| 網筆號： | 文武大聖大廣孝皇帝 | |||||||||||||
| 廟號： | 太宗 | |||||||||||||
| 陵墓： | 昭陵 | |||||||||||||
閱讀李世民 Li Shimin在百家争鸣的作品!!! 閱讀李世民 Li Shimin在诗海的作品!!! | ||||||||||||||
生卒時間：隋文帝開皇十八年十二月二十二日（公元599年）——唐太宗貞觀二十三年（649年）五月二十六日（50歲）
廟號:太宗
謚號：文皇帝（唐高宗加謚文武聖皇帝；唐玄宗加謚文武大聖皇帝、文武大聖大廣孝皇帝）
歷史地位：民族英雄、天可汗、千古一帝
【唐太宗早年】
唐太宗於隋開皇十八年十二月二十二日（公元599年）出生於武功別館，是唐高祖李淵與竇皇后的次子。公元614年娶妻長孫氏，武德九年八月二十一日立為皇后，即長孫皇后。
隋大業十一年（615年），隋煬帝被突厥十萬騎圍困於雁門（今山西代縣），李世民應募從屯衛將軍雲定興前往救援，提出虛張軍容，晝引旌旗數十裏，夜以鉦鼓相應的疑兵計。時值東都及諸郡援兵亦至忻口（今忻縣北），迫使突厥始畢可汗解圍而去。十三年六月，與其兄李建成率兵攻西河（今汾陽），首戰獲勝，促使李淵决意西嚮關中。任右領軍大都督，統右三軍，封敦煌郡公。七月隨李淵自太原（今太原西南）南下。途中李淵一度動搖，欲還師更圖後舉。世民堅决主張繼續進軍，提出先入鹹陽，號令天下的方略。八月，進攻霍邑（今霍州），先率輕騎至城下，誘隋守將宋老生出戰，繼而率騎猛衝其側背，配合李淵、建成正面攻擊，斬宋老生，剋其城。九月，軍至河東（今永濟西南），力主急速進軍長安（今西安），遂奉命率前軍西渡黃河，順利占領渭河以北地區，各大族豪強紛至軍門投效，數支農民起義軍亦來歸附，兵力迅速發展至13萬人。十一月，會諸軍攻剋長安。李淵立代王楊侑為帝，即隋恭帝，改大業十三年為義寧元年。以光祿大夫、大將軍、太尉唐公為假黃鉞、使持節、大都督內外諸軍事、尚書令、大丞相，進封唐王，李世民為京兆尹，改封秦公，義寧二年三月，為右元帥，徙封趙國公。
同年（618年）五月，隋恭帝禪位於唐，唐王即皇帝位，國號大唐，改元武德。武德元年，以趙公世民為尚書令、右翊衛大將軍，進封秦王。
唐朝建立以後，為統一全國，先後進行了六次大的戰役。這六個戰役李世民就指揮了四個，全部取得了勝利，為唐王朝立下了赫赫戰功。
第一次是對隴右薛舉父子集團的戰役，唐武德元年，薛舉率軍進攻關中，雙方在現陝西長武縣發生激戰，在這裏，李世民打了他一生中唯一的一次大敗仗，退回長安。但不久，他便在淺水原之戰徹底打敗薛軍，消滅了隴東集團。
第二次，劉武周依附突厥，南下進攻唐朝，攻占了晉陽，李世民不畏艱險，終於擊潰了敵人主力，並乘勝追擊，兩天不吃飯，三天不解甲，徹底消滅了敵軍，收復了丟失的土地。
第三次是對王世充和竇建德的戰役。這次戰役規模為唐統一戰爭中最大的。在這次戰役中，李世民先將王世充擊敗，圍困在洛陽，令其無糧草供應，待其自斃。就在洛陽將下未下之時，河北的竇建德軍十餘萬衆號稱三十萬為救援王世充，突然出現在唐軍背後，李世民力排衆議，在虎牢之戰中大敗竇建德軍，生擒竇建德。洛陽的王世充也衹得投降，這次李世民一舉兩剋，取得了决定性的勝利。
第四次是平定劉黑闥的戰役，劉黑闥是竇建德的部下，他打着為竇建德復仇的旗號，在河北起兵反唐。李世民指揮了平定其第一次起兵的戰役，僅僅兩個月就取得了勝利。（其他兩個戰役是由李孝恭指揮的平定杜伏威的江淮軍和平定以江陵為根據地的蕭銑的梁政權）。
李世民自此威望日隆，尤其是在虎牢之戰後進入長安時，受到部分軍民以皇帝的禮儀招待。武德四年鼕十月，封為天策上將、領司徒、陜東道大行臺尚書令，食邑增至二萬戶。高祖又下詔特許天策府自置官屬，儼然形成一個小政府機構。
李世民在戰鬥中註重戰前偵察，雖屢次遇險，但每次戰鬥都能作到知己知彼，善於製造戰機，當敵強我弱時，他經常用“堅壁挫銳”的戰法拖垮敵人，戰鬥中身先士卒，親自率領騎兵突擊敵陣，勝利後勇追窮寇，不給敵人喘息之機，因此獲得了每次戰役的勝利。在統一邊疆的戰爭中，他運籌帷幄，决勝千裏，明於知將，選拔良纔，取得了戰爭的勝利。李世民用他卓越的軍事才能，為大唐帝國的建立和發展做出了巨大的貢獻，他不愧為我國歷史上傑出的軍事傢，他的赫赫武功也永垂青史！
【玄武門之變】
玄武門之變發生於唐高祖武德九年（626年）。617年，李淵在李世民支持下在太原起兵反隋並很快占領長安。618年，隋煬帝被宇文化及縊殺之後，李淵建立唐朝，並立世子李建成為太子。據說太原起兵是李世民的謀略，李淵曾答應他事成之後立他為太子。但天下平定後，李世民功名日盛，李淵卻猶豫不决。李建成隨即聯合四弟齊王李元吉，排擠李世民。李淵的優柔寡斷，也使朝中政令相互衝突，加速了諸子的兵戎相見。是年，李建成嚮李淵建議由李元吉做統帥出徵突厥，藉此要把握住秦王的兵馬，以防止李世民篡奪皇太子之位。李世民在危急時刻决定背水一戰，先發製人。搶先一步殺死大哥李建成和四弟李元吉，這就是歷史上有名的玄武門之變。玄武門事變之後僅僅三天李世民便被立為皇太子，從他父親手裏接過政府的實際控製權。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。
【史學評價】
《新唐書》：
甚矣，至治之君不世出也！禹有天下，傳十有六王，而少康有中興之業。湯有天下，傳二十八王，而其甚盛者，號稱三宗。武王有天下，傳三十六王，而成、康之治與宣之功，其餘無所稱焉。雖《詩》《書》所載，時有闕略，然三代千有七百餘年，傳七十餘君，其卓然著見於後世者，此六七君而已。嗚呼，可謂難得也！
《舊唐書》評價：
史臣曰：臣觀文皇帝發跡多奇，聰明神武。拔人物則不私於黨，負志業則鹹盡其纔。所以屈突、尉遲，由仇敵而願傾心膂；馬周、劉洎，自疏遠而卒委鈞衡。終平泰階，諒由斯道。嘗試論之：礎潤雲興，蟲鳴螽躍。雖堯、舜之聖，不能用檮杌、窮奇而治平；伊、呂之賢，不能為夏桀、殷辛而昌盛。君臣之際，遭遇斯難，以至抉目剖心，蟲流筋擢，良由遭值之異也。以房、魏之智，不逾於丘、軻，遂能尊主庇民者，遭時也。況周發、周成之世襲，我有遺妍；較漢文、漢武之恢弘，彼多慚德。跡其聽斷不惑，從善如流，千載可稱，一人而已！
