Early life and rise to power

Xiǎobái was born as one of Duke Xi of Qi's sons, though not in line of succession for the throne as he had at least two older brothers: Zhu'er and Jiu. In his youth, Xiǎobái was tutored by Bao Shuya. When Duke Xi eventually died, Zhu'er became Qi's next ruler as "Duke Xiang" but his reign was fraught with internal conflicts and scandals. Recognizing this and fearing for his pupil's life, Bao Shuya took Xiǎobái and fled with him to the state of Ju where they went on to live in exile.

Duke Xiang was assassinated in 686 BC, which allowed his cousin, Wuzhi, to ascend the throne. After just one month in office, however, Wuzhi was also murdered. With these two dead, Xiǎobái returned to Qi with the goal of becoming the next duke. He faced opposition in the form of his older brother Jiu however. Prince Jiu, by then also in exile, managed to gain the support of several high-ranking officials in Qi, his tutor Guan Zhong and Duke Zhuang of Lu. Before Jiu could be installed as new duke of Qi, however, Xiǎobái managed to seize control of Qi's government as well as its army, and was crowned as "Duke Huan of Qi" in 685 BC. The army of Lu under Duke Zhuang promptly invaded in order to install Prince Jiu on the throne, but the invading force suffered a crushing defeat at Ganshi and had to retreat. Qi's army under Bao Shuya in turn invaded Lu, and demanded Jiu and his supporters be handed over. To appease Duke Huan, Duke Zhuang then executed the rogue prince and delivered Guan Zhong to Qi as a prisoner.

Reign

Rise to hegemon

Though he was now secure on the throne, the question that remained for Duke Huan was what to do with Guan Zhong who had so prominently supported his rival brother. Bao Shuya asked his newly crowned ruler to not just spare Guan Zhong, but to even employ him as chief minister due to his great talents. Duke Huan followed this advice, and Guan Zhong became his most important and capable advisor. The two went on to reorganize Qi's government and society, dividing both the land as well as the people into regulated units and enforcing a meritocratic system of governance. This greatly strengthened Qi, as it allowed the state to "mobilize human and material resources more effectively than other Zhou states, which remained loosely structured." As Qi had already been a powerful polity in a favorable strategic situation before, these reforms managed to bring Qi to "an unprecedented status of leadership in the entire Zhou world". Together, Duke Huan and Guan Zhong worked toward achieving dominance over the other Zhou states, and as time went on ever more of them became followers of Qi.

Hegemony

Eventually Duke Huan invited the rulers of Lu, Song, Chen, and Zheng to a conference in 667 BC, where they elected him as their leader. After hearing of this, King Hui of Zhou appointed Duke Huan hegemon (ba) with the authority to operate militarily in the name of the royal court. Duke Huan and Guan Zhong envisioned the office of "hegemon" not just as mere position of military power, but rather as one that was supposed to "restore the authority of the Son of Heaven" or, more practically, restabilize the old realm of the Zhou dynasty under the leadership of Qi.

Consequently, Duke Huan intervened in matters that concerned the interstate relationships of the Zhou polities, both on behalf of King Hui as well as to assert his own position as hegemon. Such interventions included a punitive expedition against Wey in 671 BC, because this state had defied King Hui, as well as involvement in a power struggle in Lu in order to cement Qi's power. Another major concern for Duke Huan was the threat that outside powers (derogatorily called the "Four Barbarians") posed to the Zhou states, and he would launch numerous campaigns to fend off these "barbarians". Most notably, he saved the states of Yan, Xing and Wey from invasions by non-Zhou groups, and tried to stop the expansion of Chu in the south. In 656 BC he led an alliance of eight states against a satellite state of Chu, Cai, and defeated it. The alliance then proceeded to invade Chu itself, and eventually a pact was concluded. Chu stopped its northward expansion and agreed to take part in an compulsory interstate meeting at Shaoling. This meeting, the first of its kind, set a precedent.

