In late March 1839, Commissioner Lin Zexu confined foreign traders, mostly British, to their factories in Canton, cutting off supplies until they surrendered their opium stocks. Lin's crackdown on the illegal drug trade, which had addicted millions of Chinese and drained silver from the treasury, humiliated British merchants and gave London a pretext for military intervention that erupted into the First Opium War the following year.
Lin Zexu, a Confucian scholar-official famed for his integrity, had been dispatched by the Daoguang Emperor specifically to stamp out the opium trade that British merchants, backed by the East India Company, had used to reverse China's centuries-old trade surplus. Lin's siege forced British superintendent Charles Elliot to eventually hand over more than 20,000 chests of opium, which Lin had dissolved in seawater, lime, and salt and flushed into the sea over 23 days.
Lin even wrote a now-famous letter to Queen Victoria appealing to her conscience, asking how Britain could justify poisoning another nation while banning opium at home. The letter apparently never reached her. Britain's response was not moral reflection but naval retaliation, launching the First Opium War in 1840, which ended in a crushing Chinese defeat and the humiliating Treaty of Nanking, ceding Hong Kong to British control for over 150 years.