吳兢在《貞觀政要·序》中說：“太宗時政化，良足可觀，振古而來，未之有也。”
《貞觀政要》集論的撰者元朝的戈直說：“夫太宗之於正心修身之道，齊傢明倫之方，誠有愧於二帝三王之事矣。然其屈己而納諫，任賢而使能，恭儉而節用，寬厚而愛民，亦三代而下，絶無而僅有者也。後之人君，擇其善者而從之，其不善者而改之，豈不交有所益乎！”這裏所說，太宗在正心修身，齊傢明倫方面，有愧於二帝三王之事，主要是指太宗與其兄李建成的皇位之爭。
明憲宗在命儒臣訂正重刊《貞觀政要》時寫道：“太宗在唐為一代英明之君，其濟世康民，偉有成烈，卓乎不可及已。所可惜者，正心修身，有愧於二帝三王之道，而治未純也。”
【豐功偉績】
1. 他不拘一格的用人，對人材的使用及領導達到了極高的境遇；
2 .他獨具慧眼，看到了個人力量的不足，充分認識到君王如石、良臣如匠，方有美玉問世，對大臣的各項進步之言豁達地予以采納；
3 .不獨斷專行、初步確立了三權分立、互相監督的政治管理制度，規定法令甚至包括自己（影響國傢政策的那一部分）旨意需門下省審查副署後方可生效發佈，保證了政策的可行性、及時發現並糾正。杜絶了不良政策對國傢及人民的違害與影響；
4 .認識到人命至重、不可妄殺的法政政策，規定死刑需三復奏（外地五復奏）復審批準後方可行刑，這就不難認人們想起貞觀四年（630年）全國判死刑纔29人、貞觀六年（632年）全國死刑犯390人，太宗審查時令全部390人回傢團年、待來年秋收後回來復刑，結果390人均準時到來、無一人逃亡。
5 .太宗朝武功之盛，除對高句麗戰爭上沒有取得戰略勝利外都取得了輝煌的勝利（東突厥、吐𠔌渾、高昌、安西四鎮、漠北薛延陀等），這與當時的國力、軍隊戰鬥力、整體戰略、用人選將與配合默契、過程協調一致等重要因素是分不開的，因此在中華歷史上的名將名相中，貞觀朝占有相當的比例，在中華軍事史上，貞觀朝的戰例也多被引用；
6 . 氣吞天下的“天可汗”氣質，李世民多次以少嚇多，經典之役就是在渭水單騎嚇退突厥10萬精騎，就對比宋真宗在寇準一再堅持和請求下纔勉強在大軍護衛下到達澶州南城，而又要戰戰兢兢的馬上要回去是何等的天壤之別啊！
7 .胸懷大局、四海一統的民族和外交政策，太宗朝的民族和外交政策取得了輝煌的勝利，四海之內衹要知道中國的均努力內附，以唐為榮，樂不思蜀，他們不但同唐人一樣可以自由自在的生存，還可以做官，著名的少數民族將領阿史那思摩、執思失力、契芯何力、黑齒常之、乃至後世的高仙芝、李光弼等都為唐朝做出了傑出貢獻，在他們身上正好反映出李世民民族政策的光輝，現在的唐人、唐人街也正時那時繁榮富強、威甲四海、文禮之邦的生動寫照；
8 .完善科舉制度、大力興辦學校、重視教育活動、普及官吏選聘、當時的國子學、太學之盛、地方也有不少學校，如此纔不難想起當時的教化呢，同時當時的科舉也規範化、考選公平，以進士科最為傑出，如此纔有太宗見新科進士魚貫而出，喜言“天下英雄、入朕彀夷”，唐朝的教育及科舉為政治上提供優秀人才同文化精髓——唐詩及經濟發展做出傑出貢獻；
9 .工書法、富文詞，太宗皇帝個人修養及天賦極高，在書法同文詞上也頗有名氣，在他大力宏揚和鼓勵支持下，纔有唐代書法、文學、藝術之盛；
10 .倡導廉政、節儉、樸素、重視農田水利，太宗朝在廉政建設方面是相當成功的，他並沒有像朱元璋一樣嚴懲貪官污吏，而是建立一個廉潔奉公、遵紀守法的中央領導班子、重視地方長官選舉，當時朝廷中不少卿相傢境貧睏，溫彥博、戴胄、於志寧、魏徵、張玄素等等，再加上良好風氣的宣傳和行政監督，及時預防了官員犯錯，因此當時的官員相當奉公守法、廉潔自律；太宗皇帝也比較註意節儉，不濫用民力、註意與民休息，當時社會形成了一種樸素求實的作風；太宗皇帝也相當重視農業，京官外巡回京太宗先問及此事，因太子冠禮與農時違背而更改；
11 . 由於社會安定，商業經濟得到發展，全國新興了許多商業城市，城市業有相當的發展，廣州、杭州、揚州、成都、江陵、涼州等城市經濟發展相當迅猛，長安同洛陽作為世界經濟大都會就不言而喻了，這為封建經濟登頂奠定了堅實的基礎；
12 .對玄奘佛學的支持同西遊的肯定，打通並維護河西走廊－絲綢之路及東聯新羅、日本，促進了中西文化交流與經濟發展，文成公主下嫁吐蕃，使吐蕃從奴隸製社會邁入封建社會，開發並促進了西藏的發展；
綜上所述，唐太宗李世民不愧為我國歷史上一位偉大的政治傢、書法傢、卓越的領袖、影響中華乃至世界進程的傑出人物，他為中華民族同人民做出了傑出貢獻，留下了輝耀千古的豐功偉業及精神財富，因此受到人們的崇敬；築東陽先生所說“他是繼孔子之後中國數一數二的偉人”。
【貞觀之治】
貞觀之治
形成原因
第一、隋朝政治制度和經濟繁榮為唐朝加強中央集權和發展經濟創造了條件；而隋煬帝暴政、奢侈腐化、奴役百姓、窮兵黷武，破壞社會生産，激化社會矛盾，導致農民起義。唐初統治者親眼看到了農民戰爭瓦解隋朝的過程，認識到了廣大農民對封建統治穩定的重要性，吸取隋亡教訓，調整統治政策，以緩和階級矛盾，穩定社會秩序，恢復經濟。
第二、因為上述因素，唐太宗確定了“安百姓”、“重人才”、“強政治”的治國思想，並通過一係列的制度政策、措施和不懈的實踐去實現。首先，唐太宗認識到了統治者與人民是“舟與水”的關係，通過土地賦稅制度的調整以“安百姓”。二是認識到了重用人才，虛懷納諫的意義，得人善任，從諫如流，營造出政治清明的氛圍，保證了較為開明正確的政治、經濟、民族、外交、文化上的政策得以製定和實施。三是加強政治，完善三省六部製和科舉製，以鞏固中央集權，提高行政效率，擴大統治基礎。
註意：用人和納諫，既是貞觀之治出現的原因，又是貞觀之治的重要表現。
在李世民統治其間，唐朝國力強盛，被稱為貞觀之治。晚年著《帝範》一書以教戒太子，其中總結了他一生的政治經驗，也對自己的功過進行了評述。