Over the following years, Duke Huan convened numerous interstate meetings under the auspices of the Zhou royal family. Points of discussion during these meetings ranged from military matters to economics to general orders concerning governance and laws. Overall, the ruler of Qi managed to restore some stability in the volatile and fractious Zhou realm. Historian Cho-yun Hsu summarizes that Duke Huan "used his Ba hegemon leadership to set up a new order for an interstate community that was to be guarded by consensus rather than authority."

Decline in power and death

After almost forty years on the throne, however, Duke Huan's dominance began to gradually decline. His efforts to completely stop Chu's expansion failed, as the southern state had simply shifted its attention from the north to the east. There, along the Huai River, Chu conquered or invaded several states allied with Qi. The last major anti-Chu military alliance assembled by Duke Huan failed to stop this development, and was even defeated during the Battle of Loulin in 645 BC. Guan Zhong also died in that year, depriving the ruler of Qi of his most important advisor. Having grown ill, Duke Huan was increasingly ignored by the leaders of other states, and even his authority over Qi itself declined as various political factions began to vie for power.

These factions were formed by high officials as well as six of the duke's sons. These six, namely Zhao, Wukui, Pan, Shangren, Yuan, and Yong, were all the children of different concubines, as Duke Huan's three main wives bore him no sons. As a result, all of them felt themselves entitled to the throne. Though Qi's ruler had designated Prince Zhao as his heir and even charged Duke Xiang of Song with ensuring that he would ascend the throne, this did not stop the other five from plotting their own rise to power. According to the Guanzi, the elderly duke had also to deal with four powerful officials: Tang Wu, the court sorcerer; Yiya, the chief cook; Shu Diao, the chief of the eunuchs; and Gongzi Kaifang, a leading courtier. Shortly before his death, Guan Zhong had advised that they should be sent into exile. Duke Huan did so, but he found himself missing their particular talents at the court and allowed them to return. They then conspired against him, and locked him in his room, secretly starving him to death. Other notable sources for these events, such as the Zuo Zhuan and the Records of the Grand Historian do not mention this purported assassination.

Duke Huan of Qi finally died in late 643 BC, and the capital Linzi quickly descended into violence. His six sons, supported by various officials, took up arms against each other in order to size the throne, starting a war of succession. In this chaos, Duke Huan could not be buried and his corpse was left unattended in his bedchamber for between seven days and three months. By the time he was finally encoffined, the corpse had begun to rot. With Duke Huan's sons fighting for the throne, Qi was severely weakened and lost its status as China's predominant state. Although Zhao, by then ruling as Duke Xiao of Qi, eventually attempted to regain his father's hegemony, he failed and Duke Wen of Jin became the next hegemon.

Family

Wives:

• Wang Ji, of the Ji clan of Zhou (王姬 姬姓), a princess of Zhou by birth

• Xu Ying, of the Ying clan of Xu (徐嬴 嬴姓)

• Cai Ji, of the Ji clan of Cai (蔡姬 姬姓)

Concubines:

• Wey Gong Ji, of the Ji clan of Wey (衛共姬 姬姓), the mother of Prince Wukui

• Shao Wey Ji, of the Ji clan of Wey (少衛姬 姬姓), the mother of Prince Yuan

• Zheng Ji, of the Ji clan of Zheng (鄭姬 姬姓), the mother of Crown Prince Zhao

• Ge Ying, of the Ying clan of Ge (葛嬴 嬴姓), the mother of Prince Pan

• Mi Ji, of the Ji clan of Mi (密姬 姬姓), the mother of Prince Shangren

• Song Hua Zi, of the Zi clan of Song (宋華子 子姓), the mother of Prince Yong

Sons:

• Prince Wukui (公子無虧; d. 642 BC), ruled as the Duke of Qi in 642 BC

• Prince Yuan (公子元; d. 599 BC), ruled as Duke Hui of Qi from 608–599 BC

• Crown Prince Zhao (太子昭; d. 633 BC), ruled as Duke Xiao of Qi from 641–633 BC

• Prince Pan (公子潘; d. 613 BC), ruled as Duke Zhao of Qi from 632–613 BC

• Prince Shangren (公子商人; d. 609 BC), ruled as Duke Yì of Qi from 612–609 BC

• Prince Yong (公子雍)

