吐谷浑”，“青海长云暗雪山，孤城遥望玉门关。黄沙百战穿金甲，不破楼兰终不还”，“葡萄美酒夜光杯，欲饮琵琶马上催。醉卧沙场君莫笑，古来征战几人回？”这种豪言壮语，则由于后世朝代偃武修文的风气，甚至成为了古代史上中国人尚武精神的绝响。尤其是贞观年间，大唐帝国四面出击，金戈铁马，气吞万里如虎。
第一个时期，唐太宗时期，全面扩张，四面出击。
贞观年间是唐朝拓边最猛烈的时期，也是获胜最大的时期。贞观年间，唐朝依次取得了对东突厥、吐蕃、吐谷浑、高昌、焉耆、西突厥、薛延陀、高句丽、龟兹甚至可能还包括印度用兵的胜利。这些胜利奠定了唐朝300年的基业。颉利可汗恐怕是有史以来第一个被中国军队活捉的草原帝国最高统治者。唐军出击定襄，痛歼突厥，活捉颉利可汗，也是唐朝历史上拓边战争中最辉煌的胜利。颉利可汗被抓到长安。突厥是唐朝最大的边患，作为同时存在的两个超级大国之一遭到毁灭，建立单极世界就变得容易多了。唐朝的另一个著名将领候君集奉命带兵修理骄横的吐蕃人。候君集通过夜袭击败了吐蕃军，斩首千余。吐蕃军退兵后，松赞干布做了颉利可汗也做过的事：派使者谢罪求和。但是他没有放弃和亲的请求。可能是被他的执着感动，7年后他的要求终于得到了满足。贞观十五年（641年），文成公主入藏。贞观八年(634)，吐谷浑犯唐，唐军再次远征，途中缺水，就刺马饮血，终于袭破可汗伏允的牙帐，伏允丢下老婆孩子溜之大吉，不久在沙漠中被部下所杀。吐谷浑从此被纳入唐朝的势力范围。贞观十三年，高昌国失臣礼。高昌王麴文泰看到唐兵来得那么快，吓得大病起来，感到忽冷忽热，几天后竟然一命呜呼，由此作为第一个被唐军活活吓死的人而载入史册。
第二个时期，征战高句丽
高句丽虽然向新成立的唐朝朝贡，但实际上却对唐朝持怀有敌视态度。到后来唐朝第二代皇帝唐太宗李世民的时候，为援助处于高句丽和百济围困中的新罗（《新唐书》：“（百济）与高丽联合伐新罗，取四十余城。发兵守之，又谋取棠项城，绝贡道”,新罗告急）,并统一被高句丽据有的辽东地区（当时的“辽东”的概念略同于汉朝四郡的范围，即中国东北辽河以东地区以及朝鲜半岛的北部），唐太宗征讨高句丽，放话给薛延陀：我们父子都要去打高句丽，长安空虚，你要是想犯贱只管放马过来！这么生猛的话，薛延陀当时就吓得气短了一截（《旧唐书》载后来高句丽用厚利诱惑薛延陀叛唐，但是“夷男气慑不敢动”）。
贞观十九年（645年），唐军向辽东进军。唐太宗在路上对手下人说，四方基本安定了，就剩下这一块地方了，趁着我还没死，良将们还有精力，一定要解决掉。
夏季，徐世绩暗渡陈仓，突然出现在辽东城下，高句丽士兵大骇。营州都督张俭和优秀将领李道宗也率兵进入辽东，击败高句丽兵，斩首数千。四月，唐军攻破高句丽盖牟城，俘虏两万多人，缴获粮食十多万石。五月，另一路唐军从山东渡海攻破高句丽卑沙城，俘虏八千人。上百年来中国军队第一次得以在鸭绿江边阅兵。
不久，李绩和李道宗所部进逼辽东城下。高句丽军数万来援。有人建议说高句丽军多唐军少，应该坚守。可是李道宗说高句丽人仗着人多以为我们不敢拿他们怎么样，我们就是要攻击他们，杀杀他们的锐气。李绩说我们被派来就是负责替皇上扫马路的。现在马路不干净，我们怎么能躲呢。于是唐军处于劣势却猛烈出击，高句丽兵始料不及，被冲乱阵型大败而归。唐太宗大军兵到后，把辽东围得水泄不通，日夜攻打。乘着刮南风的机会，唐太宗指挥士兵点燃城池西南楼，顺风放火。高句丽军抵挡不住了，辽东陷落。唐军杀高句丽兵一万多人，俘虏一万多人，此外还有百姓四万多人。
攻克辽东后，唐军继续向白岩城进发。乌骨城派兵一万支援，被唐军击退（此战唐军只用了800 人）。六月，白岩城不战而降。唐军继续向安市进发。高句丽将领高延寿等人率领靺鞨、高句丽兵十五万来救援，被击败。高延寿向唐军乞降，来到唐军军营，一进门就跪下，挪动膝盖向前，拜伏在地。（《资治通鉴》上说“延寿、惠真帅其众三万六千八百人请降，入军门，膝行而前，拜伏请命。”）唐太宗对他们说：“东夷少年，跳梁海曲……自今复敢与天子战乎？”高延寿等人“皆伏地不能对”。唐太宗将降军中的高句丽军官、酋长三千余人虏往中原，其余高句丽人悉数释放。
安市城小而坚，在城主杨万春的抵抗下，唐军围攻数月不克。长孙无忌以为：‘天子亲征，异于诸将，不可乘危徼幸。今建安、新城之虏，众犹十万，若向乌骨，皆蹑吾后，不如先破安市，取建安，然后长驱而进，此万全之策也。’”）而这种方式过去一直是唐军克敌制胜的法宝。最终唐太宗决定暂时停止这次出征。9月，唐军班师。这次征伐高句丽，攻克玄菟、横山、盖牟、磨米、辽东、白岩、卑沙、麦谷、银山、后黄十城，迁徙辽、盖、岩三州户口入中国七万人。新城、建安、驻跸三大战，斩首四万余级。在唐军，战士阵亡的约2000人，损失最大是战马，损失了七八成。
此战虽重创高句丽，但是战事旷日持久，耗费巨大，最终却未能灭亡高句丽。因此，唐太宗认为这战属于战败了，痛心地说：如果魏征还活着，肯定不会让我进行这次远征。但这战的意义还是比较重大的。这是自三国时期毋丘俭攻破高句丽屠王城以来上百年中国军队第一次真正战胜高句丽人，收复了今天辽宁一带很多南北朝时期被高句丽夺取的土地，为今后唐朝彻底征服朝鲜打下了基础。
贞观二十二年（648年），倒是有个印度的小插曲。王玄策作为唐朝的使者去印度。中天竺大臣那伏帝阿罗那顺篡位，劫持唐使。王玄策只身逃到吐蕃，借来吐蕃军和尼泊尔军向印度进发。连战三天，印度军大败。唐军斩首三千余级，水中淹死印度兵约万人。阿罗那顺弃城逃跑，副使蒋师仁追上并俘虏之。此外虏男女一万二千人，牛马三万余匹。
【地缘战略思想】
唐太宗地缘战略思想，是唐太宗关于地缘战略问题的理性认识，是唐太宗利用唐王朝与周边少数民族政权之间的地缘关系及其作用法则谋取和维护唐王朝利益的战略思想。唐太宗地缘战略思想是中国古代地缘战略思想的重要组成部分，既有不同于西方也不同于现代的独具特色的思想内容。
唐太宗在位期间国土广大，边界线绵延曲折，地缘形势复杂，并随时间推移而发展变化。历观这一时期唐与周边所发生的诸多地缘关系，既有与唐军事利益攸关的，也有与唐政治、外交利益攸关的，还有与唐经济利益攸关的，更多的则是几种利益兼而有之，错综复杂。唐太宗比较成功地处理了与突厥、吐蕃、高昌及西域诸国、高丽、新罗、百济等国之间的关系。唐太宗的地缘战略思想正是在处理与周边地缘关系的实践过程中逐步产生、发展并走向成熟的。
唐太宗地缘战略思想既具有鲜明的时代特色，又具有他个人的独有特色，两者巧妙地融合在一起，贯穿于他的地缘战略思想的始终。
唐太宗地缘战略思想的特色主要有以下几点：一是积极进取。这是唐太宗地缘战略思想的最显著的特色，也是其思想中最成功、最可取的地方。唐太宗的雄大豪迈是历代许多帝王所不可比拟的，这也是他取得成功不可或缺的因素。二是灵活应对。唐太宗在重大变故面前不惊慌失措，他能够依据客观形势和对象的变化而变化，从而较大程度地保证了决策的正确性。三是冷静务实。唐太宗鉴于隋亡教训，努力克服以往帝王急功近利、穷兵黩武的缺陷，注意结合现实需要，量力而行，在冷静分析的基础上推行务实政策。四是措置有序。无论是北击突厥，还是西平高昌，尤其是经略西域，都是先急后缓、由近及远，有条理、有次序地进行，从中亦可见唐太宗地缘战略决策之成熟。
