Background

Feng Changqing's family was from Yishi (猗氏, in modern Yuncheng, Shanxi). His maternal grandfather had committed a crime and was exiled to Shymkent, to serve in the Tang Dynasty army, as part of the army for Anxi Circuit (安西, headquartered in modern Aksu Prefecture, Xinjiang) with the responsibility to guard the south gate of the non-Han portion of the city. Feng's grandfather was learned, and often sat with Feng on the gate tower to teach him, giving Feng a broad education. After his grandfather died, Feng was in his 30s, but was poor and alone. At that time, Fumeng Lingcha (夫蒙靈詧) was the military governor (jiedushi) of Anxi, and one of the generals serving under Fumeng was Gao Xianzhi. Gao was considered capable, and retained a corps of 30 guards with handsome clothes. Feng submitted a petition to Gao, asking to be one of the guards, but as Feng was thin, ugly, and walking with a limp with short legs, Gao rejected him. He submitted another petition the next day, and Gao responded, "I already have enough guards. Why come again?" Feng angrily responded:

Gao still did not accept him. Feng stayed outside Gao's house door waiting for Gao to enter and leave, for tens of days. Eventually, Gao could not stand it and added him to the guard corps.

Army service in the Xiyu region

At one point, near the end of Emperor Xuanzong's Kaiyuan era (727-741), when Gao Xianzhi had been promoted to be Fumeng Lingcha's deputy, Fumeng had put Gao in charge of attacking the rebellious Daxi (達奚) tribe. Gao was successful in the attack, and was able to kill or capture nearly all of the rebels. Without having been directed by Gao to do so, Feng drafted a report of the victory on Gao's behalf, clearly stating the geographical features, the strategies used, and details of the victory. He presented it to Gao, who was surprised as how well-written it was and how it had anticipated everything Gao wanted to say. Gao submitted the report written by Feng to Fumeng, unsealed and written on a large banner, to allow the tribes on the way to see the victory. After Gao returned to Anxi headquarters, Fumeng held a feast in his honor, and Fumeng's assistants Liu Tiao and Dugu Jun (獨孤峻) both anxiously asked Gao, "Who was it who wrote the report? How did you, Lord, retain such an impressive person?" Gao responded, "It was my guard Feng Changqing." Liu and Dugu were surprised, and they invited Feng to join the feast as well. Feng thereafter became known to the Anxi headquarter staff, and was given the honorific title of castle defender and made Gao's assistant. He was thereafter several times promoted in rank.

In 747, Feng served under Gao in the conquest of Lesser Bolü (小勃律, a city state centering on modern Gilgit, Pakistan). Around the new year 748, after Gao was promoted to be the military governor of Anxi, replacing Fumeng, Feng, at Gao's recommendation, received an honorary commission on the staff of Emperor Xuanzong's oldest son Li Cong the Prince of Qing, but remained at Anxi and served as Gao's assistant, with the position only below the deputy military governor. He often was put in charge of the headquarters when Gao was out conducting campaigns. Gao entrusted his household matters, however, to Zheng Dequan (鄭德詮), the son of Gao's wet nurse, whom Gao treated as a brother and therefore was powerful in the army. On one occasion, because of this, Zheng did not, as was proper under military protocol, salute Feng as a superior officer. Feng ordered Zheng to report to headquarters, and then locked the doors and stated to him:

He then yelled out, "You, general, must temporarily die to affirm good order in the army." He thus caned Zheng 60 times, and Zheng died. Gao's wife and wet nurse cried bitterly outside but could not get in to save Zheng. They submitted an accusation to Gao, but all Gao said upon reading the accusation was, "Alas, he died?" When he and Feng met again, neither of them spoke of the matter, as Gao was impressed with Feng's discipline. In addition, when two other generals committed crimes, Feng also killed them, thus reaffirming military discipline.

In 751, Gao was initially set to be made the military governor of Hexi Circuit (河西, headquartered in modern Wuwei, Gansu), and he asked that Feng be made his assistant. (Subsequently, though, due to machinations of An Sishun, then military governor of Hexi, who wanted to remain there, Gao was instead recalled to the capital to serve as a general of the imperial guards.) When Wang Zhengjian was named as the military governor of Anxi to replace Gao, he asked Feng to serve as his deputy. When Wang died in 752, Feng was made acting military governor. In 753, he attacked Greater Bolü and forced its submission to Tang. In 754, when he went to Chang'an to meet Emperor Xuanzong, he was given a number of honors and a mansion in Chang'an, and his deceased parents also received posthumous honors; soon thereafter, he was officially made military governor. It was said that Feng was hard-working and frugal, and sometimes rode a mule while commanding the army. He was strict in discipline and awards.

Death

In 755, An Lushan, the military governor of Fanyang Circuit (范陽, headquartered in modern Beijing), launched a rebellion against Emperor Xuanzong's rule. Late that year, Feng Changqing arrived in Chang'an to meet with Emperor Xuanzong. When they met on December 23, Emperor Xuanzong asked him what should be done. Feng, initially believing that An's rebellion could be defeated quickly, volunteered to head to the eastern capital Luoyang to defend it and then to counterattack. Emperor Xuanzong agreed, and commissioned Feng as the military governor of Fanyang and Pinglu (平盧, headquartered in modern Chaoyang, Liaoning) to replace An. That day, Feng headed to Luoyang to gather troops and prepare for defenses. Once he got there, he gathered 60,000 men and destroyed the Yellow River bridge to prepare for attack, but quickly found out that he had a major problem—there were insufficient weapons available for his troops. Meanwhile, An crossed the Yellow River elsewhere and captured Chenliu (陳留, roughly modern Kaifeng, Henan) and Yingyang (滎陽, roughly modern Zhengzhou, Henan) Commanderies, and then arrived at Luoyang. Feng tried to defend with his inadequately-supplied troops, but could not. An entered the city, and Feng was forced to destroy the western gate in order to get out of Luoyang and retreat west.