　• Granted the fiefdom of Gu (谷) in 634 BC

• Seven sons who served as Grand Masters (大夫) of Chu

Daughters:

• Qi Jiang (齊姜)

　• Married Duke Wu of Jin (d. 677 BC)

　• Married Duke Xian of Jin (d. 651 BC), and had issue (Crown Prince Shensheng, Mu Ji (the wife of Duke Mu of Qin and mother of Duke Kang of Qin))

Ancestry

生平

與兄長爭位

齊襄公晚年時，齊國國政混亂。公子糾的師傅管仲與公子小白的師傅鮑叔牙雙雙都預感齊國將發生大亂，就各自保護兩位公子到魯國與莒國。

齊襄公十二年（前686年），齊大夫連稱、管至父謀殺齊襄公，立其堂弟公孫無知(齊僖公同母弟夷仲年之遺腹子)為君。

齊桓公元年 （前685年），齊大夫雍廩殺公孫無知，與大夫國氏、高傒等秘密迎回人在莒國的公子小白回到臨淄（山東淄博東）即位，為齊桓公。

魯國聽說公孫無知被殺，也派兵送小白的哥哥公子糾回齊國，而管仲帶兵堵截住莒國到齊國的路。傳說管仲一箭射中小白帶鉤，小白咬舌吐血假裝倒地而死，管仲派人回魯國報捷。魯國于是就慢慢地送公子糾回國，六日方抵。而這時小白已兼程趕回齊國，高傒立其為國君，是為桓公。

即位首戰於魯

小白趕回即位後，隨即發兵迎擊魯國，在乾時（今山東省桓台縣）大戰，魯軍敗走。

小白要殺管仲，鮑叔牙勸說：「臣幸運地跟從了君上，君上現在成為了國君。如果君上只想讓齊國成為強國，那麼有叔牙和高傒就夠了。如果君上想成就天下霸業，那麼非管仲不可。管仲到哪個國家，哪個國家就能強盛，不可以失去他。」桓公聽從鮑叔牙的建議，騙魯國說，要親自殺死管仲，鮑叔牙給魯侯寫了一封信，信中說：「公子糾是齊君的兄弟，不忍殺他，請魯國殺他。公子糾的老師召忽、管仲是仇人，請魯國把他們送來剁成肉泥；如不從命，將要出兵討伐魯國。」

魯人害怕，殺公子糾，召忽自殺，管仲被囚禁。

齊公姜小白和管仲談論霸王之術，大喜過望，以其為大夫，委以政事。

管仲相齊

齊桓公起用管仲進行改革，建立宮廷官制。在相之下，設立大司行、大司田、大司馬、大司理、大諫之官等五官，分別掌管外交、經濟、軍事、刑法、監察等，削弱了世卿的統治權力，增強了君主集權，形成了完整的中央政權機構。並構建地方行政機構，實行國野分治的方法，國都為國，其他地方為野。國中設二十一鄉，其中工商六鄉，士十五鄉。每五家為一軌，軌設軌長。每十軌為一里，里設里司。每四里為一連，連設連長。每十連為一鄉，鄉設良人。再為臣設三卿，工設三族，商設三鄉，澤設三虞，山設三衡，加強管理。對于野，以三十家為一邑，邑設邑司。十邑為一卒，卒設卒帥。十卒為一鄉，鄉設鄉帥。三鄉為一縣，縣設縣帥。十縣為一屬，屬設大夫。全國共有五屬，設五屬大夫分別治理。並劃分各級官員的職權範圍，屬大夫管刑獄，縣帥管劃分田界，鄉帥管一般政事，要求他們兢兢業業，不許荒廢政事，不然處以刑罰。每年正月，五屬大夫要向桓公匯報述職，桓公根據政績來進行獎懲。加上實行軍政合一、兵民合一的的制度。規定士鄉的居民必須服兵役。每家出一人為士卒，每軌為一伍，伍由軌長率領。每里五十人為一小戎，小戎由里司率領。每連二百人為卒，卒由連長率領。每鄉兩千人為一旅，旅由良人率領。五鄉一萬人為一軍，十五鄉共三軍，桓公、國子、高子各率一軍。農閒時訓練，有戰事時出征。這樣既提高了士兵戰鬥力，也不必支付養兵的費用。另外，為解決武器不足的問題，規定犯罪可以用兵器贖罪。犯重罪可以用甲和戟贖罪，犯輕罪的可以用盾和戟贖罪，犯小罪可以用金屬贖罪，銅用來鑄兵器，鐵用來鑄農具。訴訟成功則要交一束箭。從此，齊國的兵器也漸漸充足起來。亦通過減少稅收，增加人口的生育水平。從而提高齊國的總體人口數量。對商業特別是鹽商加以重稅，以補足稅收的差異。並實行了糧食「平準」的政策，避免富人搶奪窮人的糧食，進一步限制貧富的差距。也間接承認了農民自由買賣糧食的權利及自由私田的合法性，並且還保障了私田農的生產利潤。這種經濟政策，亦為經濟層面的國君集權。並在齊國各處設立「女閭」，將戰犯或罪犯的寡婦充于其間，並抽以稅收。這樣的做法導致了許多秦人，晉人慕名而來到齊國大大的充實了齊國的國庫。

