British Hong Kong was not a single legal territory but three, each acquired under different treaties with very different terms. The Kowloon Peninsula was ceded to Britain in perpetuity under the 1860 Convention of Peking, meaning Britain owned it outright with no expiration date. The New Territories, by contrast, was only leased for 99 years under the 1898 Convention for the Extension of Hong Kong Territory, meaning it had a hard expiration date of June 30, 1997.
This distinction between cession and lease is the core of why the Kowloon Peninsula and the New Territories had different legal fates. It is also why all of Hong Kong returned to China in 1997 rather than just the leased portion. Understanding this requires walking through three separate treaties signed across six decades of British colonial expansion.
I have spent years studying colonial treaty law and Hong Kong’s unique history, and the story of these legal distinctions reveals how decisions made in the nineteenth century shaped the geopolitical reality of the 1997 handover and continue to echo through to 2026 and beyond.
Table of Contents
The Three Treaties That Shaped Hong Kong
Britain acquired Hong Kong in three separate stages, each through a different treaty following conflicts with Qing Dynasty China. Each treaty granted Britain different legal rights over different pieces of territory.
The first acquisition came in 1842 with the Treaty of Nanking, which ended the First Opium War and ceded Hong Kong Island to Britain in perpetuity. The second came in 1860 with the Convention of Peking, which ended the Second Opium War and ceded the Kowloon Peninsula south of Boundary Street in perpetuity. The third arrived in 1898 with the Convention for the Extension of Hong Kong Territory, which leased the New Territories for 99 years.
Two of these treaties granted permanent ownership. One granted only a lease with a fixed end date. That single difference created one of the most consequential legal puzzles of the twentieth century.
1842: Hong Kong Island Ceded Under the Treaty of Nanking
The story begins with the First Opium War (1839 to 1842), a conflict triggered by China’s efforts to suppress the British opium trade within its borders. When Britain won, Qing China was forced to sign the Treaty of Nanking on August 29, 1842.
Article 3 of the Treaty of Nanking stated that China ceded Hong Kong Island to Britain “in perpetuity.” This was a full cession, meaning sovereignty transferred permanently. Under international law of the era, Britain now owned Hong Kong Island outright, with no expiration and no obligation to ever return it.
This was the foundation of British Hong Kong. The island became a Crown colony, and from this small base Britain would expand its foothold on the Chinese coast over the following decades. The treaty was what Chinese governments later called an “unequal treaty,” imposed through military force rather than genuine negotiation, but in legal terms it transferred sovereignty permanently.
Hong Kong Island covers about 80 square kilometers. It was valuable as a deep-water port and trading post, but it was small. British merchants and military strategists quickly realized that the island alone was not enough to secure their position.
1860: The Kowloon Peninsula Ceded Under the Convention of Peking
The Second Opium War (1856 to 1860) gave Britain the pretext to expand. When it ended, the Convention of Peking was signed on October 24, 1860. This treaty ceded the southern part of the Kowloon Peninsula to Britain, again in perpetuity.
Specifically, the Convention of Peking transferred the stone-cutters’ island of Stonecutters and the portion of the Kowloon Peninsula lying south of what became known as Boundary Street. This gave Britain permanent control of the harborside land directly opposite Hong Kong Island, completing the encirclement of one of the world’s finest natural harbors.
Like the Treaty of Nanking before it, the Convention of Peking used the language of permanent cession. Britain did not lease Kowloon. It owned Kowloon. Under the treaty’s terms, sovereignty over this strip of the peninsula transferred absolutely and forever.
Only about 3 square miles (roughly 7.8 square kilometers) of the Kowloon Peninsula south of Boundary Street could be developed by the colonial government. This small but strategically vital strip became the urban core of Kowloon, home to dense neighborhoods, commercial districts, and the famous Kai Tak Airport runway approach.
Boundary Street: The Original Dividing Line
Boundary Street became the legal and geographic line that separated permanently ceded Kowloon from the later New Territories lease. Everything south of Boundary Street was British-owned outright. Everything north would, after 1898, be only leased.
This distinction mattered enormously in daily administration. Land south of Boundary Street could be sold as freehold property. Land north of it, in the leased New Territories, could only be granted on terms that expired with the lease itself.
The term “New Kowloon” later emerged to describe the area north of Boundary Street but south of the Kowloon hills, which was developed as an urban extension of Kowloon even though it legally remained part of the leased New Territories. This created confusing administrative boundaries that persisted through the entire colonial period.
