Trade between China and the United Kingdom of Great Britain and Ireland began throwing an increasing deficit to the East India Company which had a monopoly of trade with China. The British supported the East India Company to pursue trade with the East Indies, but which ended up trading mainly with the Indian subcontinent and Qing China.
Early in the 19th century British merchants began smuggling opium into China in order to balance their purchases of tea for export to Britain.
As the East India Company was not able to offset and balance the Chinese tea export to them, then they resorted to impose Indian opium cultivated in the Indian cotton fields in order to reduce and eliminate the huge trade deficit with China.
Opium Wars Map. Here is a map showing the route from the opium warehouses in Bombay and Calcutta to Canton in China.
The Chinese rejected proposals to legalize opium and rather imposed a death penalty for opium smuggling in 1838. Drug Czar, Lin Zexu was appointed to curb smuggling and abolished trade with the East India Co. This resulted in the First Opium War.
The East India Company iron steam ship Nemesis, commanded by Lieutenant W. H. Hall, with boats from the Sulphur, Calliope, Larne andStarling, destroying the Chinese war junks in Anson's Bay, on 7 January 1841.
In 1839, the Chinese drug czar seized more than 1,400 tons of opium and expelled the British traders who went to plead with their British government to defend them. The international embarrassment arises with the declaration of war on China and the immediate dispatch of gunships to bomb the Chinese coast.
The British applied full strength and sailed up the Yangtze River to Nanjing in 1842 and obliged the Chinese emperor to sign the Treaty of Nanking which forced China to open five ports to British free trade: Amoy, Canton, Foochow, Ningbo and Shanjai.
The role of Opium in 19th Century British Empire
This was the beginning of so-called "Unequal Treaties" of Western powers with China.