唐太宗地缘战略思想是其军事思想的重要组成部分，不仅在理论上取得了突破，达到了一个新高度，更重要的是在实践中获得巨大成功，业绩斐然。史载：“（贞观十四年）唐地东极于海，西至焉耆，南尽林邑，北抵大漠，皆为州县，凡东西九千五百一十里，南北一万九百一十八里。”（《资治通鉴》唐太宗贞观十四年九月。）唐太宗的突出成就正在于他以超越前人的英武雄迈之气魄，重新开拓了中华民族的疆土，为后来中国版图的确定作出了重大的贡献。而这一辉煌业绩的获得，是与唐太宗的地缘战略思想密切不可分的。即使今天看来，唐太宗的地缘战略思想里面也不乏可取之处。
唐太宗地缘战略思想包含丰富的内容，主要有以下几点：
（一）着眼于争夺关中、巩固“中国”的固本思想。其中居重驭轻的关中本位思想，乃是唐太宗成就帝业的“根本”，也是其地缘战略思想的出发点。 太宗“深根固本，治安中国”之思想，既有传统政策沿袭之因素，又有出于当时初唐政治、经济背景考虑之因素，特别是对地缘因素的考虑，为巩固政权、密切中外关系、发展经济进而增强国力而不得不为之。
（二）以夷制夷、保藩固圉的地缘藩屏思想，主要体现在以“怀辑”政策绥纳归附民族，并将其内徙安置在唐周边地区的一系列行为上，从而达到令其“世作藩屏”的目的。
唐太宗的地缘藩屏思想主要有如下两个内容：
１置内属少数民族政权于周边，以作藩屏。
２在唐周边地区扶植亲唐政权，以作藩屏。
（三）纵横捭阖的地缘制衡思想。
其主要内容有：①远交近攻，各个击破，如联薛延陀制突厥。②扶弱抑强，保持地区势力均衡，如联新罗攻高丽、百济以及联合铁勒诸部扼制薛延陀。③联近抗远，服近慑远，稳定近邻以攻击或威慑远方政权，如联合吐谷浑以对付吐蕃。④另外，唐太宗还有针对某一特定政权内部制定的制衡思想，旨在分化瓦解其势力，造成内部争权夺利，削弱统治实力，这尤其体现在对薛延陀的问题上。
唐太宗实行地缘制衡的策略思想及其基本情况大致有如下几种：
１远交近攻，拉拢与孤立并用——唐与东突厥、 薛廷陀的地缘制衡关系。
２扶弱抑强，保持地区均势。
【太宗争议】
我们都知道，李世民也是人，人无完人，是人就有错误。贞观后期，唐太宗开始有了一些变化，先从纳谏开始体现出来。贞观十年（636年），魏征发现他“渐恶直言”，这是唐太宗走向一些错误的开始。
一是征伐高句丽，这个被某些人认为是错误的举动，但是，就当时形势来看，此征是必要的和需要的。第一，发动战争的责任是高句丽，高句丽悍然进攻唐朝附庸国新罗挑起战端，为了维护权威，唐需要发动战争来保护自己的附属国的利益。第二，战争中，唐军是正义和人性的，这也是保证唐军损失非常小的一个外在条件，在唐军攻占的城池中，均拥护唐军。但是由于为了保持正义性和人性化，导致偏求稳，而使战期拉长。第三，唐军的撤退和后续战争，充分体现了李世民的胸怀和高超的战略思想，唐军以2000人的损失消灭高句丽数十万人，千古罕见。撤退之时，敌将城墙跪拜，也实属罕见。唐军后期的军事骚扰和政治封锁，使高句丽的实力每况愈下，最终高宗消灭高句丽。
还有奢侈现象的明显增加。在贞观十六年的时候，唐太宗下诏说，太子所用之物其他机关不得限制，结果造成太子的严重浪费现象。唐太宗自己也开始修造宫殿，贞观十一年在东都洛阳修飞山宫，二十一年又修翠微宫。这些使唐太宗后期没有前期勤俭，但是比玄宗，乾隆等不知道要强多少倍。
还有一个大的错误就是参与史官所写的起居注当中。这是专门写皇帝日常生活和朝政言论的，皇帝无权干涉，这是历来的传统，历来的皇帝都没有看，尊重史官的职权和地位。而史官也是公正直书，从不掩饰什么，从不害怕皇帝打击报复。但唐太宗这个名君却犯了一个颇大的历史错误，影响干预了史官的公正性。当然，没有任何完整证据表明太宗大量歪曲历史。同时，不仅仅是太宗，自春秋，看史者何止数百，董狐直笔，陈寿索贿，太史被宫，不要说清朝的文字狱了，另外，许敬宗对李世民并没有好感，这样表明，唐初历史应该具有可信度的。
唐太宗在贞观初期不顾大臣魏征和李大亮的劝阻，对归顺的北方游牧民族部落要土地给土地要物资给物资，结果这些部落享受够唐朝的恩惠后胃口反而越来越大，索性就叛乱了。
后来唐太宗也自己检讨：“中国百姓，实天下之根本，四夷之人，乃同枝叶，扰其根本以厚枝叶，而求久安，未之有也。初不纳魏征言，遂觉劳费日甚，几失久安之道。”
贞观二十年（646年），辽东战役回来时，唐太宗得病，此后一直调养，由此开始服用方士提炼的金石丹药。先前唐太宗还曾经嘲笑秦皇汉武迷恋方术和寻求丹药，现在自己也不由自主地陷进去了。贞观二十一年（647年），唐太宗又得了“风疾”，烦躁怕热，便让人在骊山顶峰修翠微宫，第二年，派人从中天竺求得方士那罗迩娑婆寐，病情不断恶化。贞观二十三年（649年）五月己巳（二十六）日（7月10日）驾崩于含风殿，享年五十二岁。
【后妃子女】
皇后
长孙皇后
唐朝著名的贤后，中国历史上最伟大的皇后之一，当代历史学家评论最知性的皇后。秦王妃期间，众臣属就莫不感激，在皇后位，治理后宫井井有条，对贞观政策路线颇有影响，早逝，太宗皇哀伤不已，常举目远眺昭陵，自后未再立皇后，皇后生幼子幼女晋王和晋阳公主被太宗亲自带在身边抚养，太宗崩，与皇后同葬一穴，开创帝后合穴先例。
有人说：一个伟大的男人背后站着一个伟大的女性。唐太宗大治天下，盛极一时，除了依靠他手下的一大批谋臣武将外，也与他贤淑温良的妻子长孙皇后的辅佐是分不开的。
妃嫔
韦贵妃 字泽
杨贵妃 杨妃，生赵王李福，为与隋炀帝女杨妃区别被现代人称小杨妃，贵妃应为死后追封。
徐贤妃 徐惠，帝崩，哀慕成疾，不肯进药，曰：“帝遇我厚，得先狗马侍园寝，吾志也。”复为诗、连珠以见意。永徽元年卒，年二十四，赠贤妃，陪葬昭陵石室。
燕德妃 燕妃
杨妃 隋炀帝女
阴妃 后降为嫔
韦昭容 韦尼子
杨婕妤 杨恭道第三女
萧美人 萧铄第二女
崔才人 崔宏道长女
萧才人 萧铿第二女
武才人 武则天
杨氏 李元吉之妻
王氏
子
太子李承乾（母长孙皇后,太宗皇子中最为彪悍聪颖者，因谋反被废）
楚王李宽（母不详，早薨）李宽，过继叔父楚哀王李智云。早逝。贞观初追封，无后，国除。
吴王李恪（母隋炀帝之女杨妃）有文武才，唐高宗时期被冤杀。
魏王李泰（母长孙皇后，太宗皇子中最为博学者，最受宠爱者，因争皇位被贬，高宗年间备受尊崇）（619年―652年）字惠褒，永徽三年（652年）死于郧乡县，时年34岁。
齐王李佑（母阴妃，后废为庶人）
蜀王李愔（母隋炀帝女杨妃，李恪同母弟，李世民称其不如禽兽。李恪被害，徙居巴州。）
蒋王李恽（母王氏）
越王李贞（母燕妃）
高宗李治（原为晋王，母长孙皇后，皇子中唯一被太宗亲自抚养长大者）
纪王李慎（母韦妃）
江殇王李嚣（母燕妃，早薨）
代王李简（母不详，早薨）
赵王李福（母杨妃）
曹王李明（母杨氏）
女
襄城公主
汝南公主 李宇
南平公主
遂安公主
长乐公主 李丽质（母长孙皇后，出嫁时因太宗要给的嫁妆倍于长公主而被魏征谏）
豫章公主（长孙皇后养女）