他在位期間，推行府兵製、租庸調製和均田製，並積極推行科舉製。
630年，擊敗東突厥，被突厥各部尊為“天可汗”。641年嫁文成公主給吐蕃的鬆贊幹布。
649年，命太子李治到金液門代理國事。李世民於649年7月駕崩於長安含風殿，享年52歲，葬於今陝西禮泉東北50多裏的山峰上的昭陵。謚號為“文皇帝”。
唐太宗善於聽從大臣的批評和見解，魏徵直諫200多次直陳他的過失。
唐太宗還精擅書法，以行書寫碑，為後世鼻祖。著名作品有《溫泉銘》《晉祠銘》等。死後更以東晉書法大傢王羲之所作《蘭亭集序》為陪葬品。
貞觀之治是指唐朝初期出現的太平盛世。由於唐太宗能任人為賢，知人善用；開言路，虛心納諫，重用魏徵等；並采取了一些以農為本，減輕徭賦，休養生息，厲行節約，完善科舉製等政策，使得社會出現了安寧的局面。與後來李隆基的“開元盛世”並肩而立。
唐太宗李世民在位23年，使唐朝經濟發展，社會安定，政治清明，人民富裕安康，出現了空前的繁榮。由於他在位時年號為貞觀，所以人們把他統治的這一段時期稱為“貞觀之治”。“貞觀之治”是我國歷史上最為璀璨奪目的時期。
太宗吸取隋朝滅亡的原因，非常重視老百姓的生活。他強調以民為本，常說：“民，水也；君，舟也。水能載舟，亦能覆舟。”太宗即位之初，下令輕徭薄賦，讓老百姓休養生息。唐太宗愛惜民力，從不輕易徵發徭役。他患有氣疾，不適合居住在潮濕的舊宮殿，但他一直在隋朝的舊宮殿裏住了很久。
貞觀之初，在唐太宗的帶領下，君臣和諧，全國上下一心，經濟很快得到了好轉。到了貞觀八九年，牛馬遍野，百姓豐衣足食，夜不閉戶，道不拾遺，出現了一片欣欣嚮榮的升平景象。
太宗在位20多年，進諫的官員不下30餘人，其中大臣魏徵一人所諫前後200餘事，數十萬言，皆切中時弊，對改進朝政很有幫助。
太宗十分註重人才的選拔，嚴格遵循德纔兼備的原則。太宗認為衹有選用大批具有真纔實學的人，才能達到天下大治，因此他求賢若渴，曾先後５次頒布求賢詔令，並增加科舉考試的科目，擴大應試的範圍和人數，以便使更多的人才顯露出來。由於唐太宗重視人才，貞觀年間涌現出了大量的優秀人才，可謂是“人才濟濟，文武兼備”。正是這些棟梁之才，用他們的聰明才智，為“貞觀之治”的形成做出了巨大的貢獻。
唐太宗十分註重法治，他曾說：“國傢法律不是帝王一傢之法，是天下都要共同遵守的法律，因此一切都要以法為準。”法律製定出來後，唐太宗以身作則，帶頭守法，維護法律的劃一和穩定。在貞觀時期，真正地做到了王子犯法與民同罪。執法時鐵面無私，但量刑時太宗又反復思考，慎之又慎。他說：“人死了不能再活，執法務必寬大簡約。”由於太宗的苦心經營，貞觀年間法製情況很好，犯法的人少了，被判死刑的更少。據載貞觀三年，全國判死刑的纔29人，幾乎達到了封建社會法製的最高標準——“刑措”即可以不用刑罰。
以民為本的思想，廣開言路，虛懷納諫的胸襟；重用人才，唯才是任的準則；鐵面無私，依法辦事的氣度；構成了貞觀之治的基本特色，成為封建治世最好的榜樣。使唐朝在當時與西方國傢相比，無論在政治、經濟，還是文化上都走在世界的最前列。
一、社會秩序空前安定
史書記載：
貞觀年間“官吏多自清謹。製馭王公、妃主之傢，大姓豪猾之伍，皆畏威屏跡，無敢侵欺細人。商旅野次，無復盜賊，囹圄常空，馬牛布野，外戶不閉。又頻緻豐稔，米鬥三四錢，行旅自京
[《貞觀長歌》中的李世民(唐國強飾)]
《貞觀長歌》中的李世民(唐國強飾)
師至於嶺表，自山東至於滄海，皆不糧，取給於路。入山東村落，行客經過者，必厚加供待，或發時有贈遺。此皆古昔未有也”。
二、開放國境
由於東羅馬帝國（395—1453）的衰落，西方變得支離破碎。到了隋朝時中國已經幾欲是世界上最強大的國傢了，而唐帝國尤其是貞觀時期的唐朝更是當時世界唯一的文明最為強盛的大一統帝國，首都長安是世界性的大都會，各地民商來往不斷，就象今天的美國紐約一樣。那時的唐帝國是世界各國仁人志士心目中的“陽光地帶”，各國的傑纔俊士冒着生命危險也要往唐帝國跑。來自世界各國的外交使節紛紛贊嘆唐朝的盛世，唐朝高度發展的文化，使來到唐朝的各國人，大多數以成為大唐人為榮。不僅首都長安，全國各地都有來自國外的“僑民”在當地定居，尤其是新興的商業城市，僅廣州一城的西洋僑民就有二十萬人以上。貞觀時期的唐王朝王朝是中國歷史上少有的完全開放的王朝，比漢朝的僅限於貿易和傳教還要開放，以至於各國各地的普通老百姓都可以來到唐朝一睹唐帝國的的風采，唐朝政府還在設立流所（和現在的使館差不多），頗為開放邊境和關口。極盡吸收外來文化和物質文明。
唐帝國除了接受大批的外國移民外，還接收一批又一批的外國留學生來中國學習先進文化，僅日本的官派的公費留學生就接收了七批，每批都有幾百人。民間自費留學生則遠遠超過此數。這些日本留學生學成歸國後，在日本進行了第一次現代化運動 ――“大化改新”，也就是中國化運動，上至典章制度，下至服飾風俗，全部仿效當時的貞觀王朝，使處於原始部落狀態的日本民族平空躍進了一千年。
日本民族並不高明，它衹是善於學習而已。這個步子比別人慢半拍的民族有一個最大的優點――落後但不固執。當外來文明入侵時，它總是虛懷若𠔌地主動接受比本民族先進的文化，用最快最便捷的方式接受人類文明的先進成果，使自己快速躍進到先進民族的行列。
一個民族落後並不可怕，固執纔是最可怕的！
三、政治清平
中國官場的貪污病菌是無孔不入的，以至占絶大多數的國人都認定貪污是人類社會的不治之癥，衹要是有“官”的地方就避免不了貪污。當從英美等國歸來的留學生嚮他們的親朋好友陳述這些國傢基本上消滅了貪污時，沒有幾個人不認為他是在鬍說八道。其實，貪污並不是人類社會的普遍現象，地球上就有不少文明程度較高的國傢基本上消滅了貪污。不僅是美利堅和英吉利等現代化強國，就連主要由華人組成的新加坡也基本上消滅了貪污。
這裏所說的基本上消滅了貪污並不是說完全杜絶了貪污現象，而是指貪污行為在整個官場中屬極個別的現象，且貪污的數額不大（一年的貪污額一般不會超過此人一年的薪水），持續的時間也不會很長（連續作案三年以上的少之又少），都會很快敗露且受到毫不留情的嚴懲。
