In 1854, Britain requested the ratification of the Treaty of Nanking signed in 1842 in order to advance its interests in China. The request, though supported by France and the United States, were rejected by the government of Qing Dynasty.

In October 1856, the allied troop of Britain and France waged the Second Opium War. Guangzhou was captured in December 1857, and so was Dagu Fort in May 1858. Emperor Xianfeng of Qing Dynasty sent chief scholar Gui Liang to negotiate peace in Tianjin. In June, the Treaty of Tianjin was signed, granting the establishment of foreign legations in Beijing, the increasing number of trading ports, the rights of foreigners to trade and evangelize freely inside China, and the payment of reparations to britain and France.

In 1859, Britain and France requested the removing of fortification around the Baihe River. They were rejected again by Qing government. In June, the allied fllet lauched from Chinese army. A dozen warships were lost with a total casualty of over 600. The allied troop retreated.

In August 1860, the British and French allied forces came back and managed to capture Dagu Fort and Tianjing. The capital of Beijing was threatened and Emperor Xianfeng fled to Rehe (today's Chengde, Hebei province) in panic. On October 6th, the allied troops broke into the world-famous Yuanmingyuan Garden and burned it. Soon after, Qing government was forced to sign the Treaty of Peking with Britain, France and Russia. By this treaty, Kowloon was ceded, Tianjin became a trading port, and reparations were increased. The Second Opium War lasted four years and ended again with Chinese defeat and the unequal treaties of humiliation and forfeiting sovereignty.