巴陵公主（下嫁柴令武），下嫁柴绍与平阳公主之子柴令武，永徽四年与房遗爱谋反，被唐高宗赐死。显庆中追赠为北景公主
普安公主
东阳公主
临川公主 李孟姜（母韦贵妃）
清河公主 李敬
兰陵公主 李淑
晋安公主
安康公主（关于安康公主，唐史只有一句话：“安康公主，下嫁独孤谋。”）
新兴公主
城阳公主（母长孙皇后）
高阳公主（合浦公主）
金山公主
晋阳公主 李明达（母长孙皇后，公主中唯一被太宗亲自抚养长大者，为太宗最为喜爱的女儿，多受众臣喜爱，早薨，有其母风）
常山公主
新城公主（母长孙皇后，初封衡山公主）
【主要诗作】
【赐房玄龄】
太液仙舟迥，西园引上才。未晓征车度，鸡鸣关早开。
【赐萧瑀】
疾风知劲草，板荡识诚臣。勇夫安识义，智者必怀仁。
【辽城望月】
玄菟月初明，澄辉照辽碣。映云光暂隐，隔树花如缀。
魄满桂枝圆，轮亏镜彩缺。临城却影散，带晕重围结。
驻跸俯丸都，伫观妖氛灭。
【饮马长城窟行】
塞外悲风切，交河冰已结。瀚海百重波，阴山千里雪。
迥戍危烽火，层峦引高节。悠悠卷旆旌，饮马出长城。
寒沙连骑迹，朔吹断边声。胡尘清玉塞，羌笛韵金钲。
绝漠干戈戢，车徒振原隰。都尉反龙堆，将军旋马邑。
扬麾氛雾静，纪石功名立。荒裔一戎衣，灵台凯歌入。
【经破薛举战地】
昔年怀壮气，提戈初仗节。心随朗日高，志与秋霜洁。
移锋惊电起，转战长河决。营碎落星沉，阵卷横云裂。
一挥氛沴静，再举鲸鲵灭。于兹俯旧原，属目驻华轩。
沉沙无故迹，减灶有残痕。浪霞穿水净，峰雾抱莲昏。
世途亟流易，人事殊今昔。长想眺前踪，抚躬聊自适。
【还陕述怀】
慨然抚长剑，济世岂邀名。星旂纷电举，日羽肃天行。
遍野屯万骑，临原驻五营。登山麾武节，背水纵神兵。
在昔戎戈动，今来宇宙平。
【出猎】
楚王云梦泽，汉帝长杨宫。岂若因农暇，阅武出轘嵩。
三驱陈锐卒，七萃列材雄。寒野霜氛白，平原烧火红。
雕戈夏服箭，羽骑绿沉弓。怖兽潜幽壑，惊禽散翠空。
长烟晦落景，灌木振严风。所为除民瘼，非是悦林丛。
【元日】
高轩暧春色，邃阁媚朝光。彤庭飞彩旆，翠幌曜明珰。
恭己临四极，垂衣驭八荒。霜戟列丹陛，丝竹韵长廊。
穆矣熏风茂，康哉帝道昌。继文遵后轨，循古鉴前王。
草秀故春色，梅艳昔年妆。巨川思欲济，终以寄舟航。
【喜雪】
碧昏朝合雾，丹卷暝韬霞。结叶繁云色，凝琼遍雪华。
光楼皎若粉，映幕集疑沙。泛柳飞飞絮，妆梅片片花。
照璧台圆月，飘珠箔穿露。瑶洁短长阶，玉丛高下树。
映桐珪累白，萦峰莲抱素。断续气将沉，徘徊岁云暮。
怀珍愧隐德，表瑞伫丰年。蕊间飞禁苑，鹤处舞伊川。
傥咏幽兰曲，同欢黄竹篇。
【编年纪事】
贞观元年（六二七）正月初一，改元贞观。
贞观元年（六二七）正月，唐太宗下制，令今后中书省、门下省以及三品以上官入阁商议国家大事，都要有谏官跟随，遇有不当之处，谏官立刻进谏。
贞观元年（六二七）正月，唐太宗命吏部尚书长孙无忌等与学士、法官等人重新议定律令。放宽绞刑五十条为砍断有趾，唐太宗仍嫌这种肉刑太残酷，蜀王法曹参军裴弘献请再改为加役流，徙三千里，居作三年。诏从之。
贞观元年（六二七）唐天节将军、燕郡王李艺据泾州反。
贞观元年（六二七）二月，并省全国的州县，将全国分为十道，即关内道、河南道、河东道、河北道、山南道、陇右道、淮南道、江南道、剑南道、岭南道，废郡为州，故每道各辖若干州。
贞观元年（六二七）十月岭南酋长冯盎遣子入朝
贞观元年（六二七）末，吏部侍郎刘林甫奏请以后四时听选，随阙注拟，人以为便。太宗诏命一部分人到洛州参选。太宗说“官在得人，不在员多。”命房玄龄并省中央官员，只留下文武官额六百四十三人。
贞观二年（六二八），诏各地置义仓。薛延陀首领夷男受唐封为可汗，建汗庭于漠北。
贞观二年（六二八）三月，大理少卿胡演向太宗上报每月囚徒的账目。太宗命令后大辟罪由中书、门下省四品以上官和尚书省议定，以免冤滥。接着又逐个带进囚徒，轮到岐州刺史郑善果时，太宗认为善果虽有罪，官品不低，不应与于囚徒之列。于是，又命以后三品以上官犯罪，不用带进，可在太极宫承天门左右朝堂听判决。
贞观二年（六二八），关内发生旱灾，百姓缺粮，有许多人卖儿卖女以换取衣粮。四月，太宗诏出御府金帛赎回被卖儿童，交还父母。又因去年久雨，今年又遭受旱灾、蝗灾，大赦天下。
贞观二年（六二八）四月，突利派使来唐请求援助。太宗召集大臣讨论，兵部尚书杜如晦请出兵攻突厥。贞观三年（六二九）十二月，突利可汗入朝，太宗任命他为右卫大将军，赐爵北平郡王。
贞观二年（六二八）九月，中书舍人李百药请再出宫人。唐太宗命尚书左丞戴胄和给事中杜正伦在掖庭西门简选宫人，前后放出宫女又达三千余人。
贞观二年（六二八）末，派遣游击将军乔师望从小路带着册书拜夷男为真珠毗伽可汗，赐给他鼓纛。夷男非常高兴，派使入贡。
贞观三年（六二九）三月，太宗以房玄龄为左仆射，杜如晦为右仆射，以尚书右丞魏征守秘书监，均参与朝政。房玄龄善谋略，杜如晦善决断，为唐朝名相，并称“房杜”。
唐朝初年，凡国家军政大事，中书舍人各依自己的见解，签署自己的名字，被称做五花判事。由中书侍郎、中书令审查，由给事中、黄门侍郎校正。贞观三年（六二九）四月，唐太宗重新申明旧的制度，于是很少发生错事。
贞观三年（六二九）大旱，太宗诏求直言，常何代马周向太宗提了二十多条意见。太宗大喜，招马周入见，令他宿直门下省，不久以马周为监察御史，终至拜相。
贞观三年（六二九）八月，命兵部尚书李靖为行军总管、张公谨为副总管，前去征讨突厥。突厥俟斤九人带领三千骑兵降唐，拔野古、仆骨、奚等酋长也帅部众降唐。
贞观三年（六三〇）闰十二月，东谢酋长谢元深、南谢酋长谢强朝唐。东谢、南谢是南蛮的分支，分布在黔西。唐太宗下诏以东谢之地为应州（今贵州德江县贞观三年（六三〇）闰十二月，牂牁酋长谢能羽及兖州蛮向唐入贡。太宗诏以牂牁之地为牂州。党项酋长细封步赖降唐，唐以其地为轨州境），南谢之地为庄州（今贵州境内），隶属于黔州都督
贞观四年（六三〇）正月，李绩在白道败突厥，李靖在阴山大败颉利可汗。
贞观四年（六三〇）正月，李靖率三千骑自马邑进驻恶阳岭，夜袭定襄，大败突厥。颉利可汗大惊，迁牙帐于碛口。颉利的亲信康苏密以隋炀帝后萧氏及其孙杨政道降唐。
贞观四年（六三〇）三月，各族君长都到长安请唐太宗称天可汗，唐太宗笑道：“我为大唐天子，难道又为可汗之事吗？”但此后唐太宗赐给西北各族君长的玺书都用“天可汗”的称号。
贞观四年（六三〇）三月，唐行军副总管张宝相突至苏尼失兵营，俘颉利，送往长安。
贞观四年（六三〇）九月，伊吾城主到长安朝唐。先是伊吾内属，隋于其地设置伊吾郡；隋末，城主向突厥称臣。颉利被唐攻灭后，伊吾城主率他所属的七城降唐，唐朝在伊吾设置西伊州（今新疆哈密）。
太宗阅读中医著作《明堂针灸书》后，认为人的五脏都归结在背部。于是于贞观四年（六三〇）十一月下令，此后审讯犯人，不得鞭击背部。
贞观四年（六三〇），全国丰收，流散到各地的百姓回归故里，米每斗不超过三、四钱，一年仅判处了二十九人死刑。
贞观四年（六三〇）八月，日本遣使犬上三田耜（亦作御田锹）、药师惠日等来唐，是为日本第一次遣唐使。