與魯國紛爭再起

齊桓公二年（前684年），在長勺被魯國擊敗。

齊桓公五年（前681年），攻打魯國，魯國戰敗，魯莊公請求割遂邑求和，桓公答應了，與魯國在柯會盟。但魯國力士曹沫卻用匕首在壇上劫持桓公，說：「歸還侵占魯國的土地！」桓公答應他。在曹沫拿掉匕首後，桓公後悔，想不給魯國土地並殺曹沫。管仲勸阻說：「不可喪失天下諸侯的信任。」于是就歸還了魯國土地。

九合諸侯

齊桓公七年（前679年），在甄召集宋國、陳國、蔡國、邾國四國諸侯會盟，齊桓公是歷史上第一個充當盟主的諸侯。後宋國違背盟約，齊桓公以周天子的名義，率幾國諸侯伐宋，迫使宋國求和，此即為「九合諸侯」的第一次。另外，齊桓公還滅了譚國、遂國、鄣國等小國。

田氏入齊

齊桓公十四年（前672年），陳厲公子完，即田完，逃到齊國，桓公想任命他為卿，他不接受，桓公就任命他為工正。這間接造成其後人奪去了姜姓齊國的政權，即田氏代齊。

救燕國伐山戎

齊桓公二十三年（前663年），山戎攻打燕國，燕向齊求救。齊桓公救燕，攻打山戎，一直打到孤竹國才停。

燕莊公送齊桓公到齊境。齊桓公說：「不是天子，諸侯向送不能出境，我不可以對燕無禮。」

于是把燕君所到的地方割給了燕國，叮囑燕君學習召公為政，像周成王周康王時一樣給周朝納貢。

諸侯聽說此事，都擁護齊國。

救邢國伐北狄|狄

齊桓公二十五年（前661年），狄人攻打邢國，桓公出兵救援，扶立在齊國的衛國公子毀，是為衛文公。

殺妹哀姜（魯閔公之母姐）

齊桓公二十七年（前659年），桓公妹妹哀姜是魯閔公的姨母，她和魯公子慶父淫亂。慶父弒閔公，哀姜想立慶父，而魯人立僖公。桓公召回哀姜，將其殺死。

救衞國伐北狄|狄

齊桓公二十八年（前658年），衞文公被狄人騷擾，向齊求救。齊打敗狄人，並為衞國築楚丘城，把衞國臣民遷到那裡。

因蔡姬晃船而伐蔡國

齊桓公二十九年（前657年），桓公和蔡姬在水中遊玩，蔡姬晃船，桓公心怕，阻止蔡姬。蔡姬不聽，晃個不停。齊桓公出船，大發雷霆，把蔡姬送了回去。蔡國也不高興，把蔡姬又嫁到楚國。齊桓公發怒，興兵討伐。