Meanwhile, Gao Xianzhi, who was the acting supreme commander of the forces, was stationed at Shan Commandery (陝郡, roughly modern Sanmenxia, Henan). Feng retreated to Shan, where Emperor Xuanzong sent an order stripping him of titles but allowing him to remain in the army under Gao. Feng warned Gao that Shan Prefecture was difficult to defend—that they should retreat to Tong Pass and fortify its defenses against An's attack. Gao agreed, and they abandoned Shan and withdrew to Tong Pass. When An later arrived, he could not capture it. Meanwhile, though, Feng was detecting signs that he might be in trouble, and anticipatorily wrote a final submission to Emperor Xuanzong, warning him about An's strengths and cautioning against overconfidence, as the other officials at the time generally believed that An could be defeated quickly.

Meanwhile, during the campaign, Gao had caused much offense against the eunuch Bian Lingcheng, serving as his monitor, as Bian was making demands of him that he was not meeting. When Bian returned to Chang'an, he accused Feng of exaggerating An's strength, and accused Gao of improperly abandoning Shan as well as corruptly withholding food supplies and imperial rewards to soldiers for personal benefit. Emperor Xuanzong, believing Bian, issued edicts for Feng's and Gao's executions. After Bian returned to Tong Pass, he first read the edict for Feng's execution. Feng, after giving his submission to Bian to submit to Emperor Xuanzong, was beheaded, and upon the completion of that execution, Bian then read the second edict ordering Gao's execution. Gao cried out:

The soldiers cried out for Gao as well, but Bian still beheaded Gao. As Gao was to be killed, he looked at Feng's body and stated:

生平

父母早亡，外祖父犯罪，隨外祖父流放安西。初在高仙芝部任判官，天寶六年（747年）隨高仙芝擊敗小勃律國（在今克什米爾西北部）。天寶十一年（752年）唐玄宗任命封常清為安西副都護，第二年，封常清率軍攻破大勃律國（今克什米爾巴爾蒂斯坦）也是史稱大勃律之戰。天寶十三年（754年），封常清入朝，封御史大夫。

天寶十四年（755年），范陽節度使的安祿山叛亂，佔黃河以北大部份地區，唐玄宗命封常清率軍平叛，於洛陽募兵得六萬人，多富家子弟，更由於承平日久，民不知戰，而六軍宿衛多市井劣徒，不能受甲，實為烏合之眾，反觀「祿山精兵，天下莫及」，六日之內，三戰皆敗，只得放棄洛陽，西奔陝郡。唐玄宗削其官爵，讓他以布衣身份在高仙芝軍中效力，他向高仙芝提議退保潼關以拒之，此舉果然奏效，安祿山麾下之崔乾祐一時不能攻下。後封常清遭監軍邊令誠陷害：「常清以賊搖眾，而仙芝棄陝地數百里，又盜減軍士糧賜。」玄宗聽信謠言，派遣邊令誠赴軍中，天寶十四年十二月二十一日（756年1月27日）和高仙芝一起被冤殺於潼關軍中。

封常清臨刑前說：「常清所以不死者，不忍污國家旌麾，受戮賊手，討逆無效，死乃甘心。」把自己的遺表交給邊令誠，請他呈送玄宗，表曰：「臣今將死抗表，陛下或以臣失律之後，誑妄為辭；陛下或以臣欲盡所忠，肝膽見察。臣死之後，望陛下不輕此賊，無忘臣言，則冀社稷複安，逆胡敗覆，臣之所願畢矣。仰天飲鴆，向日封章，即為尸諫之臣，死作聖朝之鬼。若使歿而有知，必結草軍前。迴風陣上，引王師之旗鼓，平寇賊之戈鋌。生死酬恩，不任感激，臣常清無任永辭聖代悲戀之至。」遂從容就死。封常清被斬後，軍隊由李承光暫領。此後戰事遂曠日持久。

相貌

《舊唐書·封常清傳》記載封常清「細瘦，目類，腳短而跛……其貌寢」，《新唐書·封常清傳》記載「以高仙芝為都知兵馬使。嘗出軍，奏傔從三十餘人，衣褷鮮明，常清慨然投牒請豫。常清素瘠，又腳跛，仙芝陋其貌，不納。」，意指封常清不但相貌醜陋，而且身材瘦小，斜眼，很可能還有，走路時不平衡，並因此應征高仙芝侍從時一度遭到高仙芝拒絕。《舊唐書·封常清傳》還記載封常清「性勤儉，每出征或乘驛，私馬不過一兩匹」，《新唐書·封常清傳》記載「性勤儉，耐勞苦，出軍乘騾，私廄裁二馬」。就是說封常清出征時乘騾（註：舊唐書記載「或乘驛」意思是每次出征有時乘騾，而新唐書僅記載「出軍乘騾」），不像一般將帥一樣騎著馬出征，據《舊唐書·封常清傳》記載，就連動身到東都洛陽招募時也是「乘驛赴東京召募」，這或許是因為身體的缺陷導致如此，也可能他長的並不高。