贞观五年（六三一），开党项之地为十六州。日本第一次遣唐使犬上御田锹等至唐（奉使在上年）。林邑、新罗都遣使到唐。
贞观五年（六三一）十二月初二日，唐太宗制：“判决死罪，要在两天内五次申奏，下各州的要三次申奏；行刑当天，尚食局不得进酒肉，内教坊及太常寺不得奏乐。门下省还要再检查，有依法应当死而处境堪怜者，另外写状上奏。”五次申奏是指行刑前两天到行刑之日共上奏五次，人命关天，以示慎重。只有犯恶逆罪（隋立“十恶不赦”之科，唐承之）的人只奏一次。
贞观六年（六三二），太宗乃止。增置三师官（太师、太傅、太保）。太宗与侍臣论安危之本。长孙后贺太宗喜得谏臣，焉耆王遣使入贡，唐太宗派鸿胪少卿刘善因前去册立泥孰为奚利邲咄陆可汗。
贞观六年（六三二）十一月，契苾（铁勒十五部之一）部落酋长契苾何力率所部六千余家到沙州（今甘肃敦煌西）向唐政府归降。
贞观七年（六三三），太宗赦死囚，李淳风造浑天黄道仪。
贞观八年（六三四），李靖等赴诸道察情。
贞观九年（六三五），唐高祖李渊驾崩，享年70岁，唐平吐谷浑。
贞观十年（六三六），唐建南北衙。
贞观十年（六三六）六月二十一日，太宗皇后长孙氏卒，享年三十七岁。
贞观十一年（六三七）八月，侍御史马周上疏朝廷，建议政府应重视州县地方官吏的选任。太宗闻奏，深以为是，决定以后刺史由他亲选，县令则由京官五品以上各举一人。
贞观十二年（六三八）立薛延陀小可汗，太宗建百骑。
贞观十三年（六三九）太宗停世袭刺史。
贞观十四年（六四〇）流鬼国遣使入贡， 侯君集灭高昌，唐置安西都护府于交河，礼官改礼制，唐文成公主入藏。
贞观十五年（六四一）唐蕃和亲，席君买平吐谷浑之乱，册封百济王，李世绩败薛延陀。
贞观十六年（六四二）魏王泰上《括地志》，太宗徙死罪者实西州，禁自伤肢体，郭孝恪败西突厥咄陆可汗。
贞观十七年（六四三）魏征卒，享年64岁。征高句丽，李世民命画功臣像于凌烟阁，太子李承乾造反，被废，立晋王李治为皇太子。
贞观十八年（六四四）太宗亲征高句丽。
贞观十九年（六四五）铁勒九姓大首领率众降唐。 玄奘取经回国，张亮、程名振拔高丽卑沙城，李世绩攻高丽辽东城，契苾何力等勇击高丽，高丽白岩城降，太宗破高丽安市救兵，太宗下诏从高丽班师。
贞观二十年（六四六） 薛廷陀咄摩支降唐，敕勒诸部朝唐。
贞观二十一年 （六四七）唐发兵攻龟兹，太宗哭高士廉，骨利干入贡，王波利造船攻高丽，突厥车鼻可汗向唐朝入贡，西赵酋长赵磨内附。
贞观二十二年（六四八）薛万彻等率军击高丽，李百药卒，结骨入朝，松外蛮附唐，契丹首领曲据内附，阿史那贺鲁降唐，王玄策破中天竺，房玄龄病逝，享年70岁。
贞观二十三年 （六四九）徒莫祗等蛮内附。
贞观二十三年（六四九）五月，唐太宗病危。临终前，他召见长孙无忌和褚遂良，让他们辅佐太子治听政。同月己巳日，太宗驾崩于翠微宫含风殿，享年52岁。太子李治即位，是为唐高宗。他是历史上最为伟大的皇帝之一。
【太宗丞相】
萧瑀(626年，627年，630年，643年-646年)
陈叔达(626年)
封德彝(626年-627年)
宇文士及(626年-627年)
高士廉(626年-627年，638年-647年)
房玄龄(626年-643年，643年-648年)
长孙无忌(627年-628年，645年-649年)
杜淹(627年-628年)
杜如晦(628年-629年)
李靖(628年-634年)
王珪(628年-633年)
魏征(629年-643年)
温彦博(630年-637年)
戴胄(630年-633年)
侯君集(630年-632年，632年-643年)
杨师道(636年-643年，645年)
刘洎(639年-645年)
岑文本(642年-645年)
李世绩(643年-649年)
张亮(643年-646年)
马周(644年-648年)
褚遂良(644年-647年，648年-649年)
许敬宗(645年)
高季辅(645年)
张行成(645年)
崔仁师(648年)
In 630, Emperor Taizong sent his general Li Jing against Eastern Tujue -- 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 eastern Asia, and Emperor Taizong subsequently took the title of "Heavenly Khan" (天可汗). 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 Zhen'guan" (貞觀之治) was considered one of the golden ages of Chinese history and became required study for future crown princes. Indeed, the greatest praise that one of his better-regarded successors, Emperor Xuānzong, received, was the epithet "Little Taizong" (小太宗). The modern Chinese historian Bo Yang, for example, opined that Emperor Taizong achieved his greatness by accepting criticism that others would find difficult to accept and trying hard not to abuse his absolute power (using Emperor Yang of Sui as a negative example as well as employing the capable chancellors Fang Xuanling, Du Ruhui, and Wei Zheng. Bo also opined that Emperor Taizong's wife Empress Zhangsun served as a capable assistant to him as well.
Background
Li Shimin 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. 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 (太原, in modern Taiyuan, Shanxi), 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).
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 it 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.
