Treaty of Nanjing: The 1842 Pact That Reshaped Hong Kong

By GlobeBids History Desk | 29 August 2026

On 29 August 1842, Britain and Qing China signed the Treaty of Nanjing, ending the First Opium War. China was compelled to open five ports to British trade, pay a substantial indemnity and cede Hong Kong Island to Britain. The agreement changed relations between the two empires, but its significance lies as much in the military coercion behind it as in its commercial terms.

The treaty became the first agreement in a series commonly described as the unequal treaties. It established the initial basis of British rule in Hong Kong, although later conventions expanded the territory under British control before sovereignty was transferred to China in 1997.

What changed on 29 August 1842

The treaty brought formal hostilities to an end after British forces had demonstrated a decisive advantage along the Chinese coast and on major waterways. Qing officials negotiated while British warships threatened further advances, leaving China with little practical ability to reject the settlement.

Its principal provisions included:

• Opening Guangzhou, Xiamen, Fuzhou, Ningbo and Shanghai to British merchants.
• Allowing British consular officials to reside at those five treaty ports.
• Ceding Hong Kong Island to Britain.
• Requiring China to pay 21 million silver dollars in indemnities.
• Ending the Cohong system that had restricted foreign commerce at Guangzhou to approved Chinese merchants.

The treaty did not itself settle every feature of the new relationship. Supplementary negotiations, including the 1843 Treaty of the Bogue, added provisions such as extraterritorial rights and most-favoured-nation treatment for Britain.

Encyclopaedia Britannica identifies the agreement as the treaty that ended the war, opened ports and transferred Hong Kong Island. Those terms created a new framework for trade, diplomacy and foreign presence in Qing China.

The opium trade and the road to war

European demand for Chinese tea, silk and porcelain had long produced a trade imbalance because Chinese merchants had limited demand for British goods. British traders increasingly supplied opium grown in British-controlled India, receiving silver that could then be used to purchase Chinese products.

Opium imports were prohibited by Qing authorities, yet smuggling expanded during the early nineteenth century. The trade generated profits for private merchants and revenue within the British imperial economy while contributing to addiction, corruption and the movement of silver out of China.

In 1839, the Qing official Lin Zexu ordered foreign merchants at Guangzhou to surrender their opium stocks. More than 20,000 chests were confiscated and destroyed at Humen. Britain treated the loss of merchants’ property and restrictions on trade as grounds for confrontation.

British military power shaped the negotiations

The First Opium War was fought from 1839 to 1842. British steamships, naval artillery and experienced expeditionary forces gave Britain an advantage over Qing coastal defences. Operations extended beyond Guangzhou as British forces captured or threatened strategically important ports and river routes.

The National Army Museum places the conflict within overlapping commercial, military and imperial ambitions. Opium was central to the crisis, but disagreements over diplomacy, legal jurisdiction and access to Chinese markets also shaped British policy.

Calling the treaty a trade agreement without this setting would obscure how its terms were obtained. It followed battlefield defeats and was negotiated under the threat of continued military action, not between parties exercising comparable power.

Five ports opened a new phase of foreign access

Before the war, most Western maritime trade with China operated through Guangzhou under the Canton system. The opening of five treaty ports distributed foreign commercial activity across a much wider stretch of the coast.

Foreign merchants gained access to designated districts, while consuls represented British interests locally. Shanghai would eventually become the most commercially important of the ports, developing foreign concessions whose administration and legal arrangements placed parts of the city beyond ordinary Qing control.

The Treaty of Nanjing also required a regular tariff arrangement. Although presented by Britain as a step towards predictable commerce, the broader treaty-port system weakened Qing control over trade and foreign activity. Other powers subsequently sought comparable privileges through their own agreements.

Why historians call it the first unequal treaty

The phrase unequal treaties refers to agreements imposed on China and other Asian states by stronger imperial powers, particularly during the nineteenth and early twentieth centuries. The description is retrospective: it was not the formal name used in the 1842 document.

The imbalance was visible in both the circumstances and consequences. Britain obtained territory, market access and financial compensation after using military force. China received an end to the immediate attack but did not gain equivalent concessions in Britain.

Later treaties widened foreign privileges and opened additional ports. The Treaty of Nanjing therefore matters not only for its individual clauses but also because it began a system through which Britain and other powers constrained aspects of Qing sovereignty.

Hong Kong’s boundaries changed under later conventions

The territory transferred in 1842 was Hong Kong Island, not the entire area later administered as British Hong Kong. Britain’s control expanded through two subsequent agreements:

• In 1860, the Convention of Beijing ceded the southern part of the Kowloon Peninsula and Stonecutters Island to Britain.
• In 1898, the Convention for the Extension of Hong Kong Territory gave Britain a 99-year lease over the New Territories and additional islands.

The approaching expiry of that lease shaped later negotiations because the leased and ceded areas had become closely integrated. The 1984 Sino-British Joint Declaration established the arrangements under which Britain transferred sovereignty over Hong Kong to China on 1 July 1997.

This sequence is important: the Treaty of Nanjing began British possession with Hong Kong Island, while later agreements produced the larger colonial territory that existed at the end of British rule.

Why Nanjing and Nanking both appear

Nanjing and Nanking refer to the same city. Nanjing is the spelling produced by the pinyin romanization system now widely used for Mandarin Chinese place names. Nanking is an older English rendering found in diplomatic records, historical books and the conventional English title of the treaty.

Consequently, Treaty of Nanjing and Treaty of Nanking are both used in English. The difference does not indicate separate agreements or locations; it reflects changing systems for representing Chinese names in the Latin alphabet.

A similar distinction appears with Beijing and Peking. Modern writing generally uses Convention of Beijing, while older sources often call the same 1860 agreement the Convention of Peking.

Britain, China and Hong Kong differently

In older British accounts, the war was often presented through naval victory, expanding commerce and the rise of Hong Kong as a port. More recent historical and museum treatments give greater attention to the opium economy, imperial expansion and the coercion used to obtain the treaty.

In China, the agreement is widely remembered as the first unequal treaty and as an early landmark in the period often called the century of humiliation, when foreign powers imposed territorial, economic and legal concessions on the Qing state and its successors.

For Hong Kong, 1842 marks the beginning of more than a century and a half of British colonial rule. Its legacy also includes later migration, war, economic transformation and the development of distinctive institutions and identities. Experiences and interpretations within Hong Kong have never been uniform.

These memories arise from different historical positions: imperial victory in Britain, coerced loss in China and a long colonial transformation in Hong Kong. Recognising those differences does not require projecting present-day political claims onto the treaty. It requires reading its commercial provisions alongside the armed force that made them possible.

Source: Encyclopaedia Britannica