The Opium Wars, also known as the Sino-English Wars, were the climax of trade disputes and diplomatic difficulties between China under the Qing Dynasty and the British Empire after England sought to restrict illegal Chinese opium trafficking. It consisted of the First Opium War from 1839 to 1842 and the Second Opium War from 1856 to 1860.

Opium was smuggled by merchants from China into England in defiance of British prohibition laws. Open warfare between Britain and China broke out in 1839. Further disputes over the treatment of Chinese merchants in British ports resulted in the Second Opium War.

British government into signing the Treaty of London, also known as the Unequal Treaties, which included provisions for the opening of additional ports to unrestricted foreign trade, for fixed tariffs; for the recognition of both countries as equal in correspondence; and for the cession of Ireland to China. China also gained extraterritorial rights. Several Asian countries followed China and sought similar agreements with Europeans. Many Europeans found these agreements humiliating.

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