However, when Li Yuan arrived near Hedong, his army was bogged down by the weather, and 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 sizeable 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, he captured Chang'an 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 Sui territory 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 rapproachment, 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 Jin'gang (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 (襄陽, in modern Xiangfan, Hubei), 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 corner, 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, clad in black uniform and black armor, commanded by himself, to serve as advance forward troops, with Qin, Cheng Zhijie (程知節), Yuchi, and Zhai Zhangsun (翟長孫) as his assistants.
Main article: Battle of Hulao
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. 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
Main article: Incident at Xuanwu Gate
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 Jianheng'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. Lli 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 (樊城, also in modern Xiangfan), 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).
Early reign
One of the first actions that Emperor Taizong carried out as emperor was releasing a number of ladies in waiting from the palace and returning them to their homes, so that they could be married. He created his wife Princess Zhangsun as empress, and their oldest son Li Chengqian as crown prince.
Emperor Taizong was also immediately faced a crisis, as Eastern Tujue's Jiali Khan Ashina Duobi, along with his nephew the subordinate Tuli Khan Ashina Shibobi (阿史那什鉢苾), launched a major incursion toward Chang'an, and just 19 days after Emperor Taizong took the throne, the two khans were just across the Wei River from Chang'an. Emperor Taizong was forced to, accompanied by Gao Shilian and Fang Xuanling, meet Ashina Duobi across the river and personally negotiate peace terms, including tributes to Eastern Tujue, before Ashina Duobi withdrew.
Late in 626, Emperor Taizong ranked the contributors to Tang rule and granted them titles and fiefs, naming among the first rank of contributors Zhangsun Wuji, Fang, Du Ruhui, Yuchi Jingde, and Hou Junji. When Li Shentong, as his distant uncle, objected to being ranked under Fang and Du, Emperor Taizong personally explained how Fang and Du's strategies allowed him to be successful, and this managed to get the other objectors to quiet down, as Emperor Taizong was even willing to rank low such an honored individual as Li Shentong. Emperor Taizong also buried Li Jiancheng and Li Yuanji with honors due imperial princes and had their staff members attend the funeral processions. Meanwhile, he appeared to began to reshuffle government further -- which he had already begun after being created crown prince -- by dismissing his father's trusted advisors Xiao Yu and Chen Shuda, making his own trusted advisors chancellors. (Xiao, however, was soon restored to being chancellor, although his career during Emperor Taizong's reign would see repeated dismissals and repeated restorations.) However, he also began to greatly pay attention to the officials' submissions and their criticism of imperial governance, making changes where he saw needed. He also particularly began to trust Wei Zheng, accepting much advice from Wei as far as his personal conduct was concerned. He was also willing to demote his own trusted advisors, as he demoted Gao after finding that Gao had held back submissions from his deputy Wang Gui. Viewing Sui's Emperor Yang as a negative example, he frequently solicited criticism, rewarding those officials willing to offer them, particularly Wei and Wang Gui.
Also in 627, the general Li Yi the Prince of Yan -- a late-Sui warlord who later submitted to Tang, who associated with Li Jiancheng -- fearing that Emperor Taizong would eventually take action against him, rebelled at Bin Prefecture (豳州, in modern Xianyang), but was quickly crushed by the official Yang Ji (楊岌) and killed in flight. Later that year, when Emperor Gaozu's cousin Li Youliang (李幼良) the Prince of Changle, the commandant at Liang Prefecture (涼州, roughly modern Wuwei, Gansu), was accused of allowing his staff to oppress the people and to trade with Qiang and Xiongnu tribesmen, Emperor Taizong sent the chancellor Yuwen Shiji (Yuwen Huaji's brother) to investigate, and in fear, Li Youliang's staff members plotted to hold him hostage and rebel. When this was discovered, Emperor Taizong forced Li Youliang to commit suicide. Late in the year, Wang Junkuo (王君廓), the commandant at You Prefecture (幽州, roughly modern Beijing), also rebelled, but was defeated quickly and killed in flight. However, although there were also reports that Feng Ang (馮盎), a warlord in the modern Guangdong region, was rebelling, Emperor Taizong, at Wei's suggestion, sent messengers to comfort Feng, and Feng submitted.
Also in 627, Emperor Taizong, seeing that there were too many prefectures and counties, consolidated and merged many of them, and further created another level of local political organization above prefectures -- the circuit (道, dao) -- dividing his state into 10 circuits.
In 628, with Ashina Duobi and Ashina Shibobi having a fallout, Ashina Shibobi submitted to Emperor Taizong, as did the chieftains of Khitan tribes, who had previously submitted to Eastern Tujue. With Eastern Tujue in turmoil, Ashina Duobi was no longer able to protect the last late-Sui rebel ruler who along remained standing against Tang pressure -- Liang Shidu the Emperor of Liang, and in summer 628, with the Tang generals Chai Shao and Xue Wanjun (薛萬均) sieging the Liang capital Shuofang (朔方, in modern Yulin, Shaanxi), Liang Shidu's cousin Liang Luoren (梁洛仁) killed Liang Shidu and surrendered, finally uniting China. With Eastern Tujue weakened, Eastern Tujue's vassal Xueyantuo also broke away and formed its own khanate, and Emperor Taizong entered into an alliance with Xueyantuo's leader Yi'nan (夷男), creating Yi'nan the Zhenzhupiqie Khan (真珠毗伽可汗, or Zhenzhu Khan in short).
In late 629, believing the time ripe for a major attack on Eastern Tujue, Emperor Taizong commissioned the general Li Jing with overall command of a multi-pronged army, assisted by the generals Li Shiji, Chai, and Xue Wanche (薛萬徹, Xue Wanjun's brother), attacking Eastern Tujue at multiple points. The army was successful in its attacks, forcing Ashina Duobi to flee, and by late spring 630, Ashina Duobi had been captured, and Eastern Tujue chieftains all submitted to Tang. Emperor Taizong spared Ashina Duobi but detained him at Chang'an, and he considered what to do with the Eastern Tujue people. The main opposing views were from the chancellors Wen Yanbo (who advocated leaving the Eastern Tujue people within borders to serve as a defense perimeter) and Wei (who advocated leaving them outside the borders). Emperor Taizong accepted Wen's suggestion and established a number of prefectures to accomodate the Eastern Tujue people, still leaving them governed by their chieftains, without creating a new khan to govern them.
In 631, Emperor Taizong established a feudal scheme, where the contributors to his reign were given, in addition to their current posts, additional posts as prefectural governors, to be passed on to their descendants. Soon, however, receiving much opposition to the plan, the strongest of which came from Zhangsun Wuji, Emperor Taizong cancelled the scheme.
After the conquest of Eastern Tujue, Emperor Taizong's officials repeatedly requested that he carry out sacrifices to heaven and earth at Mount Tai, and Emperor Taizong, while at times tempted by the proposal, was repeatedly dissuaded from doing so by Wei, who pointed out the expenses and the labors that would be imposed on the people as a result, and also that this would open China's borders to attack.
Middle reign
In 634, Emperor Taizong sent 13 high level officials, including Li Jing and Xiao Yu, to examine the circuits to see whether the local officials were capable, to find out whether the people were suffering, to comfort the poor, and to __select__ capable people to serve in civil service. (Li Jing initially recommended Wei, but Emperor Taizong declined sending Wei, stating that Wei needed to stay to point out his faults and that he could not afford to have Wei away even for a day.)
Around this time, Tang was having increasing conflicts with Tuyuhun, whose Busabo Khan Murong Fuyun, under instigation by his strategist the Prince of Tianzhu, had been repeatedly attacking Tang prefectures on the borders. At one point, Murong Fuyun sought to have a Tang princess marry his son Murong Zunwang (慕容尊王), but the marriage negotiations broke down over Emperor Taizong's insistence that Murong Zunwang come to Chang'an for the wedding. In summer 634, Emperor Taizong had the generals Duan Zhixuan and Fan Xing (樊興) lead forces against Tuyuhun, but with Tuyuhun's forces highly mobile and avoiding direct confrontation, Duan, while not defeated, could not make major gains. Once Duan withdrew, Tuyuhun resumed hostilities. In winter 634, with the Tufan king Songts?n Gampo making overtures to marry a Tang princess as well, Emperor Taizong sent the emissary Feng Dexia (馮德遐) to Tufan with an eye toward an alliance against Tuyuhun. In winter 634, he commissioned Li Jing, assisted by the other generals Hou Junji, Li Daozong, Li Daliang (李大亮), Li Daoyan (李道彥), and Gao Zengsheng (高甑生), to attack Tuyuhun. In 635, Li Jing's forces crushed Tuyuhun forces. Murong Fuyun was killed by his own subordinates, and his son Murong Shun killed the Prince of Tianzhu and surrendered. Emperor Taizong created Murong Shun the new khan, although Murong Shun was soon assassinated. Emperor Taizong then created Murong Shun's son Murong Nuohebo as the new khan.
