|Died||208 (aged 12)|
|Courtesy name||Cangshu (traditional Chinese: 倉舒; simplified Chinese: 仓舒; pinyin: Cāngshū; Wade–Giles: Ts'ang-shu)|
|Posthumous name||Prince Ai (Chinese: 哀王; pinyin: Āi Wáng; Wade–Giles: Ai Wang)|
Cao Chong (196–208), courtesy name Cangshu, was a son of Cao Cao, a warlord who rose to power towards the end of the Han dynasty and laid the foundation of the state of Cao Wei in the Three Kingdoms period. A child prodigy, Cao Chong is best known for his ingenious method of weighing an elephant using the principle of buoyancy. He was considered by his father as a possible successor but died prematurely at the age of 12.
Cao Chong was the eldest son of Cao Cao and his concubine Lady Huan (環夫人). He had two younger brothers: Cao Ju (曹據) and Cao Yu. He was a child prodigy and already possessed the intelligence of an adult when he was around the age of five.
Principle of buoyancy
On one occasion, the southern warlord Sun Quan sent an elephant as a gift to Cao Cao. Cao Cao wanted to know the animal's weight so he asked his subordinates but no one could think of a method to measure the elephant's weight. Cao Chong said, "Place the elephant on a boat and mark the water level. Then replace the elephant with other objects until the boat is submerged to the same level. The weight of the elephant can be found by summing up the weights of all the objects." Cao Cao was delighted and he had Cao Chong's idea implemented.
According to Joseph Needham, although no official treatise in the likes of Archimedes' principle was ever written regarding buoyancy in ancient China, there were observational precedents of it in the Rites of Zhou, compiled and edited in the early Han dynasty (202 BCE–220 CE). Needham states:
Empirical use, of course, was made of [Archimedes'] principle, as in the floating of arrows and vehicle wheels in water by the [Zhou] and Han technicians, in order to determine their equilibrium and add or remove material accordingly.
In another incident, Cao Cao's saddle was chewed by rodents when it was kept in a store. The storekeepers feared for their lives because the laws were very harsh during those times of war, so they planned to tie themselves up and admit their mistake to Cao Cao in the hope of receiving a lenient punishment. Cao Chong told them, "Wait for three days before reporting the incident." He used a knife to cut holes in his clothes, making it seem as though they had been damaged by rats, and then pretended to look upset. When his father asked him, he replied, "There is a saying that a person whose clothes have been chewed by rats will encounter ill luck. Now, as this has happened to me, I fear something might happen." Cao Cao said, "This is just a superstition. There's nothing to worry about." When the storekeepers reported the saddle incident to Cao Cao three days later, Cao Cao laughed and said, "My son's clothes were with him, yet they were still chewed by rats, so it is not surprising that my saddle in the store was also damaged." He did not pursue the matter.
Favoured by his father
Cao Chong was known to be kind and understanding. He helped to review cases of indicted criminals for any injustice and successfully cleared tens of cases. When some hardworking officials landed themselves in trouble for making minor lapses, Cao Chong spoke up for them and managed to persuade his father to pardon them.
Cao Chong's intelligence and compassionate attitude, coupled with his beautiful looks, made him very outstanding among his brothers and earned him the favour of his father. Cao Cao often praised Cao Chong in front of his subordinates and had the intention of making Cao Chong his heir apparent.
Death and succession
Cao Chong became seriously ill when he was 12 and died. Cao Cao was extremely grieved. When Cao Pi (another of Cao Cao's sons) came to console his father, Cao Cao remarked, "Cao Chong's death is my misfortune, but it is to the advantage of you and your brothers."
Cao Cao shed tears whenever Cao Chong was mentioned. He had Cao Chong buried together with a deceased woman from a certain Zhen (甄) family and posthumously granted his son the appointment "Cavalry Commandant" (騎都尉). Cao Cong (曹琮), the Marquis of Wan (宛侯) and a son of Cao Chong's younger brother Cao Ju (曹據), was designated Cao Chong's heir. In 217, Cao Cong was enfeoffed as the "Marquis of Deng" (鄧侯).
In 221, after Cao Pi established the state of Cao Wei, he granted Cao Chong the posthumous title "Marquis Ai of Deng" (鄧哀侯) but elevated him to the status of a duke later, so Cao Chong became known as "Duke Ai of Deng" (鄧哀公). In 231, during the reign of Cao Pi's son Cao Rui, Cao Chong was posthumously honoured as "Prince Ai of Deng" (鄧哀王). Cao Pi once said, "My elder brother (Cao Ang) was a xiaolian and had the right to the succession. If Cangshu was around, I'd not have been able to obtain the empire."
