The Opium War (1840-1842), also called the Anglo-Chinese War, was the most humiliating defeat China ever suffered.
From the end of the 18th century, the English kept trafficking opium into China. This trade had produced, quite literally, a country filled with drug addicts, as opium parlors proliferated all throughout China in the early part of the nineteenth century.In 1838, Lin Zexu was appointed Imperial Commissioner at Guangzhou to suppress the opium trafficking. He took action against Chinese merchants and Western traders and shut down all the traffic in opium and destroyed all the existing stores of opium of about 2,300 tons.
With the pretense of protecting trade relations, the English sent warships in June of 1840. The Chinese, with old-style weapons and artillery, were no match for the British gunships, which ranged up and down the coast shooting at forts and fought on land. The Chinese were equally unprepared for the technological superiority of the British land armies, and suffered continual defeats. Finally, in 1842, the Chinese were forced to agree to an inglorious peace with the signing of the Treaty of Nanjing. The treaty imposed on the Chinese was weighted entirely to the British side. And China became a semi-feudal and semi-colonial society.