Guo Jia () (170– October 207), courtesy name Fengxiao, was a military adviser to the warlord Cao Cao during the late Eastern Han dynasty of China. Throughout his 11 years of service, Guo Jia aided Cao Cao greatly with his brilliance and foresight, and his strategies were instrumental to Cao Cao's triumphs over rival warlords such as Lü Bu and Yuan Shao. For example, four years before Cao Cao's decisive victory over Yuan Shao at the Battle of Guandu, Guo Jia already foresaw that Cao Cao would win when he pointed out ten advantages Cao Cao had over Yuan Shao.
Historical sources on Guo Jia's life The authoritative historical source on Guo Jia's life is the Records of the Three Kingdoms (Sanguozhi), which was written by Chen Shou in the third century. In the fifth century, Pei Songzhi annotated the Sanguozhi by incorporating information from other sources to Chen Shou's original work and adding his personal commentary. Some alternative texts used in the annotations to Guo Jia's biography include: Fu Zi, by Fu Xuan; Wei Shu (Book of Wei), by Wang Chen, Xun Yi and Ruan Ji; Shiyu (Accounts of this Generation), by Guo Song.
Early life Guo Jia was from Yangzhai County (), Yingchuan Commandery (), which is in present-day Yuzhou, Henan.(郭嘉字奉孝，潁川陽翟人也。) Sanguozhi vol. 14. As a youth, he was famous for his intelligence and foresight. Since reaching adulthood at around the age of 19, Guo Jia had been travelling around the country and befriending members of the scholar-gentry and other talented persons. He did not associate himself with the hoi polloi and was thus not very well known outside of his circles. However, all those who knew him recognised his talent and felt that he was extraordinary. When he was 26, he served in the Han government as a minor official in the office of the Minister over the Masses ().(傅子曰：嘉少有遠量。漢末天下將亂。自弱冠匿名迹，密交結英儁，不與俗接，故時人多莫知，惟識達者奇之。年二十七，辟司徒府。) Fu Zi annotation in Sanguozhi vol. 14.
Guo Jia once travelled to Hebei to meet Yuan Shao, an influential warlord who controlled most of northern China at the time. He later told Yuan Shao's advisers Xin Ping and Guo Tu, "An intelligent adviser should be prudent when he chooses which lord he wishes to serve so that his lord will heed every piece of advice he gives. The adviser can then establish his reputation. Lord Yuan (Yuan Shao) wishes to mimic the Duke of Zhou by recruiting men of talent to serve under him but he does not know how to tap into their abilities. He focuses too much on unnecessary details and neglects the main points; he likes to listen to many ideas but is indecisive. It is difficult for him to save the Empire from its troubles and achieve hegemony over the various warlords!" Guo Jia then left Yuan Shao.(初，北見袁紹，謂紹謀臣辛評、郭圖曰：「夫智者審於量主，故百舉百全而功名可立也。袁公徒欲效周公之下士，而未知用人之機。多端寡要，好謀無決，欲與共濟天下大難，定霸王之業，難矣！」於是遂去之。) Sanguozhi vol. 14.
Coming to serve Cao Cao Around the time, Cao Cao had a brilliant adviser, Xi Zhicai (), whom he appreciated greatly, but Xi died early. Cao Cao told another adviser Xun Yu, "Ever since Xi Zhicai died, I've been lacking someone whom I can form strategies with. I heard there are many talents in the Ru and Ying regions. Who can replace Xi Zhicai?" Xun Yu recommended Guo Jia to Cao Cao. Cao Cao and Guo Jia had a discussion on the affairs of their time, after which the former remarked: "This must be the man who will help me achieve greatness." Guo Jia also happily said, "He's truly the lord I wish to serve." Guo Jia was then appointed as a Libationer () in the army of Cao Cao, who then held the position of Minister over the Masses () in the Han imperial court.(先是時，潁川戲志才，籌畫士也，太祖甚器之。早卒。太祖與荀彧書曰：「自志才亡後，莫可與計事者。汝、潁固多奇士，誰可以繼之？」彧薦嘉。召見，論天下事。太祖曰：「使孤成大業者，必此人也。」嘉出，亦喜曰：「真吾主也。」表為司空軍祭酒。) Sanguozhi vol. 14.
Evaluation of Cao Cao's advantages over Yuan Shao The Fu Zi recorded a detailed conversation between Guo Jia and Cao Cao, in which the former carefully pointed out ten advantages the latter had over Yuan Shao.(對曰：「劉、項之不敵，公所知也。漢祖唯智勝；項羽雖彊，終為所禽。嘉竊料之，紹有十敗，公有十勝，雖兵彊，無能為也。) Fu Zi annotation in Sanguozhi vol. 14. Cao Cao asked Guo Jia, "Benchu (Yuan Shao) rules Ji, Qing and Bing provinces and has vast territories and large numbers of troops under his command. However, he has also been making offensive moves. I intend to attack him, but my forces are weaker than his, so what should I do?"(傅子曰：太祖謂嘉曰：「本初擁冀州之衆，青、并從之，地廣兵彊，而數為不遜。吾欲討之，力不敵，如何？」) Fu Zi annotation in Sanguozhi vol. 14.
