Background

Su Dingfang was born in 591, during the reign of Emperor Wen of Sui. Toward the end of the reign of Emperor Wen's son and successor Emperor Yang of Sui, the empire was engulfed in agrarian rebellions, and Su Dingfang's father Su Yong (蘇邕) led a local militia in combating the agrarian rebels. Su Dingfang was then in his teenage years, and often served as part of Su Yong's forward troops. After Su Yong died, Su Dingfang took over the militia and continued to battle the agrarian rebels. According to Su Dingfang's biography in the Old Book of Tang, he was the one who defeated and killed one of the major rebel generals, Zhang Jincheng, in battle. He also defeated another rebel general, Yang Gongqing.

Su Dingfang later followed the rebel ruler Dou Jiande the Prince of Xia, and he was particularly favored by Dou's major general Gao Yaxian (高雅賢), who treated him like a son. After Dou was defeated and captured by the Tang Dynasty general Li Shimin the Prince of Qin (the later Emperor Taizong) in 621, Xia domain was initially taken over by Tang, but Gao and a number of other former Xia generals rose later in the year, supporting the Xia general Liu Heita as the Prince of Handong, and Su served Liu in this campaign of resistance as well. After Gao's death in battle in 622, followed by Liu's defeat by Tang's crown prince Li Jiancheng (Li Shimin's older brother) in 623, Su returned to his home territory.

Sometime after 626 (after Li Shimin became emperor, succeeding his father Emperor Gaozu), Su became a military officer under the prominent general Li Jing. In Li Jing's campaign against Eastern Turkic Khaganate in 629–630, in the final decisive battle where Li Jing crushed the forces of the Jiali Khan Ashina Duobi and killed his wife (Sui's Princess Yicheng) in battle, Su served as Li Jing's forward commander. After Li Jing returned to the Tang capital Chang'an victoriously, Su was promoted to a mid-level officer position.

Initial service during Emperor Gaozongs reign

Little is known about Su Dingfang's career during Emperor Taizong's reign, but as of 655, during the reign of Emperor Taizong's son Emperor Gaozong, six years after Emperor Taizong's death, Su was still described to be at the same rank as he had achieved after the victory over Ashina Duobi. That year, Su served under the general Cheng Minzhen (程名振) in a campaign to harass the border territory of Goguryeo.

Later that year, Emperor Gaozong had the general Cheng Zhijie (程知節) command an army against Western Turkic Khaganate's Shabolüe Khan Ashina Helu, who had previously been a Tang vassal but who had broken away. Su served under Cheng in this campaign. Cheng's campaign was initially enjoying some success against Western Turks' vassal tribes Karluks (歌暹祿), Chuyueh (處月), Turgesh (突騎施), and Chumukun (處木昆). Around the new year 657, Cheng's forces had finally encountered Western Turks' main forces, and initial engagements, where Su led the forward troops, resulted in a victory. However, Cheng's deputy Wang Wendu (王文度) was jealous of Cheng, and ordered that, instead of immediately engaging the rest of Western Turks' troops, as Su advocated, that the forces should be put into a rectangular formation, with the military supplies in the middle. Wang further falsified an order from Emperor Gaozong, transferring the command of the forces from Cheng to him. Su warned Cheng that Wang's refusal to engage Western Turks forces immediately would cause Tang forces to be worn out and pointed out that the order to put Wang in charge must be a forgery—suggesting that Cheng immediately put Wang under arrest and engage Western Turks. Cheng refused. Subsequently, when some Western Turk people surrendered, Wang, in avarice over their property, slaughtered them and took over their property, over Su's objections, and when Wang subsequently gave some of the property to Su, Su refused to accept. At some point, for reasons unknown, Tang troops withdrew, and Wang was discovered to have forged the imperial order, but was only reduced to commoner rank.