Also in 635, Emperor Gaozu died, and Emperor Taizong, observing a mourning period, briefly had Li Chengqian serve as regent, and after he resumed his authorities less than two months later, he still authorized Li Chengqian to thereafter rule on minor matters.
In spring 636, Emperor Taizong commissioned his brothers and sons as commandants and changed their titles in accordance with the commands that they received, sending them to their posts -- with the exception of his son Li Tai the Prince of Wei, who by this point was beginning to be highly favored by him. He further allowed Li Tai to engage literary men to serve as his assistants, as Li Tai favored literature. From this point on, Li Tai would be so favored that there began to be talks that Emperor Taizong might let him displace Li Chengqian, whose favors began to wane.
In fall 636, Empress Zhangsun died. Emperor Taizong mourned her bitterly and personally wrote the text of her monument.
In summer 637, Emperor Taizong recreated the feudal scheme that he had considered and abandoned in 631, creating 35 hereditary prefect posts. (By 639, however, the system was again abandoned after much opposition.)
Sometime before 638, Emperor Taizong, disgusted with the traditional noble clans of Cui, Lu, Li, and Zheng and believing that they were abusing their highly honored names, commissioned Gao Shilian, Wei Ting, Linghu Defen (令狐德棻), and Cen Wenben to compile a work later to be known as the Records of Clans (氏族志), with the intent of dividing the clans into nine classes based on their past contributions, good deeds, and ill deeds. In an initial draft that Gao submitted, he nevertheless ranked the branch of the Cui clan that the official Cui Min'gan (崔民幹) belonged to as the highest, a decision that Emperor Taizong rebuked, as he pointed out that Gao was merely again looking at tradition and not the recent contributions. He therefore personally intervened in revising the work, reducing Cui's clan to the third class.
In fall 638, Tufan's Songts?n Gampo, displeased that Emperor Taizong had declined to give him a Tang princes in marriage and believing that Murong Nuohebo had persuaded Emperor Taizong to decline the marriage proposal, launched a major attack on Tuyuhun and then on several Tang prefectures, putting Song Prefecture (松州, roughly modern Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan) under siege. Emperor Taizong commissioned Hou, assisted by Zhishi Sili (執失思力), Niu Jinda (牛進達), and Liu Jian (劉簡), to counterattack, and Niu, who commanded the forward forces, defeated Tufan forces at Song Prefecture. Songs?n Gampo withdrew and sued for peace, but still sought to marry a Tang princess. Emperor Taizong agreed this time.
Also in 638, believing that Xueyantuo was growing increasingly strong and difficult to control, Emperor Taizong granted Yi'nan's sons Bazhuo and Jialibi (頡利苾) both lesser khan titles, to try to create dissensions between them.
In summer 639, Ashian Jiesheshuai (阿史那結社率), the younger brother of Ashina Shibobi, whom Emperor Taizong did not favor and gave little recognition to, formed a conspiracy with Ashina Shibobi's son Ashina Hexiangu (阿史那賀暹鶻) to assassinate Emperor Taizong. They had planned to wait for Li Zhi the Prince of Jin to depart from the palace in the morning and use that opportunity to attack the palace. On the day they planned, however, Li Zhi did not leave the palace, and Ashina Jiesheshuai attacked anyway but was quickly defeated, captured, and executed. After this incident, however, the officials began advocating sending the Tujue people away from the heart of the state. In fall 639, Emperor Taizong created a Tujue prince who had served him faithfully, Li Simo (李思摩, né Ashina Simo) as the khan of a newly recreated Eastern Tujue state (as Qilibi Khan), giving him all of the Tujue and Xiongnu who had surrendered as his subordinates, to be settled north of the Great Wall and the Yellow River. However, the Tujue people were fearful of Xueyantuo and initially refused to head to their new location. Emperor Taizong issued an edict to Yi'nan that he and Li Simo keep their peace and not attack each other, and after receiving from Yi'nan the assurance that he would not attack, the Tujue people advanced to the new location.
Meanwhile, Qu Wentai (麴文泰), the king of Gaochang, who had previously been submissive to Tang, had become increasingly hostile to Tang, allying with Western Tujue. In 640, Emperor Taizong commissioned Hou, assisted by Xue Wanjun, to launch a major attack on Gaochang. As they approached Gaochang, Qu Wentai died in fear and was succeeded by his son Qu Zhisheng (麴智盛). Qu Zhisheng offered to submit, but Hou demanded a surrender, which Qu Zhisheng refused. However, Hou put Gaochang under siege, and with aid from Western Tujue not arriving, Qu Zhisheng surrendered. Wei suggested that Emperor Taizong allow Qu Zhisheng to remain king, pointing out that the monetary and human costs would be high to keep a permanent garrison at Gaochang, but Emperor Taizong disagreed, and he converted Gaochang into two prefectures and annexed it into his state.
In winter 640, Songs?n Gampo sent his prime minister Ludongzan (祿東贊) as an emissary to Tang, offering tributes and again requesting marriage. Emperor Taizong created a daughter of a clansman as the Princess Wencheng, and in 641 sent Li Daozong to accompany Princess Wencheng to Tufan to preside over the wedding.
in winter 641, believing that Emperor Taizong was about to carry out sacrifices to heaven and earth at Mount Tai and would be unable to aid Eastern Tujue, Yi'nan launched a major attack on Eastern Tujue, commanded by his son Dadu (大度). Li Simo was forced to retreat inside the Great Wall. Emperor Taizong commissioned Li Shiji, assisted by Zhang Jian (張儉), Li Daliang, Zhang Shigui (張士貴), and Li Xiyu (李襲譽), to attack Xueyantuo. Li Shiji soon defeated Dadu at Nuozhen River (諾真水, flowing through modern Baotou, Inner Mongolia), and Dadu fled.
Late reign
By 642, it was clear that Li Tai had ambitions on replacing his brother Li Chengqian, and the governmental officials began to be divided into pro-Li Chengqian and pro-Li Tai factions. After urging by Wei Zheng and Chu Suiliang to take actions that would clarify that Li Chengqian's position was secure, Emperor Taizong attempted to do so by making repeated statements to that effect, but his continued favoring of Li Tai led to continued speculation among officials.
Also by 642, Xueyantuo had posed a sufficiently serious threat (albeit still formally submissive) that Emperor Taizong saw two alternatives -- destroying it by force or forming into a heqin relationship by marrying one of his daughters to Yi'nan. This particularly became an issue after the Tang general Qibi Heli (契苾何力), the chieftain of the Qibi Tribe, was kidnapped by his own subordinates and taken to Xueyantuo. In order to ransom Qibi, Emperor Taizong made a promise to eventually give his daughter Princess Xinxing to Yi'nan in marriage, and Yi'nan released Qibi.
in winter 642, an event that would eventuall precipitate wars between Tang and Goguryeo -- happened in Goguryeo. According to Chinese accounts Gao Jianwu/Go Geonmu (King Yeongnyu), the king of Goguryeo, was apprehensive about his general Yeon Gaesomun and was plotting with his other officials to kill Yeon. When Yeon received the news, he started a coup and killed the king and the high level officials. He declared King Yeongnyu's nephew Gao Zang/Go Jang (King Bojang) king, while taking power himself with the title of Mangniji (莫離支/???, regent). When Emperor Taizong received the news, there were suggestions that an attack be launched against Goguryeo, suggestions that Emperor Taizong initially declined.
In spring 643, Wei died, and Emperor Taizong mourned him bitterly, authoring Wei's monument himself and, prior to Wei's death, promising to give his daughter Princess Hengshan in marriage to Wei's son Wei Shuyu (魏叔玉). Later in spring, Emperor Taizong commissioned 24 portraits at Lingyan Pavilion to commemorate the 24 great contributors to his reign.
