Hengyang (simplified Chinese: 衡阳; traditional Chinese: 衡陽; pinyin: Héngyáng; Mandarin pronunciation: [xə̌ŋ.jǎŋ];) is the second largest city of Hunan Province, China. It straddles the Xiang River about 160 km (99 mi) south of the provincial capital of Changsha. Its built-up (or metro) area made of 4 out of 5 urban districts was home to 1,075,516 inhabitants at the 2010 census.
Its former name was Hengzhou (衡州, p Héngzhōu). This was the capital of a prefecture in the Tang Dynasty's Jiangnan and West Jiangnan circuits. Li Jingxuan was banished to superintendence of Hengzhou after feigning an illness and attempting to usurp control of the legislative bureau at Chang'an against the Gaozong Emperor's wishes in AD 680. Following the AD 705 coup that removed the Empress Wu Zetian from power, her ally Li Jiongxiu was also briefly demoted to superintendence of this province. During the reign of Emperor Muzong, the chancellor Linghu Chu was also demoted to this province for his underlings' alleged corruption.
In the 750s, the superintendent of Hengzhou Chen Xi'ang not only ruled his own region but also used his private army to dominate his nominal superior, the military governor Zhang Weiyi headquartered in Jing Prefecture (modern Jingzhou). Upon Zhang's replacement by the former chancellor Lü Yin in 760, however, Chen was placated and then killed in a surprise attack.
During the reign of the Tang emperor Xizong, Zhou Yue overthrew first the prefect of Hengzhou Xu Hao in 881 and then the agent of the rebel Qin Zongquan in the capital of the Qinhua Circuit at Tan Prefecture (modern Changsha) in 886. Xizong confirmed Zhou Yue in all his posts, renaming his circuit Wu'an. Xizong's brother then gave him additional authority over West Lingnan Circuit (modern Guangxi). Shortly after, in 893, Deng Chune and Lei Man attacked and killed him.
Other superintendents included Qi Ying and Xiao Ye.
After initially falling to agrarian rebels under Yang Shiyuan, Hengzhou was recovered by the lord of Wu'an Ma Yin and formed part of his power base during the collapse of the Tang. He initially supported the Later Liang, then declared himself king in his own right during the Five Dynasties and Ten Kingdoms period.
During the Revolt of the Three Feudatories, Wu Sangui declared himself Emperor of the Great Zhou and established an imperial court at Hengzhou in 1678 before dying of illness later that year. His grandson Wu Shifan then retreated to Yunnan, and the Ming recovered Hengzhou the next year.
The Battle of Hengyang (See: Defense of Hengyang) was the longest defense of a single city of the entire Second Sino-Japanese War. When Changsha fell to the Imperial Japanese Army on June 19, 1944, Hengyang became their next target. The reorganized 11th Army, consisting of 10 divisions, 4 brigades, and over 110,000 men, assumed the task of attacking Hengyang. It was part of the Japanese Itchi-Go offensive
In the 19th century, Hengzhou was known in English as Hengchow. A Roman Catholic diocese of Hengzhou was established, although periodically suppressed. This was suffragan to the Archbishop of Changhsha following its elevation in 1946.
Hengyang has a humid subtropical climate (Köppen Cfa), with four distinct seasons. Spring is subject to heavy rainfall, while the summers are long, hot, and humid with lesser rainfall, and autumn is comfortable and rather dry. Winter is rather brief, but cold snaps occur with temperatures occasionally dropping below freezing, and while not heavy, rain can be frequent. The monthly daily mean temperature ranges from 5.8 °C (42.4 °F) in January to 29.6 °C (85.3 °F) in July.