Campaign against Western Turks

In spring 657, Emperor Gaozong again launched a campaign against Western Turks, this time with Su Dingfang in command, assisted by the generals Ren Yaxiang and Xiao Siye (蕭嗣業), along with troops from Tang's ally Huige and also Western Turks chiefs Ashina Mishe (阿史那彌射) and Ashina Buzhen (阿史那步真), who took a southern route relative to Su's main forces, which took a northern route. Su first attacked Chumukun, defeating it. Su soon engaged Ashina Helu's army of nearly 100,000 men, with less than 20,000 men himself. Ashina Helu, believing that he could crush Su's smaller army easily, ordered a charge, but could not break through Su's infantry formation, armed with long spears. Su then counterattacked with cavalry, defeating Ashina Helu and killing and capturing several tens of thousands of men. The next day, as Su continued to advance, the commanders of the five western tribes of Western Turks (which consisted of 10 tribes), including the general Huluwu (胡祿屋), surrendered, and Ashina Helu fled along with his general Qulü (屈律). The commanders of the five eastern tribes surrendered to Ashina Buzhen.

As Su continued to advance to chase after Ashina Helu, he encountered snow storms, and when his subordinate generals suggested that they halt until the weather got better, Su pointed out that Ashina Helu would be surprised that they were continuing to chase him through the snow and could thus caught be surprised. He joined forces with Ashina Mishe and Ashina Buzhen, and made a surprise attack on the regrouping Ashina Helu, again defeating him and capturing or killing some tens of thousands of men.

Ashina Helu fled to Shi (石國, modern Tashkent), a vassal of Western Turks, but Shi, not willing to risk being attacked by Tang forces as well, captured and turned Ashina Helu over to Tang forces. The independent Western Turkic Khaganate was no more (although from time to time Tang and Tibet would create members of the royal family khans to try to pacify the region—as it immediately tried to do, creating Ashina Mishe Xingxiwang Khan (興昔亡可汗, literally "the khan who would raise what had been destroyed) and Ashina Mishe Jiwangjue Khan (繼往絕可汗, literally, "the khan who will continue what had been ended"), although Ashina Mishe would eventually be falsely accused of treason by Ashina Buzhen and killed, and after Ashina Buzhen's own death soon thereafter, the scheme fell apart).

When Su presented the captured Ashina Helu to Emperor Gaozong, Emperor Gaozong spared Ashina Helu and promoted Su to be a major general. He also created Su the Duke of Xing, while creating Su's son Su Qingjie (蘇慶節) the Duke of Wuyi.

Campaign against Sijie

In 659, a vassal of Western Turkic Khaganate (Pin. Tujue) Duman (都曼), a commander of the Sijie (思結) tribe, rebelled against Tang suzerainty, along with Western Turkic Khaganate subject kingdoms Shule (疏勒), Zhujubo (朱俱波), and Yebantuo (謁般陀) (all in or near modern Kashgar, Xinjiang). The joint forces commanded by Duman quickly defeated the Tang vassal Yutian (于田, in modern Hotan, Xinjiang). In winter 659, Emperor Gaozong sent Su Dingfang against Duman, and once he arrived in the vicinity of Duman's army, he selected 10,000 infantry soldiers and 3,000 cavalry soldiers and made a surprise attack on Duman. When he arrived at Duman's headquarters, Duman was surprised, and after Su initially defeated Duman, Duman was forced to withdraw within the city. Su put the city under siege, and Duman surrendered. In spring 660, Su took Duman back to the eastern capital Luoyang, where Emperor Gaozong was at the time, to present Duman to him. Some officials requested that Duman be executed, but Su made a plea on Duman's behalf that he had promised Duman life before Duman surrendered, and Emperor Gaozong stated that while under the law Duman should die, he would honor Su's promise, and so he spared Duman.

The Old Tibetan Annals, a document in Classical Tibetan that was discovered at Dunhuang in the early 20th century, mentions another battle that Su Dingfang fought against the Tibetans in 659:

"Da Rgyal Mang Po Rjes (Chinese: Dayan Mangbuzhi) fought a battle with Su Dingfang of the Tang at the Dongdai 東岱 (a Tibetan regional administrative unit) of Wuhai 烏海 (southwest of Lake Qinghai). Da Rgyal was killed and his army of 80,000 men was defeated by 1,000 Tang troops."

Unfortunately, this battle is not mentioned in any other Tang or Tibetan sources, and it remains a mystery whether (not to mention where and how) Su Dingfang actually defeated a Tibetan army that was 80 times larger than his own.