齊桓公三十年春（前656年），齊桓公帶領魯、宋、陳、衞、鄭、許、曹七國諸侯伐蔡，蔡國臣民反叛。

藉楚國沒有進貢而討伐楚國

楚成王十六年（前656年），齊桓公因為蔡姬之恨侵楚，楚成王起兵迎戰，問：「為什麼來到我國？」。

管仲找了一些理由，回答說：「從前召康公對我國先君太公說：『你要討伐諸侯，輔助周室。』給我們先君東到大海，西到黃河，南到穆陵，北到無棣的土地。楚國沒有進貢苞茅，使周王祭祀時沒有用來縮酒的東西。周昭王南征沒有回來。是因為這些來責問。」

楚成王說：「沒有進貢，實有此事，這是寡人的過錯。昭王南征沒有回來，你到漢水岸邊去問吧。」

聯軍推進至陘。夏，成王派屈完帶兵抵禦，聯軍退回召陵。屈完前往召陵向齊桓公請求講和，齊桓公同意。

齊桓公和屈完檢閱部隊時，對自己所率領的聯軍赫赫軍容感到非常驕傲。而屈完在此時勸解桓公「以德綏諸侯」。于是參與聯軍的諸侯們和屈完舉行盟誓後退兵。

周惠王崩

齊桓公三十三年（前653年）冬，惠王崩。周襄王怕異母弟王子帶爭王位，因此不發喪，向齊國告難。直到大局已定才公佈周惠王死訊。

再會諸侯

齊桓公三十五年（前651年）夏，桓公大會諸侯于葵丘（今河南民權）。周襄王派宰孔賜桓公文武胙，彤弓矢，大輅（諸侯朝服之車），並免去了桓公下拜。

齊桓公於是不拜，管仲說：「不可。」，于是齊桓公還是下拜收賜。

齊桓公三十五年（前651年）秋，又和諸侯會于葵丘，周派宰孔參加。齊桓公越來越驕傲，諸侯有不少背叛的。宰孔對晉侯說：「齊桓公太驕傲了。」這年，晉獻公死，晉國發生內亂，秦穆公立公子夷吾為晉君，桓公也出兵平亂。這時周室式微，只有齊、晉、楚、秦強大。晉國內亂，秦國偏遠，楚王以蠻夷自居，齊桓公成為中原的霸主。

齊桓公說：「寡人向南打到召陵，望見熊山。北伐山戎、離枝、孤竹。西伐大夏，深入流沙之中。登上太行山，到卑耳山才返回。諸侯不要違背寡人。我三次聯合諸侯出兵，六次和諸侯會盟，定襄王太子之位。說以前三王偉大，現在我和他們有什麼兩樣嗎？我想在泰山封禪。」管仲勸說，桓公不聽。管仲又說，要得到遠方的珍奇怪物才能封禪，桓公才不考慮這事。

晚年

易牙以廚藝服侍齊桓公。齊桓公說：「只有蒸嬰兒肉還沒嘗過。」於是易牙將其長子蒸了獻給齊桓公吃。

齊桓公四十一年（前645年），管仲重病，桓公問他：「群臣中誰可以代你為相？」管仲說：「了解臣下沒有人比得上君主。」桓公說：「易牙如何？」管仲回答：「殺掉孩子來討好君主，不合人情，不可以。」 桓公說：「開方如何？」管仲回答：「背棄親人來討好君主，不合人情，難以親近。」 桓公說：「豎刁如何？」管仲回答：「自己閹割來討好君主，不合人情，難以親愛。」管仲死後，齊桓公不聽管仲的話，重用三人，三人專權。