In 222, Cao Cong was promoted to "Duke of Guanjun" (冠軍公) and his title was changed to "Duke of Jishi" (己氏公) in the following year. In 237, during Cao Rui's reign, Cao Cong was demoted to a "Marquis of a Chief District" for committing an offence and had the number of taxable households in his dukedom reduced by 300. Two years later, he was restored as the "Duke of Jishi". In 246, during the reign of Cao Fang, Cao Cong's title was renamed to "Duke of Pingyang" (平陽公). The number of households in Cao Cong's dukedom increased throughout the reigns of Cao Fang, Cao Mao and Cao Huan until it reached 1,900.
- The Sanguozhi mentioned that Cao Chong died in the 13th year of the Jian'an era (196-220) in the reign of Emperor Xian of Han. He was 13 years old (by East Asian age reckoning) when he died. Quote from Sanguozhi vol. 20: (年十三，建安十三年疾病，太祖親為請命。及亡，哀甚。) By calculation, Cao Chong's birth year should be around 196.
- (武皇帝二十五男： ... 環夫人生鄧哀王沖、彭城王據、燕王宇， ...) Sanguozhi vol. 20.
- (少聦察岐嶷，生五六歲，智意所及，有若成人之智。) Sanguozhi vol. 20.
- (時孫權曾致巨象，太祖欲知其斤重，訪之羣下，咸莫能出其理。沖曰：「置象大船之上，而刻其水痕所至，稱物以載之，則校可知矣。」太祖大恱，即施行焉。) Sanguozhi vol. 20.
- (時軍國多事，用刑嚴重。太祖馬鞌在庫，而為鼠所齧，庫吏懼必死，議欲面縛首罪，猶懼不免。沖謂曰：「待三日中，然後自歸。」沖於是以刀穿單衣，如鼠齧者，謬為失意，貌有愁色。太祖問之，沖對曰：「世俗以為鼠齧衣者，其主不吉。今單衣見齧，是以憂戚。」太祖曰：「此妄言耳，無所苦也。」俄而庫吏以齧鞌聞，太祖笑曰：「兒衣在側，尚齧，況鞌縣柱乎？」一無所問。) Sanguozhi vol. 20.
- (沖仁愛識達，皆此類也。凡應罪戮，而為沖微所辨理，賴以濟宥者，前後數十。) Sanguozhi vol. 20.
- (魏書曰：沖每見當刑者，輒探覩其冤枉之情而微理之。及勤勞之吏，以過誤觸罪，常為太祖陳說，宜寬宥之。) Wei Shu annotation in Sanguozhi vol. 20.
- (辨察仁愛，與性俱生，容貌姿美，有殊於衆，故特見寵異。) Wei Shu annotation in Sanguozhi vol. 20.
- (太祖數對羣臣稱述，有欲傳後意。) Sanguozhi vol. 20.
- (年十三，建安十三年疾病，太祖親為請命。及亡，哀甚。文帝寬喻太祖，太祖曰：「此我之不幸，而汝曹之幸也。」) Sanguozhi vol. 20.
- (言則流涕，為聘甄氏亡女與合葬，贈騎都尉印綬，命宛侯據子琮奉沖後。二十二年，封琮為鄧侯。) Sanguozhi vol. 20.
- (黃初二年，追贈謚沖曰鄧哀侯，又追加號為公。 ... 太和五年，加沖號曰鄧哀王。) Sanguozhi vol. 20.
- (魏略曰：文帝常言「家兄孝廉，自其分也。若使倉舒在，我亦無天下。」) Weilue annotation in Sanguozhi vol. 20.
- (三年，進琮爵，徙封冠軍公。四年，徙封己氏公。 ... 景初元年，琮坐於中尚方作禁物，削戶三百，貶爵為都鄉侯。三年，復為己氏公。正始七年，轉封平陽公。景初、正元、景元中，累增邑，并前千九百戶。) Sanguozhi vol. 20.
- Chen Shou. Records of the Three Kingdoms (Sanguozhi).
- Needham, Joseph (1986). Science and Civilization in China: Volume 4, Part I. Taipei: Caves Books, Ltd.
- Pei Songzhi. Annotations to Records of the Three Kingdoms (Sanguozhi zhu).