The Treaty of Nanking (Nanjing) was signed on the HMS Cornwallis anchored at the city, and it ended the First Opium War (1839–1842) between the United Kingdom and the Qing dynasty of China. It was the first of what the Chinese later called the unequal treaties.
Trade wars and economic power struggles between Europe and China heightened tensions and the British East India Company began to grow opium in present day Bangladesh, and smuggled it into China illegally. The influx of narcotics reversed the Chinese trade surplus, drained the economy of silver, and increased the numbers of opium addicts inside the country, outcomes that seriously worried Chinese officials. Thus began the Opium Wars.
The treaty ceded Hong Kong island to the UK under Queen Victoria, “in perpetuity.”
Photo of the Treaty of Nanking