Campaign against Baekje

Su Dingfang did not remain inactive. Also in spring 660, Tang's ally on the Korean Peninsula, Silla, sought aid from Tang due to attacks from Baekje. Emperor Gaozong put Su in command of a joint army and navy with 100,000 soldiers to attack Baekje, in joint action with Silla's King Muyeol. In summer 660, Su departed from Chengshan (成山, in modern Weihai, Shandong) and crossed the Yellow Sea to Baekje. Baekje forces tried to prevent Tang forces from landing, but could not. Tang forces directly attacked the Baekje capital Sabi and put it under siege. Baekje's King Uija and his crown prince Buyeo Yung fled to the north, and as he did, his second son Buyeo Tae (扶餘泰) declared himself king. Buyeo Yung's son Buyeo Munsa (扶餘文思) pointed out to his father that this meant that even if they were able to repel Tang forces, Tae would kill them, and therefore surrendered. Many people surrendered with Munsa, and Tae was forced to surrender, along with King Uija and Prince Yung. Emperor Gaozong ordered that Baekje's territory be annexed into Tang. In winter 660, Su presented the captives to Emperor Gaozong in Luoyang, and Emperor Gaozong released King Uija and the rest of the captives and declared a general pardon. (It was noted, however, by historians that after the victory, Su's army mistreated the Baekje people, causing them to support a campaign of resistance started by King Uija's son Buyeo Pung, who returned from Japan to claim the throne and to try to re-establish Baekje, which was not fully suppressed until 663. In particular, two Baekje generals, who later would become major generals for Tang after their eventual submission, Heukchi Sangji (黑齒常之) and Sataek Sangyeo (沙吒相如), were described to have resisted Su in light of pillages and killings carried out by Su's forces and were able to successfully hold out against Su's forces.)

Later activities

In winter 660, Emperor Gaozong ordered Su Dingfang, as well as other generals Qibi Heli (契苾何力), Liu Boying, and Cheng Minzhen to attack Baekje's ally Goguryeo. By fall 661, Su had placed Goguryeo's capital Pyongyang under siege. By spring 662, however, after the general Pang Xiaotai (龐孝泰) was defeated and killed in battle with Goguryeo forces and Su could not capture Pyongyang he, faced with problems of severe snow storms, was forced to withdraw.

In summer 663, Tibet launched a major attack against the Tang vassal Tuyuhun. Emperor Gaozong sent Su to lead an army to aid Tuyuhun, but while there was no further record at that time of the Tibetans being victorious over Tuyuhun, there were also no records that Su was able to stem the Tibetan tide. He died in 667.

Liu Xu, the lead editor of the Old Book of Tang, commented in this way about Su:

生平

早年

蘇定方于大業年間出生，他的父親蘇邕在大業末年率領同鄉數千人為郡里征討賊寇。蘇定方非常勇猛，十五歲的時候跟隨父親一同追討賊寇，常常作為先鋒破陣。在蘇邕去世後，武邑郡太守命蘇定方領兵繼續清剿周圍賊寇。他率軍清剿了位于郡西、南部的張金稱和楊公卿，親手斬殺張金稱並追擊楊公卿二十里路，獲得了很多戰利品，鄉民因此都開始依靠于他。隨後蘇定方加入了竇建德的勢力，深受高雅賢的喜愛並被他收為養子。在竇建德死後蘇定方繼續效力于劉黑闥手下，高雅賢多次為劉黑闥攻城拔寨，蘇定方每次作為先鋒戰鬥都有戰功。武德六年。李建成率軍攻打並斬首了劉黑闥，蘇定方就此回到老家。

征頡利可汗

唐太宗貞觀初年，蘇定方出任匡道府折衝，被徵召參與與突厥的作戰。貞觀三年（629年），蘇定方被李靖派遣為前鋒，率領兩百騎兵，趁著大霧偷襲突厥軍營。他在衝擊過程中看見頡利可汗所在的牙帳並向那裡掩殺過去，致使頡利所部不得不撤退。當李靖率軍趕到後，剩餘的敵軍也都投降了。最後李靖俘虜了包括頡利可汗在內的多位突厥首領，回師後蘇定方也因此被升任為左武候中郎將

唐高宗永徽中，蘇定方官至左衛勛一府中郎將。永徽六年（655年）高句麗聯合百濟、靺鞨進攻新羅，攻占其北境三十餘城。新羅向唐朝遣使求援，蘇定方隨同程名振征討高句麗，五月，蘇定方等渡過遼水，高麗見唐軍兵少，于是渡過貴端水迎戰。蘇定方等奮力進攻，大敗高句麗軍，殺俘一千多人，焚毀其外城、村落後回師。戰後，蘇定方拜授右屯衛將軍，封臨清縣公。