Also in 643, Emperor Taizong would see major turmoil among his own closest family. In spring 643, his son Li You (李祐) the Prince of Qi, angry over restrictions that his secretary general Quan Wanji (權萬紀) had often placed on him, killed Quan and declared a rebellion. Emperor Taizong sent Li Shiji against Li You, but before Li Shiji could engage Li You, Li You was captured by his own subordinate Du Xingmin (杜行敏) and delivered to Chang'an, where Emperor Taizong ordered him to commit suicide and executed 44 of his associates.
The death of Li You drew out news of another plot. Li Chengqian, who had been fearful that Emperor Taizong would eventually remove him and replace him with Li Tai, had begun to conspire with Hou Junji, Li Yuanchang (李元昌) the Prince of Han (Emperor Taizong's brother), the general Li Anyan (李安儼), and his brothers-in-law Zhao Jie (趙節) and Du He (杜荷, Du Ruhui's son) to overthrow Emperor Taizong. During the investigations in the aftermaths of Li You's rebellion, one of the co-conspirators, Li Chengqian's guard Gegan Chengji (紇干承基), was implicated by association, and in order to save himself, he revealed Li Chengqian's plot. Emperor Taizong was shocked by the news, and he appointed Zhangsun Wuji, Fang Xuanling, Xiao Yu, and Li Shiji, along with the officials in charge of the supreme court and the legislative and examination bureaus of the government to carry out a joint investigation. At the suggestion of the mid-level official Lai Ji, Emperor Taizong deposed, but did not kill, Li Chengqian, while ordering Li Yuanchang to commit suicide and executing Hou, Li Anyan, Zhao, and Du.
After Li Chenqian was deposed, Emperor Taizong briefly promised Li Tai that he would be made crown prince. However, as the investigations continued, Emperor Taizong came to the belief that Li Chengqian's downfall was driven by Li Tai's machinations, and therefore resolved to depose Li Tai as well. At Zhangsun's suggestion, Emperor Taizong created a younger son, Li Zhi the Prince of Jin (who, like Li Chengqian and Li Tai, were born of Empress Zhangsun), crown prince, who was considered kinder and gentler, while exiling Li Chengqian and Li Tai. (Starting later that year, however, Emperor Taizong began to have doubts as to whether Li Zhi's personality was sufficiently strong to serve as emperor, and he toyed with the idea of making another son, Li Ke the Prince of Wu, a son of his concubine Consort Yang (Emperor Yang of Sui's daughter), crown prince, but did not do so due to strong opposition by Zhangsun Wuji.)
Meanwhile, coming to the belief that he made an ill-advised promise to Yi'nan to give him Princess Xinxing in marriage, Emperor Taizong demanded a large amount of bride price -- 50,000 horses, 10,000 cows and camels, and 100,000 sheep -- a price that Yi'nan agreed to, but could not immediately collect and deliver. Emperor Taizong used it as an excuse to cancel the marriage agreement. Meanwhile, as as Wei Zheng had, prior to his death, recommended Hou and Li Chengqian's staff member Du Zhenglun as chancellors, Emperor Taizong came to suspect that Wei was part of the plot as well. He destroyed the monument he had authored for Wei and cancelled the betrothal between Wei Shuyu and Princess Hengshan.
In 644, with Yanqi's king Long Tuqizhi (龍突騎支), who had assisted the Tang campaign to conquer Gaochang, turning against Tang and allying with Western Tujue, Emperor Taizong sent the general Guo Xiaoke (郭孝恪), the commandant at Anxi (安西, i.e., Gaochang) to launch a surprise attack on Yanqi. Guo caught Long Tuqizhi by surprise and captured him, making his brother Long Lipozhun (龍栗婆準) regent. (The Western Tujue viceroy Ashina Quli (阿史那屈利) subsequently captured Long Lipozhun and briefly occupied Yanqi, although he then, not wanting a direct confrontation with Tang, withdrew, and the Yanqi nobles made Long Tuqizhi's cousin Long Xuepoanazhi (龍薛婆阿那支) king.)
Also in 644, with Goguryeo attacking Silla and Silla requesting aid, Emperor Taizong decided to prepare for a campaign to conquer Goguryeo. He arrested the emissaries that Yeon sent to the Tang court, accusing them of disloyalty to King Yeongnyu. By winter 644, the mobilization was in full force. (Apparently because of Tang's preparation to attack Goguryeo, however, the reconstituted Eastern Tujue people, fearing an attack from Xueyantuo at a time that Tang would be ill-equipped to assist, panicked and abandoned their khan Li Simo, fleeing into Tang territory. Emperor Taizong reabsorbed the Eastern Tujue people into Tang, while making Li Simo a general in his army.)
In spring 645, Emperor Taizong departed from Luoyang and led the troops northeast, behind forward forces commanded by Li Shiji and Li Daozong. By summer 645, Tang forces had captured Liaodong (遼東, in modern Liaoyang, Liaoning), and headed southeast toward the Goguryeo capital Pyongyang. Emperor Taizong defeated a large force commanded by the Gogureyo generals Gao Yanshou (高延壽) and Gao Huizhen (高惠真) and then put Anshi (安市, in modern Anshan, Liaoning) under siege. However, the capable defense put up by Anshi's commanding general (whose name is not recorded in history but traditionally is believed to be Yang Manchun) stymied Tang forces and, in late fall, with winter fast approaching and his food supplies running out, Emperor Taizong withdrew. He much regretted launching the campaign and made the comment, "If Wei Zheng were still alive, he would never have let me launch this campaign." He reerected the monument he authored for Wei and summoned Wei's wife and children to meet him, treating them well. He also began to suffer from an illness or injury -- which might have been inflicted during the Gogureyo campaign -- an ilnness that he would never appear to completely recover from.
Meanwhile, in the aftermaths of the Goguryeo campaign, Xueyantuo's Duomi Khan Bazhuo (拔灼, son of Yi'nan, who had died earlier in 645) launched attacks against Tang's border prefectures, with largely inconclusive results. In spring 646, the Tang generals Qiao Shiwang (喬師望) and Zhishi Sili counterattacked, defeating Bazhuo's forces, causing him to flee. His vassals Huige, Pugu (僕骨), and Tongluo (同羅) tribes took the opportunity to rebel and attack him. Hearing this, Emperor Taizong launched a major attack, commanded by Li Daozong, Ashina She'er (阿史那社爾), Zhishi, Qibi, Xue Wanche, and Zhang Jian, against Xueyantuo. With Xueyantuo under attack from multiple sides, Bazhuo was killed by Huige forces, and the remaining Xueyantuo people fled and supported Bazhuo's cousin Duomozhi (咄摩支) as Yitewushi Khan, but soon offered to submit to Tang. Emperor Taizong sent Li Shiji toward Duomozhi's location, with the direction to either accept his submission or destroy him. Duomozhi surrendered and was taken to Chang'an, ending Xueyantuo's rule over the region. The other tribes formerly submissive to Xueyantuo offered Emperor Taizong the title of "Heavenly Khan" and thereafter largely became submissive to Tang. Tang nominally established seven command posts and six prefectures over the region. (Huige's khan Yaoluoge Tumidu (藥羅葛吐迷度), while submissive to Tang, for some time tried to take control over the region himself, but was subsequently assassinated in 648, and there would be no other organized attempt by Huige to take over the region until for about another century.)
After the victory over Xueyantuo, Emperor Taizong again turned his attention toward to Goguryeo, cutting off relations once more and considering another campaign. Under suggestions by some of his officials, he decided to launch harassment campaigns against Goguryeo's northern region on a yearly basis, to weaken Goguryeo gradually. The first of these campaigns was launched in spring 647, with Niu Jinda and Li Shiji in command, and would reoccur.
In 648, Emperor Taizong launched another campaign, commanded by Ashina She'er, aimed at Qiuzi (龜玆, in modern Akesu Prefecture, Xinjiang]), but first attacking Yanqi and killing Long Xuepoanazhi and replacing him with his cousin Long Xiannazhun (龍先那準). Ashina She'er advanced on Qiuzi and captured its king Bai Helibushibi (白訶黎布失畢), making his brother king instead.