齊桓公四十二年（前644年），戎攻打周朝，周告急於齊，齊令各國諸侯發兵救周。

齊桓公四十三年（前643年），齊桓公重病，五公子（公子無虧、公子昭、公子潘、公子元、公子商人）各率黨羽爭位。易牙、豎刁把桓公軟禁到寢宮裡，宮外築上高牆，不許任何人見他。一個宮女翻牆到了桓公身邊。桓公問她有沒有食物和水，宮女無可奈何。桓公長嘆：「嗟呼！聖人所見豈不遠哉！若死者有知，我將何面目見仲父乎？」這個宮女在《東周列國志》稱作晏娥。

冬十月七日，齊桓公病死，五公子互相攻打，齊國一片混亂，桓公尸體在床上放了六十七天，尸蟲都從尸體上爬了出來，「身死不葬，蟲流出戶」。十二月十四日，新立的齊君無虧才把桓公收殮。

故事

遺冠雪恥

《韓非子·難二》齊桓公飲酒醉，遺其冠，恥之，三日不朝。管仲曰：「此有國之恥也，公胡其不雪之以政？」公曰：「胡其善！」因發倉囷賜貧窮，論囹圄出薄罪。處三日而民歌之曰：「公胡不複遺冠乎！」—— 或曰：管仲雪桓公之恥于小人，而生桓公之恥于君子矣。使桓公發倉囷而賜貧窮，論囹圄而出薄罪，非義也，不可以雪恥；使之而義也，桓公宿義，須遺冠而後行之，則是桓公行義非為遺冠也？是雖雪遺冠之恥于小人，而亦生遺義之恥于君子矣。且夫發囷倉而賜貧窮者，是賞無功也；論囹圄而出薄罪者，是不誅過也。夫賞無功，則民偷幸而望于上；不誅過，則民不懲而易為非。此亂之本也，安可以雪恥哉？

五顧布衣

微服出巡

索人勞，使人佚。

三難

家庭

齊桓公在位四十三年去世，當年是魯僖公十七年（前643年），《左傳》于當年介紹了齊桓公的配偶和兒子的情況。

配偶

• 嫡妻：王姬，膝下無子。

• 嫡妻：徐嬴，膝下無子。

• 嫡妻：蔡姬，膝下無子。

• 妾：長衛姬，生公子無虧（武孟）。

• 妾：少衛姬，生齊惠公元。

• 妾：鄭姬，生齊孝公昭，他是桓公生前立的太子。

• 妾：葛嬴，生齊昭公潘。

• 妾：密姬，生齊懿公商人。

• 妾：宋華子，生公子雍。

• 公子糾遺孀。

子女

• 公子無虧（武孟），長衛姬所生。公子無虧于齊桓公死後的前643年被立為齊侯。

• 齊惠公元，少衛姬所生。于前608年至前599年在位。

• 齊孝公昭，鄭姬所生。桓公生前立的太子，于前642年至前633年在位。

• 齊昭公潘；葛嬴所生。于前632年到前613年在位。

• 齊懿公商人；密姬所生。于前612前609年在位。

• 公子雍，宋華子所生。

• 齊姜，晉獻公夫人，為晉太子申生、秦穆公夫人穆姬的生母，秦康公的祖母。

齊桓公的諸子共統治齊國四十餘年。桓公之子不止以上說的六人，《左傳·僖公二十六年》記載，齊桓公有七個兒子去楚國做了大夫。

其他後裔

• 桓氏：以桓公謚號為氏，後裔如東漢桓榮。

• 東郭氏：齊莊公時有東郭偃及其姊東郭姜。東郭姜嫁予同為姜姓的齊丁公後裔崔杼，生子崔明。崔明後來是南北朝及唐代著名大族清河崔氏、博陵崔氏的祖先。

評價

《春秋公羊傳》之評價

《春秋公羊傳》說：「南夷北狄交，中國不絕如線，桓公攘夷狄而救中國。」齊桓公作為春秋時代的第一位霸主，他一向是被高度評價的。當時在夷狄的逼迫之下，中原各國的確遭到了極大的威脅，而通過改革而強盛起來的齊桓公，此時充當起了中原各國的保護神，打出了「尊王壤夷」的旗號。作為霸主，齊桓公又是會盟諸侯，又是插手別國事務，又是安定王室，又是征伐夷狄，可謂風光一時。