征戰西域

初征西突厥

顯慶元年（656年），左衛大將軍程知節出征西突厥阿史那賀魯，蘇定方因而跟隨出征，被任命為前軍總管。次年十二月，在初戰告捷後，大軍到達鷹娑川（今新疆開都河上游裕勒都斯河谷），西突厥兩萬騎兵前來抵禦唐軍，總管蘇海政率軍與突厥所部接觸，互有勝負。隨後西突厥的分支鼠尼施等又率領兩萬多騎兵前來增援，蘇定方當時正下馬休整。他與突厥軍隊相隔著一座小山嶺，又離程知節所率主力約十里遠，看到遠處塵土飛揚後率領五百名騎兵前去截擊敵軍。突厥軍隊因此軍心潰散，蘇定方率軍追擊了二十里，斬殺敵軍一千五百多人，還獲得了兩千匹馬，而突厥軍隊因潰敗而在戰場上遺留下了非常多的甲冑、武器。

時為副大總管的王文度嫉妒蘇定方的功勞，對程知節建議說：「敵軍雖然逃跑了，官軍死傷也很多。現在應當結成方陣，將輜重安置在軍陣中間，四面列隊，人馬披甲，敵來就迎戰，這才是萬全之策。不要讓士兵輕率離陣，以致造成損傷。」。為使程知節信服，王文度矯旨責怪程知節恃勇輕敵，轉而讓王文度節度所部。于是王文度下令全軍固守原地，不得繼續深入。在王文度的軍令之下，唐軍不得不每天披甲騎馬，戰馬不堪重負，有很多因此而瘦死；騎兵也非常疲勞，不再有戰鬥的意志。見此情況，蘇定方向程知節進言認為如此防守無法立功，遇到敵軍便會潰敗，他進一步指出程知節現在將軍隊事物交由王文度管理是不合理的，要求程知節將王文度先行關押，再上奏于朝廷，然而最後程知節並未聽從他的建議。

後大軍行進至恆篤城，遇到有胡人想要投降歸附。王文度又說：「這些胡人現在投降，等我軍撤回後，他們還會反叛，不如全部殺死，奪取他們的物資錢財。」蘇定方則反駁說：「如果這樣處置，那便是自己當賊，又怎能說是討伐叛逆？」王文度遂又忽視了蘇定方所言，下令處決了那些胡人。等到瓜分財物時，唯獨蘇定方沒有拿任何一點。至十二月，唐軍無功而返，王文度本因擅自矯詔該當判處死刑，後被除名為平民；程知節也因逗遛不前、追擊不力，在減免死刑後，被罷去官職；蘇定方則被轉為右屯衛將軍。

再征西突厥

顯慶二年（657年）正月，蘇定方被擢升為伊麗道行軍大總管，以任雅相、回紇婆潤為副總管，自北道而行，再次征討阿史那賀魯。十二月，蘇定方先是從金山北部進軍，率部打敗了木昆部落，安撫了前來投降的懶獨祿，後率千餘騎兵突進至突騎施部。他率唐軍及回紇僕從軍共萬餘人進擊並抵達了曳咥河，賀魯此時則已經集結了多部兵力共十萬，前來抵禦唐軍。因唐軍人數少，被敵軍所包圍。蘇定方先令步兵于南部高地結陣，持槊向外，他自己則親自率領騎兵列陣于北部的平原。賀魯所部對唐步兵陣地發起了三次衝鋒，卻都被成功防禦住了。蘇定方趁機衝擊了敵軍主力，在敵軍潰敗後又追擊了三十里，最後斬首上萬。