貞觀時期是中國歷史上基本沒有貪污的政治，這也許是李世民最值得稱導的政績。在李世民統治下的中國，皇帝率先垂範，官員一心為公，吏佐各安本份，濫用職權和貪污瀆職的現象降到了歷史上的最低點。尢為可貴的是：李世民並沒有用殘酷的刑罰來檠告貪污，主要是以身示範和製定一套盡可能科學的政治體製來預防貪污。在一個精明自律的統治者面前，官吏貪污的動機很小，貪官污吏也不容易找到藏身之地。防範貪污主要取决於一套科學修明的政治體製，光靠事後的打擊衹能取效於一時，不能從根子上鏟除貪污賴以滋生的社會土壤。
四、分權制度
中國封建體製的主要特徵是權力高度集中，地方服從中央，中央又唯皇帝馬首是瞻。這種中央集權的政治體製極大地限製了國民的創造性、主動性和靈活性，且極易釀成暴政。
中國封建社會的中央政府組織實行“三省六部製”，但貞觀王朝的三省職權劃分則初步體現了現代化政治特徵――分權原則。中書省發佈命令，門下省審查命令，尚書省執行命令。一個政令的形成，先由諸宰相在設於中書省的政事堂舉行會議，形成决議後報皇帝批準，再由中書省以皇帝名義發佈詔書。詔書發佈之前，必須送門下省審查，門下省認為不合適的，可以拒絶“副署”。詔書缺少副署，依法即不能頒布。衹有門下省“副署”後的詔書纔成為國傢正式法令，交由尚書省執行。這種政治運作方式很有點類似現代民主國傢的“三權分立” 製，西方在十七世紀興起的分權學說，李世民早在一千多年前就已運用於中國的政治體製，進一步說明了貞觀王朝的文明程度是何等之高。最為難能可貴的是，李世民規定自己的詔書也必須由門下省“副署”後才能生效，從而有效地防止了他在心血來潮和心情不好時作出有損他清譽的不慎重决定。中國歷史上出了八百五十三個帝王，衹有李世民一人擁有如此傑出智慧和胸襟（美國的開國總統華盛頓有點像他的學生）。
五、商業發達
中國封建王朝歷來的經濟特徵是“重農抑商”，商業在國民經濟中所占的比重相當低，商人的地位也因之比種田人要低好幾個等次。這也是中國的封建經濟一直得不到實質性發展的主要原因。
貞觀王朝是中國歷史上少有的不歧視商業的封建王朝，不但不歧視，還給商業發展提供了許多便利條件，這進一步地體現了李世民將眼光放到很遠。在李世民政府的倡導下，貞觀王朝的商業經濟有了迅速和長足地進展，新興的商業城市象雨後春筍般地興起。當時世界出名的商業城市，有一半以上集中在中國。除了沿海的交州、廣州、明州、福州外，還有內陸的洪州（江西南昌）、揚州、益州（成都）和西北的沙州、涼州。首都長安和陪都洛陽則是世界性的大都會。
自漢開闢的“絲綢之路” 一直是聯繫東西方物質文明的紐帶，唐朝疆域遼闊，在西域設立了安西四鎮，西部邊界直達中亞的石國（今屬哈薩剋斯坦），為東西方來往的商旅提供了安定的社會秩序和有效的安全保障，結果絲稠之路上的商旅不絶於途，品種繁多的大宗貨物在東西方世界往來傳遞，使絲稠之路成了整個世界的黃金走廊。
“貞觀之治”總結
1 含義：在唐太宗統治時期，社會秩序比較安定，階級矛盾相對緩和，經濟繁榮，國力強盛。唐太宗的年號叫“貞觀”，歷史上把這一時期比較清明的封建統治稱為“貞觀之治”。
2 原因：1。隋唐更替，其間的戰爭是人口減少約2000萬以上，戰爭結束，人少地多，人心思安，這是貞觀之治産生的最重要原因。
2。隋開創了大運河以及科舉，大運河的勞民導致隋滅亡，但這些卻促成了貞觀之治的産生。開創大運河，弊在當時，功在千秋。
3。前期的李世民汲取隋失敗的教訓，正如漢朝初期汲取秦滅亡的教訓一樣，讓百姓休養生息，李世民自己也基本能虛懷從諫。但是，晚期的李世民變了，不再那麽虛懷從諫，不在讓百姓休養生息，而是好大喜功，徵服高麗失敗。這些是貞觀之治不能持久的原因。
3 政績：
第一，經濟上實行均田製和租庸調製，使農民有可能安定生産，耕作有時，促進了經濟的發展。
第二，政治上實行三省六部製和科舉製。三省六部製的實行，使宰相的人數比秦漢時期增多，便於皇帝控製。
第三，唐太宗時期加強了國內漢族與少數民族的聯繫，加強對西北等地區的管轄，另外還加強了與亞洲各國的友好往來。
第四，唐太宗善於用人和納諫，這既是“貞觀之治”形成的原因之一，也是“貞觀之治”的內容之一。他重用房玄齡、杜如晦、魏徵、長孫無忌等能臣。
第五:重視農業,減輕農民賦稅勞役."戒奢從簡",節制自己的享受欲望;革除"民少吏多"的弊政,利於減輕人民的負擔.
【天可汗之路】
唐朝是中國歷史上一個最意氣風發的時代，這個“大有鬍氣”的朝代中，邊疆戰爭之頻繁和戰勝次數之多，在中國古代史上非常罕見。所以衹有唐朝才能誕生專門的邊塞詩派，誕生像“年年戰骨埋荒外”這
樣的詩句。而至於“漢傢旌幟滿陰山,不遣鬍兒匹馬還，願得此生長報國，何須生入玉門關？”，“大漠風塵日色昏，紅旗半捲出轅門。前軍夜戰洮河北，已報生擒吐𠔌渾”，“青海長雲暗雪山，孤城遙望玉門關。黃沙百戰穿金甲，不破樓蘭終不還”，“葡萄美酒夜光杯，欲飲琵琶馬上催。醉臥沙場君莫笑，古來徵戰幾人回？”這種豪言壯語，則由於後世朝代偃武修文的風氣，甚至成為了古代史上中國人尚武精神的絶響。尤其是貞觀年間，大唐帝國四面出擊，金戈鐵馬，氣吞萬裏如虎。
第一個時期，唐太宗時期，全面擴張，四面出擊。
貞觀年間是唐朝拓邊最猛烈的時期，也是獲勝最大的時期。貞觀年間，唐朝依次取得了對東突厥、吐蕃、吐𠔌渾、高昌、焉耆、西突厥、薛延陀、高句麗、龜茲甚至可能還包括印度用兵的勝利。這些勝利奠定了唐朝300年的基業。頡利可汗恐怕是有史以來第一個被中國軍隊活捉的草原帝國最高統治者。唐軍出擊定襄，痛殲突厥，活捉頡利可汗，也是唐朝歷史上拓邊戰爭中最輝煌的勝利。頡利可汗被抓到長安。突厥是唐朝最大的邊患，作為同時存在的兩個超級大國之一遭到毀滅，建立單極世界就變得容易多了。唐朝的另一個著名將領候君集奉命帶兵修理驕橫的吐蕃人。候君集通過夜襲擊敗了吐蕃軍，斬首千餘。吐蕃軍退兵後，鬆贊幹布做了頡利可汗也做過的事：派使者謝罪求和。但是他沒有放棄和親的請求。可能是被他的執着感動，7年後他的要求終於得到了滿足。貞觀十五年（641年），文成公主入藏。貞觀八年(634)，吐𠔌渾犯唐，唐軍再次遠征，途中缺水，就刺馬飲血，終於襲破可汗伏允的牙帳，伏允丟下老婆孩子溜之大吉，不久在沙漠中被部下所殺。吐𠔌渾從此被納入唐朝的勢力範圍。貞觀十三年，高昌國失臣禮。高昌王麴文泰看到唐兵來得那麽快，嚇得大病起來，感到忽冷忽熱，幾天後竟然一命嗚呼，由此作為第一個被唐軍活活嚇死的人而載入史册。
