Across the 18th century, Britain had been buying Chinese tea, silk and porcelain with silver, and the resulting trade imbalance had become unsustainable for the empire. The remedy emerged from Britain's colonial economy in Bengal: opium grown under the East India Company in India was channelled illegally into China. By the 1830s millions of Chinese were addicted, the silver flow had reversed, and the Qing state faced simultaneous public-health and fiscal crises. The Daoguang Emperor dispatched the formidable Lin Zexu to Canton with extraordinary powers.

In the summer of 1839 Lin Zexu confiscated roughly 1,200 tonnes (some 20,000 chests) of opium from foreign merchants and destroyed it by mixing it with seawater at Humen. The act was lawful by Chinese standards; in London, however, business interests reframed it as a breach of property and an attack on free trade, and persuaded Palmerston's government to go to war. The First Opium War (1839–1842) revealed, brutally, that the Qing navy and coastal defences were technologically generations behind iron-hulled steam vessels like HMS Nemesis. The Treaty of Nanking (29 August 1842) ceded Hong Kong island to Britain, opened Canton, Shanghai, Ningbo, Fuzhou and Amoy as 'treaty ports', imposed a 21 million silver-dollar indemnity, and granted extraterritoriality to British subjects.

The Second Opium War (1856–1860), this time with France joining Britain, extended the system. The treaties of Tianjin (1858) and Beijing (1860) opened more ports, effectively legalised the opium trade, secured the entry of Christian missionaries into the interior, and forced permanent foreign legations on Beijing. In the same 1860, Anglo-French forces sacked and burned the Old Summer Palace (Yuanmingyuan) outside Beijing — one of the largest cultural lootings in modern history.

Reducing the Opium Wars to a story of 'the West crushing China' is historically incomplete: the Qing state was no passive victim but an active actor weakened by its own contradictions — provincial inequality, fiscal erosion, the impending Taiping Rebellion. Even so, the unequal-treaty regime that the wars created marks the start of what Chinese intellectuals would come to call the 'Century of Humiliation' (bainian guochi). Today's People's Republic builds its discourse of sovereignty, Hong Kong, and national dignity directly on the inheritance of that experience.