次日，蘇定方率軍繼續進擊，五弩失畢都紛紛投降了唐軍，賀魯及他剩下的數百騎兵被迫向西逃亡。後阿史那步真從南道進軍，聽聞賀魯敗退的五咄陸部落以唐朝為其舊主為理由歸降于步真。蘇定方令其副將蕭嗣業率軍向邪羅斯川出發，追擊賀魯，他則和任雅相率新投降的士卒跟在後面。由于正巧當地下大雪，積雪近三尺，唐軍多位將領請求停止進軍，等到天氣晴朗再做打算。蘇定方卻說敵人預料他們會因為雪深而不再前進，那麼就應該現在追擊，如果緩下腳步則會越追越遠。經過晝夜行軍，蘇定方所部與阿史那步真所部會師于雙河，距離賀魯只有百里之遠，唐軍遂結陣向賀魯牙帳所在的金牙山前進。他們趁賀魯不備，發起了突襲，斬獲了上萬首級。賀魯再次逃脫，率數十騎和咥運一同逃向石國。阿史那彌射的兒子元爽和蕭嗣業合兵一處，捕獲了被石國所獻出來的賀魯，最終蘇定方押解賀魯班師回朝。蘇定方在此戰中先是擒獲了賀魯，又拓展了唐的疆域版圖，因而被升為左驍衛大將軍，封邢國公，他兒子蘇慶節也被封為武邑縣公。

烏海之戰

據敦煌莫高窟中發現的藏文《吐蕃大事紀年》第十條記載，藏曆羊年（唐高宗顯慶四年，公元659年），蘇定方在青藏高原烏海一帶與吐蕃軍展開了一次作戰。此次戰爭沒有被記載在唐朝一方的史料之中。白桂思猜測此役與資治通鑑卷200所說論欽陵攻吐谷渾是同一戰役，但是年代錯亂。才讓《吐蕃史稿》於659-660年只寫吐蕃攻吐谷渾，沒有提到與唐交戰。學者對此役史料解讀（如地點、勝負及兵力）沒有共識，如王堯解讀為唐軍一千擊敗藏軍八萬；更敦群培《白史》解讀為藏軍一千擊敗唐軍八萬；黃正建主張《吐蕃大事紀年》慣例不紀錄吐蕃戰敗，而且漢文文獻沒有蘇定方當年與吐蕃交戰的記載，因此或許是藏軍八萬戰勝唐軍一千的一場小戰役。達延莽布支的身份，胡小鵬認為是烏海一帶親吐蕃的吐谷渾首領，王忠認為是駐守鄯善的慕容尊王。

《吐蕃地名研究》也認為所謂烏海東茹，實際上是位于唐朝隴右道附近的孟達天池，即東茹措那。《道幃藏族社區志》說「達延莽布支大臣率蕃軍，前往董岱措納湖（即冬日措納）一帶，與漢兵（唐軍）交戰，達延莽布支不幸犧牲，部下為了紀念他，將其葬在阿尼達延山，此後，達延莽布支被敬為山神，同時成為具有神力的家鄉神 。」

顯慶四年，鐵勒和疏勒舉兵背叛唐朝，下屬有疏勒（今新疆西南部喀什一帶）、朱具波（今新疆西南部葉城一帶）、喝般陀（又稱蔥嶺國)三國，蘇定方受命對其進行征討。當唐軍行軍至葉葉水時，敵軍在馬頭川已經建立好了防禦工事。於是蘇定方攜三千匹馬跨越帕米爾高原突襲，他們經過一整天的奔襲抵達了敵城西十里處。由于都曼震驚于唐軍的出現，他率部分守軍在城門外試圖阻攔唐軍，卻被打敗，只能退守在城內，而城門則被唐軍順利占領。

等到晚上，唐軍主力陸續抵達，在圍住城池後伐木製作攻城器械。都曼知道他無法避免戰敗的結果，于是自縛投降。蘇定方解送都曼回到了洛陽，在乾陽殿上獻俘于高宗，他因此功被升為左武衛大將軍、加食邑五百戶。

征戰遼東

平滅百濟

顯慶五年（660年）二月十日，蘇定方隨唐高宗巡幸太原。由于百濟依仗有高麗的援助，開始染指新羅疆域，因此新羅王向唐朝發出了求援信。蘇定方遂于三月十日被任命為神丘道行軍大總管，率左驍衛將軍劉伯英等水陸大軍十萬人征討百濟國。又以新羅國王金春秋為嵎夷道行軍總管，率領新羅兵協同唐朝大軍作戰。