Guo Jia replied,
Cao Cao laughed and said, "If what you've said is true, I feel really flattered." Guo Jia said, "Yuan Shao is now occupied in a war with Gongsun Zan in the north. We should head east to attack Lü Bu. If we don't eliminate Lü Bu first, when Yuan Shao attacks us and Lü Bu assists him, we'll be in deep trouble." Cao Cao agreed with Guo Jia.(太祖笑曰：「如卿所言，孤何德以堪之也！」嘉又曰：「紹方北擊公孫瓚，可因其遠征，東取呂布。不先取布，若紹為寇，布為之援，此深害也。」太祖曰：「然。」) Fu Zi annotation in Sanguozhi vol. 14.
Cao Cao's campaign against Lü Bu
In 198, Cao Cao launched a campaign against his rival Lü Bu in Xu Province, leading to the Battle of Xiapi. Lü Bu lost three battles and retreated to Xiapi (下邳; present-day Pizhou, Jiangsu). Cao Cao's forces besieged the city for months but they still could not conquer it because Lü Bu and his men resisted firmly. By then, Cao Cao's troops were tired and weary of battle, so Cao intended to withdraw his forces. However, Guo Jia and Xun You told Cao Cao, "Lü Bu is courageous but foolhardy. His army's morale is low because he has already lost three battles. The troops look up to their commander. If their commander shows any sign of weakness, the men will lose their fighting spirit. Lü Bu may have Chen Gong as an intelligent adviser but the latter's strategies always come late. Now, we should take advantage of this situation, when the morale of Lü Bu's forces is low and when Chen Gong has yet to think of a solution, to press on a fierce attack and we'll achieve victory." Cao Cao heeded their advice and directed the waters of the Yi () and Si rivers to flood Xiapi, resulting in his triumph over Lü Bu.(征呂布，三戰破之，布退固守。時士卒疲倦，太祖欲引軍還，嘉說太祖急攻之，遂禽布。語在荀攸傳。) Sanguozhi vol. 14.(建安三年， ... 是歲，太祖自宛征呂布，至下邳，布敗退固守，攻之不拔，連戰，士卒疲，太祖欲還。攸與郭嘉說曰：「呂布勇而無謀，今三戰皆北，其銳氣衰矣。三軍以將為主，主衰則軍無奮意。夫陳宮有智而遲，今及布氣之未復，宮謀之未定，進急攻之，布可拔也。」乃引沂、泗灌城，城潰，生禽布。) Sanguozhi vol. 10.
The Fu Zi recorded another piece of advice Guo Jia gave to Cao Cao during the Battle of Xiapi: "In the past, Xiang Yu never lost any of the over 70 battles he fought in, but once the tide turned against him, he ended up in death and destruction. This was due to his reliance on his personal courage and his negligence towards strategy. Lü Bu has lost three consecutive battles and his army's morale is low and his defences are weakening. His might is not comparable to Xiang Yu, and he is now overwhelmed by defeat and weariness. If we take advantage of our successes to press on the attack on him, we can defeat him." Cao Cao agreed with him.(傅子曰：太祖欲引軍還，嘉曰：「昔項籍七十餘戰，未嘗敗北，一朝失勢而身死國亡者，恃勇無謀故也。今布每戰輒破，氣衰力盡，內外失守。布之威力不及項籍，而困敗過之，若乘勝攻之，此成禽也。」太祖曰：「善。」) Fu Zi annotation in Sanguozhi vol. 14.
Advice to Cao Cao on how to handle Liu Bei According to the Wei Shu, Guo Jia advised Cao Cao on how to handle Liu Bei when Liu Bei came to join Cao Cao in 196, after Lü Bu seized control of Xu Province from Liu's general Zhang Fei. On Cao Cao's suggestion, Emperor Xian appointed Liu Bei as the Governor () of Yu Province (). Someone told Cao Cao, "Liu Bei has the ambition of a hero. If you don't eliminate him now, he'll become a threat to you in the future." Cao Cao asked Guo Jia for his opinion, to which Guo replied, "That's true. However, when you raised an army in the name of righteousness and pledged to help the common people eliminate tyrants, you attracted talented and capable people to serve under you based on your sincerity and integrity. Liu Bei is known to be a hero, so if you kill him when he comes to serve you, you will be viewed as someone who harms men of virtue. Other talented persons will start to doubt you and may even change their minds about serving you. If that happens, who will help you achieve your goals? Therefore, it's imperative that you carefully consider the consequences of ruining your good reputation for the sake of eliminating one man who poses a threat to you." Cao Cao laughed and said, "I understand."(魏書曰：劉備來奔，以為豫州牧。或謂太祖曰：「備有英雄志，今不早圖，後必為患。」太祖以問嘉，嘉曰：「有是。然公提劒起義兵，為百姓除暴，推誠杖信以招俊桀，猶懼其未也。今備有英雄名，以窮歸己而害之，是以害賢為名，則智士將自疑，回心擇主，公誰與定天下？夫除一人之患，以沮四海之望，安危之機，不可不察！」太祖笑曰：「君得之矣。」) Wei Shu annotation in Sanguozhi vol. 14.
