The Second Opium War
The Second Opium War (1856–1860), also called the Arrow War, grew out of British determination to extend the trading rights won in the First Opium War, which had ended with the Treaty of Nanking in 1842. The seizure of the ship Arrow at Canton in 1856 gave Britain its pretext, and France joined the war after the execution of a French missionary. The background is covered in our article on the Opium Wars.
The Treaties of 1858
After Canton fell and the Anglo-French fleet took the Dagu forts guarding the approach to Tianjin, the Qing agreed in June 1858 to the Treaty of Tianjin. It opened further ports to foreign trade, allowed foreigners to travel in the interior, gave Christian missionaries freedom to work there, and allowed foreign envoys to reside in Beijing. The opium trade was legalised under tariff agreements concluded the same year.
A month earlier, in May 1858, China had signed the Treaty of Aigun with Russia. It moved the border to the Amur River and restricted navigation on the Amur, Sungari and Ussuri rivers to Chinese and Russian vessels.
The Fall of Beijing and the Burning of the Palaces
The court, and the emperor himself, resisted above all the idea of foreign envoys living permanently in the capital. In June 1859, when British and French envoys arrived to exchange ratifications, their fleet was refused passage at Dagu and suffered heavy losses in the attempt to force it.
The allies returned in greater strength in 1860. In August they took the Dagu forts, then Tianjin, and advanced on Beijing. In September the emperor left the capital for the summer retreat at Chengde in Jehol, officially for the autumn hunt, leaving his brother Prince Gong to negotiate. His health, already poor, declined further there, and rival factions formed at court.
In October 1860 Anglo-French troops entered Beijing and looted the Yuanmingyuan, with its vast imperial collections. In reprisal for the torture and killing of allied prisoners, the British envoy Lord Elgin ordered the Yuanmingyuan burned, and the nearby Qingyiyuan, the site of the later Summer Palace, was also destroyed.
The Convention of Beijing
Days later Prince Gong signed the Convention of Beijing. China ratified the Treaty of Tianjin, opened Tianjin itself to trade, ceded the southern part of the Kowloon peninsula to Britain, and agreed to pay Britain and France indemnities of eight million taels each. A separate agreement with Russia confirmed the Treaty of Aigun and ceded the lands east of the Ussuri River.