蘇定方率軍自城山（今山東省榮成市東部）出發，橫渡黃海，先是抵達了德物島，新羅方面五萬士兵也在金庾信率領下合軍。當時百濟朝廷中佐平義直建議要趁唐軍登陸就截擊，達率常永則想要與唐軍開展持久戰。由于國王猶豫不決，唐、新羅部隊已經穿過了百濟的重要關口白江和炭峴。由于後派遣的五千死士阻攔新羅軍隊不成，百濟軍隊不得不屯兵據守熊津江口（今朝鮮半島南部錦江口），試圖抵抗唐軍。于是蘇定方從東岸登陸，在山下列陣並開始與百濟軍交戰。當唐軍水師抵達時，百濟軍已經戰敗，被斬首數千。水師隨著漲潮與陸軍一同進軍，朝真都城方向出發。當唐軍距離真都城約二十里時，百濟集結國內軍隊前來阻擊。蘇定方遂率軍迎戰，擊敗了百濟軍隊並斬殺一萬餘人，唐軍乘勝攻入外城。

百濟國王扶餘義慈自知無法避免失敗的下場，後悔他沒有聽取忠臣的諫言，帶領太子扶餘隆等人向北境逃去。蘇定方後進軍包圍了百濟都城泗沘城（今韓國忠清南道扶餘郡），義慈的次子扶餘泰自立為百濟王，率眾堅守。義慈的孫子扶餘文思說：「國王和太子雖然都出了城，但依然活著；叔父統領兵馬，就擅自稱王，如果唐軍撤退，我父子性命就無法保全了。」于是文思率其左右親兵翻城向唐軍投降，很多百姓也紛紛跟隨他投降，扶餘泰無法阻止。于是蘇定方趁勢命士卒登上城樓，樹起唐朝的旗幟。城中人心更加惶恐，導致扶餘泰不得不打開城門投降，請求保全其性命。其大將禰植又帶著義慈來降，太子隆與眾城主皆前來奉表歸誠。

八月十五日，在徹底平定百濟後，陵州長史判兵曹賀遂亮為蘇定方此次滅國之戰撰寫了《大唐平百濟國碑銘》。其全文被刻于高五尺二寸，寬四丈六尺二寸的紀功碑上，此碑後被樹立于泅比城內的定林寺石塔上。隨後蘇定方攜百濟第三十一代國王扶餘義慈及太子隆、泰等五十八人回師洛陽，百濟國的疆域則被納入唐朝版圖，分別設置了熊津、馬韓、東明、金連和德安五個都督府，下轄三十七州，二百五十縣。左驍衛郎將劉仁願受命率領萬名唐軍與新羅王子金仁泰所率的七千新羅軍，共同守衛百濟府城。十一月一日，蘇定方于則天門獻俘，朝廷為此「賜天下大酺三日」。蘇定方則被升為左武衛大將軍，並加授其子蘇慶節為尚輦奉御。

征高句麗

顯慶六年十二月月十六日，唐高宗李治打算御駕親征，詔以契苾何力為浿江道行軍大總管，蘇定方為遼東道行軍大總管，劉伯英為平壤道行軍大總管，程名振為鏤方道總管，率兵分道進擊高句麗。後因武后勸阻，唐高宗取消御駕親征念頭。

龍朔元年（661年）五月，唐軍的作戰部署發生了較大的變化，以任雅相為浿江道行軍總管，契苾何力為遼東道行軍總管，蘇定方為平壤道行軍總管，與蕭嗣業及諸胡兵凡三十五軍，水陸分道並進。八月，蘇定方在浿江（今朝鮮大同江）擊敗高句麗軍並拿下了馬邑山。唐軍紮營于馬邑山上，繼續進軍包圍了平壤城（高句麗首都）。北線的陸路唐軍進展卻相對緩慢，高句麗權臣蓋蘇文遣其長子泉男生率精兵數萬，固守鴨綠江，唐軍無法渡江，雙方一直殭持到九月底。天氣開始寒冷，鴨綠江水結成堅冰，唐軍在契苾何力的率領下踏冰而過，鼓譟奮擊，高句麗軍大潰，唐軍追擊數十里，斬首三萬級，其餘部眾全都投降，只有泉男生逃了回去。正當遼東道行軍大總管契苾何力率領的北路唐軍順利推進，將南下與蘇定方會師平壤的時候，唐高宗下詔班師，于是撤軍，很快漠北鐵勒九姓發生了叛亂，回紇比粟毒與同羅、僕固進犯大唐邊境。十月十一日，蕭嗣業回國改任仙萼道行軍總管並加入鐵勒平叛大軍。兩人班師後，唐軍南北合擊高句麗的戰略部署落空，戰爭陷入了持久戰。

