In 1757, the Qing government restricted most European maritime trade to Guangzhou (Canton) under what became known as the Canton System. Foreign merchants were confined to a small riverfront district and had to deal through approved Chinese merchant firms (the Cohong). This system set the stage for later conflicts over access, prices, and legal authority.
Qing policy tightened in the late 18th century, reaffirming Guangzhou as the only legal port for most foreign commerce. By restricting foreign contact and routing trade through the Cohong, the Qing sought to manage security and protect state authority. The restrictions also fueled foreign complaints about delays, fees, and limited market access.
From the 1770s, the British East India Company began selling Indian opium to Chinese merchants as a way to pay for high-demand Chinese goods such as tea. Although the trade was formally outside Qing approval, it grew because it generated large profits and helped reduce Britain’s need to pay silver for imports. This created rising social and fiscal pressures inside China as opium use spread.
In 1793, Britain sent Lord Macartney to seek expanded trade and diplomatic relations with the Qing court. The mission failed to secure the changes Britain wanted, leaving the Canton System largely intact. The episode reinforced British interest in finding leverage—commercial or military—to open China’s markets more widely.
As opium consumption and smuggling increased, the Qing state attempted to stop the trade through prohibition. Enforcement was difficult because the profits were high and corruption was common in coastal trading networks. The continued inflow of opium became tied to wider concerns about social harm and silver leaving China through illicit payments.
In late 1838, the Daoguang Emperor appointed Lin Zexu as imperial commissioner with special powers to end the opium trade centered on Guangzhou. Lin’s appointment signaled that the Qing court was shifting from uneven enforcement to a major crackdown. His actions would soon trigger a direct confrontation with British merchants and officials.
Beginning June 3, 1839, Lin Zexu oversaw the destruction of a large quantity of confiscated opium at Humen, near the Pearl River. The destruction demonstrated Qing determination to enforce the ban and to punish foreign-linked smuggling. Britain treated the losses and the broader challenge to its commercial interests as grounds for war.
Fighting broke out in 1839 as Britain used naval power to press for commercial and diplomatic concessions after the opium crackdown. The conflict exposed Qing military vulnerabilities against industrial-era forces and logistics. It also shifted the dispute from smuggling enforcement to treaty-based demands for market access and legal privileges.
On August 29, 1842, the Treaty of Nanjing ended the First Opium War and dismantled key parts of the Canton System. It opened five ports to British trade (including Shanghai) and required indemnity payments and the cession of Hong Kong. The treaty became the foundation for the treaty port system and later “unequal treaties.”
On October 8, 1843, Britain and Qing China signed the Supplementary Treaty of the Bogue to clarify and extend the Treaty of Nanjing. It granted Britain extraterritoriality, meaning British subjects in China would be tried under British rather than Qing law, and included a most-favored-nation provision. These legal changes created semi-autonomous foreign enclaves inside Qing territory.
In 1844, the United States (Treaty of Wanghia) and France (Treaty of Whampoa) negotiated treaties that extended treaty port access and reinforced extraterritoriality using most-favored-nation clauses. These agreements broadened the treaty system beyond Britain and further reduced Qing control over foreign residents and trade rules. The result was a growing multinational treaty port order along China’s coast.
On October 8, 1856, Qing officials boarded the Arrow, a Chinese-owned vessel registered under the British flag, and arrested crew members in Guangzhou. Britain treated the incident as an insult and a chance to demand expanded treaty rights, while France joined under separate grievances. The dispute escalated into a new war aimed at widening foreign access and influence.
In June 1858, after military pressure, Qing China signed the Treaty of Tianjin with Britain, France, the United States, and Russia. The treaties opened additional ports and permitted foreign diplomatic presence in Beijing, while also expanding missionary activity. Critically, they effectively legalized the import of opium, tying the drug trade directly to treaty-based commerce.
In October 1860, Qing China accepted the Convention of Beijing (Beijing Convention), ending the Second Opium War and confirming the Tianjin treaties. The settlement expanded foreign privileges and strengthened the treaty port framework that shaped trade, law, and urban governance in many coastal and river cities. By 1860, the opium trade and the treaty port system had become central mechanisms through which industrial-era powers extracted commercial access and influence in China.
Opium Trade, the Opium Wars, and the Treaty Port System in China (1773-1860)