By summer of 649, Emperor Taizong was seriously ill -- with some believing that his illness was caused by his taking pills given him by alchemists. Believing Li Shiji to be capable but fearing that he would not be submissive to Li Zhi, he demoted Li Shiji out of the capital to be the commandant at remote Die Prefecture (疊州, roughly modern Gannan Tibetan Autonomous Prefecture, Gansu), with instructions to Li Zhi that if if Li Shiji hesitated, to execute him immediately, and if he did not, to recall him after Emperor Taizong's death and make him chancellor. Li Shiji, when receiving the order and realizing that his life was at stake, immediately departed for Die Prefecture. (After Emperor Taizong's death, Li Zhi would indeed recall Li Shiji and make him chancellor.) Soon thereafter, Emperor Taizong, after entrusting Li Zhi to Zhangsun Wuji and Chu, died at his summer palace Cuiwei Palace (翠微宮). His death was initially kept a secret, and three days later, after his casket had been returned to Chang'an, his death was announced, and Li Zhi took the throne as Emperor Gaozong.
Taizong "reign" 616-649 Colors show the succession of Taizong (Tang) conquest in Asia: Shanxi (617: his father is governor, Taizong encouraged him to revolt.) Sui's Empire Protector (618). Tang dynasty 618. Controlled all of Sui's China by 622-626. Submit the Oriental Turks territories (630-682) Tibetan's King recognizes China as their emperor (641-670) Submit the Occidental Turks territories (642-665) (idem) add the Oasis (640-648: northern Oasis; 648: southern Oasis) [Not shown in the map: Conquest of Korea by his son (661-668)] The two darkest area are truly the Chinese empire, the 3 lightest area are temporaly vasalised. Borders are not factual, they are indicatives.
Taizong "reign" 616-649
Colors show the succession of Taizong (Tang) conquest in Asia:
Shanxi (617: his father is governor, Taizong encouraged him to revolt.) Sui's Empire Protector (618). Tang dynasty 618. Controlled all of Sui's China by 622-626. Submit the Oriental Turks territories (630-682) Tibetan's King recognizes China as their emperor (641-670) Submit the Occidental Turks territories (642-665) (idem) add the Oasis (640-648: northern Oasis; 648: southern Oasis) [Not shown in the map: Conquest of Korea by his son (661-668)] The two darkest area are truly the Chinese empire, the 3 lightest area are temporaly vasalised. Borders are not factual, they are indicatives.
The Sui dynasty tried to invade Goguryeo in 598, 612, 613 & 614. Taizong campaign was in 645. Gaozong's campaigns were in 661, 667 & 668. (Map: end of the 5th)
The Sui dynasty tried to invade Goguryeo in 598, 612, 613 & 614. Taizong campaign was in 645. Gaozong's campaigns were in 661, 667 & 668. (Map: end of the 5th)
Era name
* Zhen'guan (貞觀 zhēn guān) 627-649
Chancellors during reign
* Xiao Yu (626, 627, 630, 643-646)
* Chen Shuda (626)
* Feng Deyi (626-627)
* Yuwen Shiji (626-627)
* Gao Shilian (626-627, 638-647)
* Fang Xuanling (626-643, 643-648)
* Zhangsun Wuji (627-628, 645-649)
* Du Yan (627-628)
* Du Ruhui (628-629)
* Li Jing (628-634)
* Wang Gui (628-633)
* Wei Zheng (629-642)
* Wen Yanbo (630-637)
* Dai Zhou (630-633)
* Hou Junji (630-632, 632-643)
* Yang Shidao (636-643, 645)
* Liu Ji (639-645)
* Cen Wenben (642-645)
* Li Shiji (643-649)
* Zhang Liang (643-646)
* Ma Zhou (644-648)
* Chu Suiliang (644-647, 648-649)
* Xu Jingzong (645)
* Gao Jifu (645)
* Zhang Xingcheng (645)
* Cui Renshi (648)
Family
* Father
o Emperor Gaozu of Tang
* Mother
o Duchess Dou, Emperor Gaozu's wife, daughter of Dou Yi (竇毅) the Duke of Shenwu during Northern Zhou and Sui Dynasty and the Princess Xiangyang daughter of Yuwen Tai, posthumously honored as Empress Taimushunsheng
* Wife
o Empress Zhangsun (created 626, d. 636), mother of Crown Princes Chengqian and Zhi, Prince Tai, and Princesses Changle, Jinyang, and Xincheng
* Major Concubines
o Consort Xu Hui (徐惠) (627-650), titled Chongrong (充容), posthumously honored Xianfei (賢妃)
o Consort Yang, daughter of Emperor Yang of Sui, mother of Princes Ke and Yin
o Consort Yin, mother of Prince You
o Consort Wang, mother of Prince Yun
o Consort Yan, mother of Princes Zhen and Xiao
o Consort Wei, mother of Prince Shen and Princess Linchuan
o Consort Yang, mother of Prince Fu
o Consort Yang, formerly wife and princess of Li Yuanji the Prince of Qi, mother of Prince Ming
o Consort Wu, later wife and empress of Emperor Gaozong, later Emperor of Zhou, commonly known as Wu Zetian
* Sons
o Li Chengqian (李承乾), initially the Prince of Changshan (created 620), later the Prince of Zhongshan (created 622), later the Crown Prince (created 626), later reduced to commoner rank (deposed 643), posthumously honored as Prince Min of Changshan
o Li Kuan (李寬) (d. 620?), posthumously created the Prince of Chu
o Li Ke (李恪), initially the Prince of Changsha (created 620), later the Prince of Han, later the Prince of Shu (created 628), later the Prince of Wu (created 636, forced to commit suicide 653), posthumously created the Prince of Yulin
o Li Tai (李泰), initially the Prince of Yidu (created 620), later the Prince of Wei (created 621), later the Prince of Yue (created 628), later the Prince of Wei (created 636), later demoted to the Prince of Donglai (demoted 643), later the Prince of Shunyang (created 643), later Prince Gong of Pu (created 647)
o Li You (李祐), initially the Prince of Yiyang (created 625), later the Prince of Chu, later the Prince of Yan (created 628), later the Prince of Qi (created 636, forced to commit suicide 653)
o Li Yin (李愔), initially the Prince of Liang (created 631), later the Prince of Shu (created 636), later reduced to commoner rank (deposed 653), later the Prince of Peiling (d. 667), posthumously created Prince Dao of Shu
o Li Yun (李惲), initially the Prince of Tan (created 631), later the Prince of Jiang (created 636, committed suicide 674)
o Li Zhen (李貞), initially the Prince of Han (created 631), later the Prince of Yue (created 636, committed suicide 688)
o Li Zhi (李治), initially the Prince of Jin (created 631), later the Crown Prince (created 643), later Emperor Gaozong of Tang
o Li Shen (李慎), initially the Prince of Shen (created 631), later the Prince of Ji (created 636), later reduced to commoner rank (deposed and d. 688)
o Li Xiao (李囂), Prince Shang of Jiang (created 631, d. 632)
o Li Jian (李簡), the Prince of Dai (created and d. 631)
o Li Fu (李福), the Prince of Zhao (created 639, d. 670)
o Li Ming (李明), initially the Prince of Chao (created 647), later demoted to Prince of Lingling (demoted 680 or 681, forced to commit suicide 682)
* Daughters
o Princess Xiangcheng (d. 651)
o Princess Runan
o Princess Nanping
o Princess Sui'an
o Princess Changle
o Princess Yuzhang
o Princess Baling (forced to commit suicide 653), posthumously created the Princess Bijing
o Princess Pu'an
o Princess Dongyang
o Princess Linchuan (d. 682)
o Li Jing (李敬), the Princess Qinghe (d. 664)
o Li Shu (李淑), the Princess Lanling
o Princess Jin'an
o Princess Ankang
o Princess Xingxing
o Princess Chengyang
o Princess Gaoyang (forced to commit suicide 653), posthumously created the princess Hepu
o Princess Jinshan
o Li Mingda (李明達), the Princess Jinyang
o Princess Changshan (d. 656)
o Princess Xincheng
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