龍朔二年（662年）初，沃沮道總管，蠻酋龐孝泰率嶺南兵戰于蛇水之上，「賊知其懦，襲破之」，與其子十三人皆戰死。同月，浿江道行軍大總管任雅相在軍中病逝。孤軍圍城的蘇定方沒有辦法得到友軍的協同作戰援助，又正逢大雪，攻克平壤已不可能，遂解除包圍，于二月班師回國。

晚年

龍朔三年（663年），吐谷渾被吐蕃祿東贊所破，蘇定方奉命任涼州安集大使節度諸軍，鄭仁泰、獨孤卿雲、辛文陵等，負責對吐蕃的守備。此外18世紀中葉成書的《如意寶樹》就予以引用說：「芒松贊時期與漢人交戰,漢兵來藏時,大臣噶爾(祿東贊)戰死疆場, 布達拉宮被燒毀。」但從敦煌遺書、《西藏王臣記》和《新紅史》的記載可看出，670年唐蕃雙方在大非川交戰前幾年便爆發了衝突

乾封二年（667年），蘇定方病死，終年七十六歲。高宗在最初時尚不知情，等從他處聽說了蘇定方逝世的消息後，頗為悲傷痛惜，責備侍臣道：「蘇定方對國家有功，按例應當褒獎封贈，卿等不說，致使死後榮寵未能及時頒下。言及于此，不禁哀傷悲嘆。」于是立即下詔，追贈蘇定方為左驍衛大將軍、幽州都督，謚號「莊」。

歷代評價

• 《舊唐書》：「邢國公神略翕張，雄謀戡定，輔平屯難，始終成業。疏封陟位，未暢茂典，蓋闕如也。」

贊曰：「五將雄雄，具立邊功。張、蘇二族，功名始終。郭、薛、務挺，徼功奮命。垂則窮邊，兵無常勝。」

• 《新唐書》：「唐所以能威振夷荒、斥大封域者，亦有虎臣為之牙距也。至師行數千萬里，窮討殊斗，獵取其國由鹿豕然，可謂選值其才歟！

• 李綱：「李大亮宿衛之忠，裴行儉、蘇定方術略之奇，秦叔寶、薛仁貴、李嗣業搏戰之勇，高崇文紀律之嚴，王忠嗣執守之固，李抱真訓練之精，張萬福樂善之篤，李光顏、愬謀慮之決，皆凜然有賢將之風

• 愛新覺羅·載湉：「自古大一統之世。必為億萬年之圖。西逾蔥嶺。漢通鑿空之官。北界金山。唐設北庭之府。輪台屯戍。外輯烏孫金滿建城。遠收伊列。凡茲經略。能略言歟。蘇定方之討沙缽羅。速不台之窮默爾奇。此其功烈。

• 魏元忠：臣聞帝王之道，務崇經略；經略之術，必仗英奇。自國家良將，可得言矣。李靖破突厥，侯君集滅高昌，蘇定方開西域，李勣平遼東，雖奉國威靈，亦其才力所致。古語有之：『人無常俗，政有理亂，兵無強弱，將有能否』。由此觀之，安邊境，立功名，在于良將也。

• 杜祐：國朝李靖平突厥，李勣滅高麗，侯君集覆高昌，蘇定方夷百濟，李敬玄、王孝傑、婁師德、劉審禮皆是卿相，率兵御戎，戎平師還，並無久鎮

• 黃道周：蘇子定方，少年驍勇。鄉里賊侵，賴之不恐。突厥從征，乘霧一湧。誅者不勝，降者接踵。賀魯再征，攢槊殊猛。大雪不休，砍幾絕種。後襲諸敵，三路雲擁。面縛而降，獻俘丹甬。論法應誅，苦求恩寵。蔥嶺以西，因而朝拱。」

• 陳元靚：「邢公禦侮，闞如虓虎。生執都曼，鉗驅賀魯。暨平百濟，凡攻皆取。伐國之功，焜耀千古。

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