《春秋穀梁傳》之評價

穀梁傳譴責了齊桓公通過殺公子糾成為齊國國君的手段。。對于桓公前681年在北杏的會盟，《穀梁傳》認為齊桓公並不是周天子任命的方伯，如此是不應當的。。但在記載前667年桓公與諸侯在幽的會盟時，稱讚桓公仁義守信。對于桓公在前666年伐衛一事，《穀梁傳》認為桓公雖然是奉王命，但攻伐別國又索取財物，需要輕視。。《穀梁傳》認為桓公為燕國討伐山戎一事是莫大之善舉，需要稱讚。《穀梁傳》以為桓公駐曹救邢一事是害怕狄人，不值得讚揚，所以《春秋》避諱不書齊桓公。前658年桓公為衛國築楚丘城，對于此事《穀梁傳》認為桓公雖然有仁愛之心，但此舉超出禮制。桓公率大軍伐蔡，《穀梁傳》認為合乎正道。前655年桓公盟諸侯，擁戴周王的太子，《穀梁傳》認為這是變通禮制擁戴周王的做法值得肯定。《穀梁傳》對桓公在葵丘大會諸侯申明周王禁令表示稱讚。《穀梁傳》譴責桓公滅項一事，但又說桓公曾有存亡繼絕之功，所以為之避諱。對于桓公的去世，《穀梁傳》說此人不正道，但前文有所貶抑，記載他的去世時對他的尊敬。

《春秋左氏傳》之評價

關于齊桓公伐楚的「召陵之師」，也許首當其衝的楚國人最了解當時的情況。召陵之師過去一百多年後，楚國的大夫椒舉向追求霸業的楚靈王提到歷史上夏啟王、商湯王、周武王、周成王、周康王、周穆王、齊桓公和晉文公這「六王二公」之功業。而楚靈王在這些歷史人物的偉大業績中，僅選擇了齊桓「召陵之師」作為自己效仿的對象。可見楚國人心目中「召陵之師」是多麼雄壯。童書業推測各國當時兵力，認為「召陵之師」聯軍有多達一千數百乘兵車的兵力，在當時是前所未有的巨大兵力。在聯軍深入楚境的強壓下，楚國被迫放棄在戰場上擊敗聯軍的努力，而是乞求加入齊國同盟，此事在楚人心中印象極深。而齊桓去世後的前641年想謀求霸權的楚國在齊國參加盟會，仍然以齊國為盟主。可見齊桓霸業之盛。

有人認為，當時齊桓公並未有多少實力，當時秦晉都還不是很強大，而對于楚國，齊桓公不過是定了一個盟約，並沒有試試楚國「方城以為城，漢水以為池」的雄厚實力。至于抗擊夷狄，更多的是打敗了實力不強的狄人，而對于楚國出兵滅了一些小國的行為，齊桓公並沒有幹涉。

其他評價

孔子認為齊桓公個性正直而不狡詐，與晉文公狡詐又不正直的個性相反。孔子與子路、子貢談話時，子路與子貢批評管仲曾侍奉公子糾而不能死節，孔子舉管仲輔佐桓公會合諸侯、一匡天下的事蹟做為回應。

孟子批評齊桓公，認為他不過是靠霸道，而不是王道。孟子認為孔子的弟子不會稱讚齊桓公、晉文公的事蹟。然而孔子曾大力稱道管仲佐齊桓公稱霸，認為這是「民到于今受其賜」的盛舉，並賦予佐桓公稱霸的管仲「如其仁！如其仁！」的美譽。

齊桓公生活糜爛，《史記》：「桓公好內，多內寵，如夫人（妾）者六人」、「桓公病，五公子各樹黨爭立。」如此多的兒子也為以後的內亂埋下了隱患。不僅如此，齊桓公在近親性關係上也很混亂，「寡人有污行，不幸而好色，姑姊有不嫁者」 ，「齊桓公好婦人之色，妻姑姊妹，而國中多淫于骨肉。」另外齊桓公親近小人，甚至吃人肉。