第二個時期，徵戰高句麗
高句麗雖然嚮新成立的唐朝朝貢，但實際上卻對唐朝持懷有敵視態度。到後來唐朝第二代皇帝唐太宗李世民的時候，為援助處於高句麗和百濟圍困中的新羅（《新唐書》：“（百濟）與高麗聯合伐新羅，取四十餘城。發兵守之，又謀取棠項城，絶貢道”,新羅告急）,並統一被高句麗據有的遼東地區（當時的“遼東”的概念略同於漢朝四郡的範圍，即中國東北遼河以東地區以及朝鮮半島的北部），唐太宗徵討高句麗，放話給薛延陀：我們父子都要去打高句麗，長安空虛，你要是想犯賤衹管放馬過來！這麽生猛的話，薛延陀當時就嚇得氣短了一截（《舊唐書》載後來高句麗用厚利誘惑薛延陀叛唐，但是“夷男氣懾不敢動”）。
貞觀十九年（645年），唐軍嚮遼東進軍。唐太宗在路上對手下人說，四方基本安定了，就剩下這一塊地方了，趁着我還沒死，良將們還有精力，一定要解决掉。
夏季，徐世績暗渡陳倉，突然出現在遼東城下，高句麗士兵大駭。營州都督張儉和優秀將領李道宗也率兵進入遼東，擊敗高句麗兵，斬首數千。四月，唐軍攻破高句麗蓋牟城，俘虜兩萬多人，繳獲糧食十多萬石。五月，另一路唐軍從山東渡海攻破高句麗卑沙城，俘虜八千人。上百年來中國軍隊第一次得以在鴨緑江邊閱兵。
不久，李績和李道宗所部進逼遼東城下。高句麗軍數萬來援。有人建議說高句麗軍多唐軍少，應該堅守。可是李道宗說高句麗人仗着人多以為我們不敢拿他們怎麽樣，我們就是要攻擊他們，殺殺他們的銳氣。李績說我們被派來就是負責替皇上掃馬路的。現在馬路不幹淨，我們怎麽能躲呢。於是唐軍處於劣勢卻猛烈出擊，高句麗兵始料不及，被衝亂陣型大敗而歸。唐太宗大軍兵到後，把遼東圍得水泄不通，日夜攻打。乘着颳南風的機會，唐太宗指揮士兵點燃城池西南樓，順風放火。高句麗軍抵擋不住了，遼東陷落。唐軍殺高句麗兵一萬多人，俘虜一萬多人，此外還有百姓四萬多人。
攻剋遼東後，唐軍繼續嚮白岩城進發。烏骨城派兵一萬支援，被唐軍擊退（此戰唐軍衹用了800 人）。六月，白岩城不戰而降。唐軍繼續嚮安市進發。高句麗將領高延壽等人率領靺鞨、高句麗兵十五萬來救援，被擊敗。高延壽嚮唐軍乞降，來到唐軍軍營，一進門就跪下，挪動膝蓋嚮前，拜伏在地。（《資治通鑒》上說“延壽、惠真帥其衆三萬六千八百人請降，入軍門，膝行而前，拜伏請命。”）唐太宗對他們說：“東夷少年，跳梁海麯……自今復敢與天子戰乎？”高延壽等人“皆伏地不能對”。唐太宗將降軍中的高句麗軍官、酋長三千餘人虜往中原，其餘高句麗人悉數釋放。
安市城小而堅，在城主楊萬春的抵抗下，唐軍圍攻數月不剋。長孫無忌以為：‘天子親徵，異於諸將，不可乘危徼幸。今建安、新城之虜，衆猶十萬，若嚮烏骨，皆躡吾後，不如先破安市，取建安，然後長驅而進，此萬全之策也。’”）而這種方式過去一直是唐軍剋敵製勝的法寶。最終唐太宗决定暫時停止這次出徵。9月，唐軍班師。這次徵伐高句麗，攻剋玄菟、橫山、蓋牟、磨米、遼東、白岩、卑沙、麥𠔌、銀山、後黃十城，遷徙遼、蓋、岩三州戶口入中國七萬人。新城、建安、駐蹕三大戰，斬首四萬餘級。在唐軍，戰士陣亡的約2000人，損失最大是戰馬，損失了七八成。
此戰雖重創高句麗，但是戰事曠日持久，耗費巨大，最終卻未能滅亡高句麗。因此，唐太宗認為這戰屬於戰敗了，痛心地說：如果魏徵還活着，肯定不會讓我進行這次遠征。但這戰的意義還是比較重大的。這是自三國時期毋丘儉攻破高句麗屠王城以來上百年中國軍隊第一次真正戰勝高句麗人，收復了今天遼寧一帶很多南北朝時期被高句麗奪取的土地，為今後唐朝徹底徵服朝鮮打下了基礎。
貞觀二十二年（648年），倒是有個印度的小插麯。王玄策作為唐朝的使者去印度。中天竺大臣那伏帝阿羅那順篡位，劫持唐使。王玄策衹身逃到吐蕃，藉來吐蕃軍和尼泊爾軍嚮印度進發。連戰三天，印度軍大敗。唐軍斬首三千餘級，水中淹死印度兵約萬人。阿羅那順棄城逃跑，副使蔣師仁追上並俘虜之。此外虜男女一萬二千人，牛馬三萬餘匹。
【地緣戰略思想】
唐太宗地緣戰略思想，是唐太宗關於地緣戰略問題的理性認識，是唐太宗利用唐王朝與周邊少數民族政權之間的地緣關係及其作用法則謀取和維護唐王朝利益的戰略思想。唐太宗地緣戰略思想是中國古代地緣戰略思想的重要組成部分，既有不同於西方也不同於現代的獨具特色的思想內容。
唐太宗在位期間國土廣大，邊界綫綿延麯折，地緣形勢復雜，並隨時間推移而發展變化。歷觀這一時期唐與周邊所發生的諸多地緣關係，既有與唐軍事利益攸關的，也有與唐政治、外交利益攸關的，還有與唐經濟利益攸關的，更多的則是幾種利益兼而有之，錯綜復雜。唐太宗比較成功地處理了與突厥、吐蕃、高昌及西域諸國、高麗、新羅、百濟等國之間的關係。唐太宗的地緣戰略思想正是在處理與周邊地緣關係的實踐過程中逐步産生、發展並走嚮成熟的。
唐太宗地緣戰略思想既具有鮮明的時代特色，又具有他個人的獨有特色，兩者巧妙地融合在一起，貫穿於他的地緣戰略思想的始終。
唐太宗地緣戰略思想的特色主要有以下幾點：一是積極進取。這是唐太宗地緣戰略思想的最顯著的特色，也是其思想中最成功、最可取的地方。唐太宗的雄大豪邁是歷代許多帝王所不可比擬的，這也是他取得成功不可或缺的因素。二是靈活應對。唐太宗在重大變故面前不驚慌失措，他能夠依據客觀形勢和對象的變化而變化，從而較大程度地保證了决策的正確性。三是冷靜務實。唐太宗鑒於隋亡教訓，努力剋服以往帝王急功近利、窮兵黷武的缺陷，註意結合現實需要，量力而行，在冷靜分析的基礎上推行務實政策。四是措置有序。無論是北擊突厥，還是西平高昌，尤其是經略西域，都是先急後緩、由近及遠，有條理、有次序地進行，從中亦可見唐太宗地緣戰略决策之成熟。