However, the Fu Zi gave a completely different account of Guo's advice to Cao Cao on how to handle Liu Bei. Guo Jia told Cao Cao, "Liu Bei has great ambitions and has won the hearts of many people. Zhang Fei and Guan Yu are formidable fighters and they have pledged to serve him with their lives. From what I observe, Liu Bei will never truly submit to anyone, and his intentions are unclear. The people in the past once said, 'If you let the enemy off today, they will become a threat to you for a long time.' You should settle (Liu Bei) soon." At the time, Cao Cao was using Emperor Xian as a figurehead to command respect and had attracted many heroes to serve under him so he did not heed Guo Jia's advice. When Cao Cao later sent Liu Bei with an army to attack Yuan Shu, Guo Jia and Cheng Yu warned Cao, "Liu Bei will rebel if you let him go!" By then, Liu Bei had already left and he really did rebel against Cao Cao as he later seized control of Xu Province from Che Zhou, the provincial governor appointed by Cao Cao. Cao Cao regretted not following Guo Jia's advice.(傅子曰：初，劉備來降，太祖以客禮待之，使為豫州牧。嘉言於太祖曰：「備有雄才而甚得衆心。張飛、關羽者，皆萬人之敵也，為之死用。嘉觀之，備終不為人下，其謀未可測也。古人有言：『一日縱敵，數世之患。』宜早為之所。」是時，太祖奉天子以號令天下，方招懷英雄以明大信，未得從嘉謀。會太祖使備要擊袁術，嘉與程昱俱駕而諫太祖曰：「放備，變作矣！」時備已去，遂舉兵以叛。太祖恨不用嘉之言。) Fu Zi annotation in Sanguozhi vol. 14.
Pei Songzhi noted that the Wei Shu account is exactly the opposite of the Fu Zi account, but did not give his opinion on which he regarded to be the genuine one.(案魏書所云，與傅子正反也。) Pei Songzhi's annotation in Sanguozhi vol. 14. The Chronicles of Huayang stated that following Lu Bu's defeat at Xiapi. Both Cheng Yu and Guo Jia encouraged Cao Cao to have Liu Bei killed but that Cao Cao refused fearing that such an act may hurt his reputation.(公謀臣程昱、郭嘉勸公殺先主。公慮失英豪望，不許。) Huayang Guo Zhi vol. 6.
Prediction of Sun Ce's death Between 194 and 199, the warlord Sun Ce embarked on a series of conquests in Jiangdong and seized control of most of the territories in the region. Around 200, Cao Cao finally engaged Yuan Shao at the Battle of Guandu. When Sun Ce heard that Cao Cao was locked in a stalemate with Yuan Shao at Guandu, he planned to lead an army across the Yangtze River and launch a surprise attack on the imperial capital Xu (許; present-day Xuchang, Henan), which was Cao Cao's base. When Cao Cao's men received news of the impending assault, they were all shocked and frightened, but Guo Jia said, "Sun Ce had newly conquered the lands in Jiangdong and he killed many heroes whose followers were willing to die for them. Besides, Sun Ce is overly confident and is unprepared, so even though he has thousands of troops, the situation is not much different from him setting out to conquer the Central Plains all by himself. If he encounters assassins, he'll have to deal with them alone. From what I observe, he'll eventually die at the hands of a common man." Guo Jia's prediction came true as Sun Ce was assassinated by the followers of Xu Gong (a commandery administrator he killed earlier) before he could even carry out his plan.(孫策轉鬬千里，盡有江東，聞太祖與袁紹相持於官渡，將渡江北襲許。衆聞皆懼，嘉料之曰：「策新并江東，所誅皆英豪雄桀，能得人死力者也。然策輕而無備，雖有百萬之衆，無異於獨行中原也。若刺客伏起，一人之敵耳。以吾觀之，必死於匹夫之手。」策臨江未濟，果為許貢客所殺。) Sanguozhi vol. 14.