唐太宗地緣戰略思想是其軍事思想的重要組成部分，不僅在理論上取得了突破，達到了一個新高度，更重要的是在實踐中獲得巨大成功，業績斐然。史載：“（貞觀十四年）唐地東極於海，西至焉耆，南盡林邑，北抵大漠，皆為州縣，凡東西九千五百一十裏，南北一萬九百一十八裏。”（《資治通鑒》唐太宗貞觀十四年九月。）唐太宗的突出成就正在於他以超越前人的英武雄邁之氣魄，重新開拓了中華民族的疆土，為後來中國版圖的確定作出了重大的貢獻。而這一輝煌業績的獲得，是與唐太宗的地緣戰略思想密切不可分的。即使今天看來，唐太宗的地緣戰略思想裏面也不乏可取之處。
唐太宗地緣戰略思想包含豐富的內容，主要有以下幾點：
（一）着眼於爭奪關中、鞏固“中國”的固本思想。其中居重馭輕的關中本位思想，乃是唐太宗成就帝業的“根本”，也是其地緣戰略思想的出發點。 太宗“深根固本，治安中國”之思想，既有傳統政策沿襲之因素，又有出於當時初唐政治、經濟背景考慮之因素，特別是對地緣因素的考慮，為鞏固政權、密切中外關係、發展經濟進而增強國力而不得不為之。
（二）以夷製夷、保藩固圉的地緣藩屏思想，主要體現在以“懷輯”政策綏納歸附民族，並將其內徙安置在唐周邊地區的一係列行為上，從而達到令其“世作藩屏”的目的。
唐太宗的地緣藩屏思想主要有如下兩個內容：
１置內屬少數民族政權於周邊，以作藩屏。
２在唐周邊地區扶植親唐政權，以作藩屏。
（三）縱橫捭闔的地緣製衡思想。
其主要內容有：①遠交近攻，各個擊破，如聯薛延陀製突厥。②扶弱抑強，保持地區勢力均衡，如聯新羅攻高麗、百濟以及聯合鐵勒諸部扼製薛延陀。③聯近抗遠，服近懾遠，穩定近鄰以攻擊或威懾遠方政權，如聯合吐𠔌渾以對付吐蕃。④另外，唐太宗還有針對某一特定政權內部製定的製衡思想，旨在分化瓦解其勢力，造成內部爭權奪利，削弱統治實力，這尤其體現在對薛延陀的問題上。
唐太宗實行地緣製衡的策略思想及其基本情況大致有如下幾種：
１遠交近攻，拉攏與孤立並用——唐與東突厥、 薛廷陀的地緣製衡關係。
２扶弱抑強，保持地區均勢。
【太宗爭議】
我們都知道，李世民也是人，人無完人，是人就有錯誤。貞觀後期，唐太宗開始有了一些變化，先從納諫開始體現出來。貞觀十年（636年），魏徵發現他“漸惡直言”，這是唐太宗走嚮一些錯誤的開始。
一是徵伐高句麗，這個被某些人認為是錯誤的舉動，但是，就當時形勢來看，此徵是必要的和需要的。第一，發動戰爭的責任是高句麗，高句麗悍然進攻唐朝附庸國新羅挑起戰端，為了維護權威，唐需要發動戰爭來保護自己的附屬國的利益。第二，戰爭中，唐軍是正義和人性的，這也是保證唐軍損失非常小的一個外在條件，在唐軍攻占的城池中，均擁護唐軍。但是由於為了保持正義性和人性化，導致偏求穩，而使戰期拉長。第三，唐軍的撤退和後續戰爭，充分體現了李世民的胸懷和高超的戰略思想，唐軍以2000人的損失消滅高句麗數十萬人，千古罕見。撤退之時，敵將城墻跪拜，也實屬罕見。唐軍後期的軍事騷擾和政治封鎖，使高句麗的實力每況愈下，最終高宗消滅高句麗。
還有奢侈現象的明顯增加。在貞觀十六年的時候，唐太宗下詔說，太子所用之物其他機關不得限製，結果造成太子的嚴重浪費現象。唐太宗自己也開始修造宮殿，貞觀十一年在東都洛陽修飛山宮，二十一年又修翠微宮。這些使唐太宗後期沒有前期勤儉，但是比玄宗，乾隆等不知道要強多少倍。
還有一個大的錯誤就是參與史官所寫的起居註當中。這是專門寫皇帝日常生活和朝政言論的，皇帝無權干涉，這是歷來的傳統，歷來的皇帝都沒有看，尊重史官的職權和地位。而史官也是公正直書，從不掩飾什麽，從不害怕皇帝打擊報復。但唐太宗這個名君卻犯了一個頗大的歷史錯誤，影響幹預了史官的公正性。當然，沒有任何完整證據表明太宗大量歪麯歷史。同時，不僅僅是太宗，自春秋，看史者何止數百，董狐直筆，陳壽索賄，太史被宮，不要說清朝的文字獄了，另外，許敬宗對李世民並沒有好感，這樣表明，唐初歷史應該具有可信度的。
唐太宗在貞觀初期不顧大臣魏徵和李大亮的勸阻，對歸順的北方遊牧民族部落要土地給土地要物資給物資，結果這些部落享受夠唐朝的恩惠後胃口反而越來越大，索性就叛亂了。
後來唐太宗也自己檢討：“中國百姓，實天下之根本，四夷之人，乃同枝葉，擾其根本以厚枝葉，而求久安，未之有也。初不納魏徵言，遂覺勞費日甚，幾失久安之道。”
貞觀二十年（646年），遼東戰役回來時，唐太宗得病，此後一直調養，由此開始服用方士提煉的金石丹藥。先前唐太宗還曾經嘲笑秦皇漢武迷戀方術和尋求丹藥，現在自己也不由自主地陷進去了。貞觀二十一年（647年），唐太宗又得了“風疾”，煩躁怕熱，便讓人在驪山頂峰修翠微宮，第二年，派人從中天竺求得方士那羅邇娑婆寐，病情不斷惡化。貞觀二十三年（649年）五月己巳（二十六）日（7月10日）駕崩於含風殿，享年五十二歲。
【後妃子女】
皇后
長孫皇后
唐朝著名的賢後，中國歷史上最偉大的皇后之一，當代歷史學家評論最知性的皇后。秦王妃期間，衆臣屬就莫不感激，在皇后位，治理後宮井井有條，對貞觀政策路綫頗有影響，早逝，太宗皇哀傷不已，常舉目遠眺昭陵，自後未再立皇后，皇后生幼子幼女晉王和晉陽公主被太宗親自帶在身邊撫養，太宗崩，與皇后同葬一穴，開創帝後合穴先例。
有人說：一個偉大的男人背後站着一個偉大的女性。唐太宗大治天下，盛極一時，除了依靠他手下的一大批謀臣武將外，也與他賢淑溫良的妻子長孫皇后的輔佐是分不開的。
妃嬪
韋貴妃 字澤
楊貴妃 楊妃，生趙王李福，為與隋煬帝女楊妃區別被現代人稱小楊妃，貴妃應為死後追封。
徐賢妃 徐惠，帝崩，哀慕成疾，不肯進藥，曰：“帝遇我厚，得先狗馬侍園寢，吾志也。”復為詩、連珠以見意。永徽元年卒，年二十四，贈賢妃，陪葬昭陵石室。
燕德妃 燕妃
楊妃 隋煬帝女
陰妃 後降為嬪
韋昭容 韋尼子
楊婕妤 楊恭道第三女
蕭美人 蕭鑠第二女
崔才人 崔宏道長女
蕭才人 蕭鏗第二女
武才人 武則天
楊氏 李元吉之妻
王氏
子
太子李承乾（母長孫皇后,太宗皇子中最為彪悍聰穎者，因謀反被廢）
楚王李寬（母不詳，早薨）李寬，過繼叔父楚哀王李智雲。早逝。貞觀初追封，無後，國除。
吳王李恪（母隋煬帝之女楊妃）有文武纔，唐高宗時期被冤殺。
魏王李泰（母長孫皇后，太宗皇子中最為博學者，最受寵愛者，因爭皇位被貶，高宗年間備受尊崇）（619年―652年）字惠褒，永徽三年（652年）死於鄖鄉縣，時年34歲。
齊王李佑（母陰妃，後廢為庶人）
蜀王李愔（母隋煬帝女楊妃，李恪同母弟，李世民稱其不如禽獸。李恪被害，徙居巴州。）
蔣王李惲（母王氏）
越王李貞（母燕妃）
高宗李治（原為晉王，母長孫皇后，皇子中唯一被太宗親自撫養長大者）
紀王李慎（母韋妃）
江殤王李囂（母燕妃，早薨）
代王李簡（母不詳，早薨）
趙王李福（母楊妃）
曹王李明（母楊氏）
女
襄城公主
汝南公主 李宇
南平公主
遂安公主
長樂公主 李麗質（母長孫皇后，出嫁時因太宗要給的嫁妝倍於長公主而被魏徵諫）
豫章公主（長孫皇后養女）
巴陵公主（下嫁柴令武），下嫁柴紹與平陽公主之子柴令武，永徽四年與房遺愛謀反，被唐高宗賜死。顯慶中追贈為北景公主
普安公主
東陽公主
臨川公主 李孟薑（母韋貴妃）
清河公主 李敬
蘭陵公主 李淑
晉安公主
安康公主（關於安康公主，唐史衹有一句話：“安康公主，下嫁獨孤謀。”）
新興公主
城陽公主（母長孫皇后）
高陽公主（合浦公主）
金山公主
晉陽公主 李明達（母長孫皇后，公主中唯一被太宗親自撫養長大者，為太宗最為喜愛的女兒，多受衆臣喜愛，早薨，有其母風）
常山公主
新城公主（母長孫皇后，初封衡山公主）
【主要詩作】
【賜房玄齡】
太液仙舟迥，西園引上纔。未曉徵車度，雞鳴關早開。
【賜蕭瑀】
疾風知勁草，板蕩識誠臣。勇夫安識義，智者必懷仁。
【遼城望月】
玄菟月初明，澄輝照遼碣。映雲光暫隱，隔樹花如綴。
魄滿桂枝圓，輪虧鏡彩缺。臨城卻影散，帶暈重圍結。
駐蹕俯丸都，伫觀妖氛滅。
【飲馬長城窟行】
塞外悲風切，交河冰已結。瀚海百重波，陰山千裏雪。
迥戍危烽火，層巒引高節。悠悠捲旆旌，飲馬出長城。
寒沙連騎跡，朔吹斷邊聲。鬍塵清玉塞，羌笛韻金鉦。
絶漠幹戈戢，車徒振原隰。都尉反竜堆，將軍旋馬邑。
揚麾氛霧靜，紀石功名立。荒裔一戎衣，靈臺凱歌入。
【經破薛舉戰地】
昔年懷壯氣，提戈初仗節。心隨朗日高，志與秋霜潔。
移鋒驚電起，轉戰長河决。營碎落星沉，陣捲橫雲裂。
一揮氛沴靜，再舉鯨鯢滅。於茲俯舊原，屬目駐華軒。
沉沙無故跡，減竈有殘痕。浪霞穿水淨，峰霧抱蓮昏。
世途亟流易，人事殊今昔。長想眺前蹤，撫躬聊自適。
【還陝述懷】
慨然撫長劍，濟世豈邀名。星旂紛電舉，日羽肅天行。
遍野屯萬騎，臨原駐五營。登山麾武節，背水縱神兵。
在昔戎戈動，今來宇宙平。
【出獵】
楚王云夢澤，漢帝長楊宮。豈若因農暇，閱武出轘嵩。
三驅陳銳卒，七萃列材雄。寒野霜氛白，平原燒火紅。
雕戈夏服箭，羽騎緑沉弓。怖獸潛幽壑，驚禽散翠空。
長煙晦落景，灌木振嚴風。所為除民瘼，非是悅林叢。
【元日】
高軒曖春色，邃閣媚朝光。彤庭飛彩旆，翠幌曜明璫。
恭己臨四極，垂衣馭八荒。霜戟列丹陛，絲竹韻長廊。
穆矣熏風茂，康哉帝道昌。繼文遵後軌，循古鑒前王。
草秀故春色，梅豔昔年妝。巨川思欲濟，終以寄舟航。
【喜雪】
碧昏朝合霧，丹捲暝韜霞。結葉繁雲色，凝瓊遍雪華。
光樓皎若粉，映幕集疑沙。泛柳飛飛絮，妝梅片片花。
照璧臺圓月，飄珠箔穿露。瑤潔短長階，玉叢高下樹。
映桐珪纍白，縈峰蓮抱素。斷續氣將沉，徘徊歲雲暮。
懷珍愧隱德，表瑞伫豐年。蕊間飛禁苑，鶴處舞伊川。
儻詠幽蘭麯，同歡黃竹篇。
【編年紀事】
貞觀元年（六二七）正月初一，改元貞觀。
貞觀元年（六二七）正月，唐太宗下製，令今後中書省、門下省以及三品以上官入閣商議國傢大事，都要有諫官跟隨，遇有不當之處，諫官立刻進諫。
貞觀元年（六二七）正月，唐太宗命吏部尚書長孫無忌等與學士、法官等人重新議定律令。放寬絞刑五十條為砍斷有趾，唐太宗仍嫌這種肉刑太殘酷，蜀王法曹參軍裴弘獻請再改為加役流，徙三千裏，居作三年。詔從之。
貞觀元年（六二七）唐天節將軍、燕郡王李藝據涇州反。
貞觀元年（六二七）二月，並省全國的州縣，將全國分為十道，即關內道、河南道、河東道、河北道、山南道、隴右道、淮南道、江南道、劍南道、嶺南道，廢郡為州，故每道各轄若幹州。
貞觀元年（六二七）十月嶺南酋長馮盎遣子入朝
貞觀元年（六二七）末，吏部侍郎劉林甫奏請以後四時聽選，隨闕註擬，人以為便。太宗詔命一部分人到洛州參選。太宗說“官在得人，不在員多。”命房玄齡並省中央官員，衹留下文武官額六百四十三人。
貞觀二年（六二八），詔各地置義倉。薛延陀首領夷男受唐封為可汗，建汗庭於漠北。
貞觀二年（六二八）三月，大理少卿鬍演嚮太宗上報每月囚徒的賬目。太宗命令後大辟罪由中書、門下省四品以上官和尚書省議定，以免冤濫。接着又逐個帶進囚徒，輪到岐州刺史鄭善果時，太宗認為善果雖有罪，官品不低，不應與於囚徒之列。於是，又命以後三品以上官犯罪，不用帶進，可在太極宮承天門左右朝堂聽判决。
貞觀二年（六二八），關內發生旱災，百姓缺糧，有許多人賣兒賣女以換取衣糧。四月，太宗詔出禦府金帛贖回被賣兒童，交還父母。又因去年久雨，今年又遭受旱災、蝗災，大赦天下。
貞觀二年（六二八）四月，突利派使來唐請求援助。太宗召集大臣討論，兵部尚書杜如晦請出兵攻突厥。貞觀三年（六二九）十二月，突利可汗入朝，太宗任命他為右衛大將軍，賜爵北平郡王。
貞觀二年（六二八）九月，中書捨人李百藥請再出宮人。唐太宗命尚書左丞戴胄和給事中杜正倫在掖庭西門簡選宮人，前後放出宮女又達三千餘人。
貞觀二年（六二八）末，派遣遊擊將軍喬師望從小路帶着册書拜夷男為真珠毗伽可汗，賜給他鼓纛。夷男非常高興，派使入貢。
貞觀三年（六二九）三月，太宗以房玄齡為左僕射，杜如晦為右僕射，以尚書右丞魏徵守秘書監，均參與朝政。房玄齡善謀略，杜如晦善决斷，為唐朝名相，並稱“房杜”。
唐朝初年，凡國傢軍政大事，中書捨人各依自己的見解，簽署自己的名字，被稱做五花判事。由中書侍郎、中書令審查，由給事中、黃門侍郎校正。貞觀三年（六二九）四月，唐太宗重新申明舊的制度，於是很少發生錯事。
貞觀三年（六二九）大旱，太宗詔求直言，常何代馬周嚮太宗提了二十多條意見。太宗大喜，招馬周入見，令他宿直門下省，不久以馬周為監察御史，終至拜相。
貞觀三年（六二九）八月，命兵部尚書李靖為行軍總管、張公謹為副總管，前去徵討突厥。突厥俟斤九人帶領三千騎兵降唐，拔野古、僕骨、奚等酋長也帥部衆降唐。
貞觀三年（六三〇）閏十二月，東謝酋長謝元深、南謝酋長謝強朝唐。東謝、南謝是南蠻的分支，分佈在黔西。唐太宗下詔以東謝之地為應州（今貴州德江縣貞觀三年（六三〇）閏十二月，牂牁酋長謝能羽及兗州蠻嚮唐入貢。太宗詔以牂牁之地為牂州。党項酋長細封步賴降唐，唐以其地為軌州境），南謝之地為莊州（今貴州境內），隸屬於黔州都督
貞觀四年（六三〇）正月，李績在白道敗突厥，李靖在陰山大敗頡利可汗。
貞觀四年（六三〇）正月，李靖率三千騎自馬邑進駐惡陽嶺，夜襲定襄，大敗突厥。頡利可汗大驚，遷牙帳於磧口。頡利的親信康蘇密以隋煬帝後蕭氏及其孫楊政道降唐。
貞觀四年（六三〇）三月，各族君長都到長安請唐太宗稱天可汗，唐太宗笑道：“我為大唐天子，難道又為可汗之事嗎？”但此後唐太宗賜給西北各族君長的璽書都用“天可汗”的稱號。
貞觀四年（六三〇）三月，唐行軍副總管張寶相突至蘇尼失兵營，俘頡利，送往長安。
貞觀四年（六三〇）九月，伊吾城主到長安朝唐。先是伊吾內屬，隋於其地設置伊吾郡；隋末，城主嚮突厥稱臣。頡利被唐攻滅後，伊吾城主率他所屬的七城降唐，唐朝在伊吾設置西伊州（今新疆哈密）。
太宗閱讀中醫著作《明堂針灸書》後，認為人的五髒都歸結在背部。於是於貞觀四年（六三〇）十一月下令，此後審訊犯人，不得鞭擊背部。
貞觀四年（六三〇），全國豐收，流散到各地的百姓回歸故裏，米每鬥不超過三、四錢，一年僅判處了二十九人死刑。
貞觀四年（六三〇）八月，日本遣使犬上三田耜（亦作禦田鍬）、藥師惠日等來唐，是為日本第一次遣唐使。
貞觀五年（六三一），開党項之地為十六州。日本第一次遣唐使犬上禦田鍬等至唐（奉使在上年）。林邑、新羅都遣使到唐。
貞觀五年（六三一）十二月初二日，唐太宗製：“判决死罪，要在兩天內五次申奏，下各州的要三次申奏；行刑當天，尚食局不得進酒肉，內教坊及太常寺不得奏樂。門下省還要再檢查，有依法應當死而處境堪憐者，另外寫狀上奏。”五次申奏是指行刑前兩天到行刑之日共上奏五次，人命關天，以示慎重。衹有犯惡逆罪（隋立“十惡不赦”之科，唐承之）的人衹奏一次。
貞觀六年（六三二），太宗乃止。增置三師官（太師、太傅、太保）。太宗與侍臣論安危之本。長孫後賀太宗喜得諫臣，焉耆王遣使入貢，唐太宗派鴻臚少卿劉善因前去册立泥孰為奚利邲咄陸可汗。
貞觀六年（六三二）十一月，契苾（鐵勒十五部之一）部落酋長契苾何力率所部六千余家到沙州（今甘肅敦煌西）嚮唐政府歸降。
貞觀七年（六三三），太宗赦死囚，李淳風造渾天黃道儀。
貞觀八年（六三四），李靖等赴諸道察情。
貞觀九年（六三五），唐高祖李淵駕崩，享年70歲，唐平吐𠔌渾。
貞觀十年（六三六），唐建南北衙。
貞觀十年（六三六）六月二十一日，太宗皇后長孫氏卒，享年三十七歲。
貞觀十一年（六三七）八月，侍御史馬周上疏朝廷，建議政府應重視州縣地方官吏的選任。太宗聞奏，深以為是，决定以後刺史由他親選，縣令則由京官五品以上各舉一人。
貞觀十二年（六三八）立薛延陀小可汗，太宗建百騎。
貞觀十三年（六三九）太宗停世襲刺史。
貞觀十四年（六四〇）流鬼國遣使入貢， 侯君集滅高昌，唐置安西都護府於交河，禮官改禮製，唐文成公主入藏。
貞觀十五年（六四一）唐蕃和親，席君買平吐𠔌渾之亂，册封百濟王，李世績敗薛延陀。
貞觀十六年（六四二）魏王泰上《括地志》，太宗徙死罪者實西州，禁自傷肢體，郭孝恪敗西突厥咄陸可汗。
貞觀十七年（六四三）魏徵卒，享年64歲。徵高句麗，李世民命畫功臣像於凌煙閣，太子李承乾造反，被廢，立晉王李治為皇太子。
貞觀十八年（六四四）太宗親徵高句麗。
貞觀十九年（六四五）鐵勒九姓大首領率衆降唐。 玄奘取經回國，張亮、程名振拔高麗卑沙城，李世績攻高麗遼東城，契苾何力等勇擊高麗，高麗白岩城降，太宗破高麗安市救兵，太宗下詔從高麗班師。
貞觀二十年（六四六） 薛廷陀咄摩支降唐，敕勒諸部朝唐。
貞觀二十一年 （六四七）唐發兵攻龜茲，太宗哭高士廉，骨利幹入貢，王波利造船攻高麗，突厥車鼻可汗嚮唐朝入貢，西趙酋長趙磨內附。
貞觀二十二年（六四八）薛萬徹等率軍擊高麗，李百藥卒，結骨入朝，鬆外蠻附唐，契丹首領麯據內附，阿史那賀魯降唐，王玄策破中天竺，房玄齡病逝，享年70歲。
貞觀二十三年 （六四九）徒莫祗等蠻內附。
貞觀二十三年（六四九）五月，唐太宗病危。臨終前，他召見長孫無忌和褚遂良，讓他們輔佐太子治聽政。同月己巳日，太宗駕崩於翠微宮含風殿，享年52歲。太子李治即位，是為唐高宗。他是歷史上最為偉大的皇帝之一。
【太宗丞相】
蕭瑀(626年，627年，630年，643年-646年)
陳叔達(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)
房玄齡(626年-643年，643年-648年)
長孫無忌(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)
魏徵(629年-643年)
溫彥博(630年-637年)
戴胄(630年-633年)
侯君集(630年-632年，632年-643年)
楊師道(636年-643年，645年)
劉洎(639年-645年)
岑文本(642年-645年)
李世績(643年-649年)
張亮(643年-646年)
馬周(644年-648年)
褚遂良(644年-647年，648年-649年)
許敬宗(645年)
高季輔(645年)
張行成(645年)
崔仁師(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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