1898: The New Territories Leased Under the Second Convention of Peking
The legal fate of the New Territories diverged sharply from Kowloon’s. On June 9, 1898, Britain and Qing China signed the Convention for the Extension of Hong Kong Territory, sometimes called the Second Convention of Peking. This treaty did not cede territory. It leased it.
Under this convention, Britain obtained a 99-year lease on a vast area of land north of Boundary Street, stretching all the way to the Sham Chun River (today’s Shenzhen River). The leased area included approximately 235 islands and the great majority of what would become Hong Kong’s total land mass, roughly 86 percent of the entire territory.
The lease was rent-free. Britain paid nothing for the use of this land. But the treaty was explicit that sovereignty remained with China and that the lease would expire on June 30, 1997. After that date, the land would revert to Chinese control.
The Convention for the Extension of Hong Kong Territory transformed the scope of British Hong Kong. The colony went from a modest collection of harbor-side settlements to a territory with room for reservoirs, agriculture, military installations, and future urban expansion. But every inch of that expansion came with a ticking clock.
Why 99 Years? The British Law Limitation
Many people wonder why Britain chose exactly 99 years rather than 50, 75, or 150. The answer lies in British domestic property law.
Under English common law, a leasehold of 99 years was the standard maximum duration for what lawyers called a “lease for lives” or a long commercial lease. Leases longer than 99 years were unusual and in some contexts legally awkward under British property traditions. The 99-year figure was simply the conventional upper limit that British legal practice recognized.
This was not unique to Hong Kong. Britain applied 99-year leases in other colonial concessions around the world, including Weihaiwei on the Shandong Peninsula and portions of the Kiautschou Bay concession arrangements. The duration was a product of British legal culture, not Chinese negotiation.
From the British perspective in 1898, 99 years must have seemed almost impossibly distant. Queen Victoria was still on the throne. The British Empire was near its peak. Few policymakers in London imagined that the lease’s expiration would ever become a practical concern during their lifetimes or even their grandchildren’s lifetimes.
Claude MacDonald and “As Good As Forever”
Sir Claude MacDonald, the British diplomat who negotiated the convention, reportedly considered the 99-year lease duration to be “as good as forever.” This comment captures the imperial confidence of the era.
MacDonald believed that long before the lease expired, circumstances would have changed so dramatically that the original terms would be irrelevant. He was half right. Circumstances did change beyond recognition. But rather than making the lease irrelevant, those changes made its expiration one of the defining diplomatic crises of the late twentieth century.
The Kowloon Walled City Anomaly
One of the most fascinating footnotes in this legal history is the Kowloon Walled City. When the 1898 convention was signed, China insisted on retaining jurisdiction over a small military outpost within the leased territory.
The Kowloon Walled City was a small fortified settlement just north of Boundary Street, within what was now the leased New Territories. The convention’s terms specifically exempted it from the lease, meaning that Chinese officials retained jurisdiction over this tiny enclave even as British authority surrounded it on all sides.
This created a bizarre legal no-man’s-land. Britain controlled everything around the Walled City, but China retained nominal authority inside its walls. In practice, the situation became even stranger when British troops moved into the Walled City in 1899 to assert control and Chinese officials were expelled.
For most of the twentieth century, the Kowloon Walled City existed in a gray zone of jurisdictional ambiguity. Neither the British colonial government nor the Chinese government fully administered it. This legal vacuum allowed the Walled City to grow into one of the most densely populated and unregulated urban areas on Earth, a sprawling block of interconnected buildings housing tens of thousands of people at its peak.
The Walled City was finally demolished in 1993 and 1994 ahead of the handover, and the site is now a public park. But its existence illustrates how the overlapping legal statuses of ceded and leased territory created complications that persisted for nearly a century.
Why All of Hong Kong Returned in 1997, Not Just the New Territories
This is the question that sits at the heart of why the Kowloon Peninsula and the New Territories had different legal fates. If only the New Territories was leased, why did Britain return the permanently ceded territories of Hong Kong Island and Kowloon as well?
The short answer is that returning only the New Territories was practically impossible. The slightly longer answer involves geography, infrastructure, and Chinese diplomatic pressure.
The Practical Impossibility of Splitting Hong Kong
By the 1980s, when Britain and China began negotiating the territory’s future, Hong Kong had grown into a single integrated metropolis of more than five million people. The New Territories accounted for roughly 86 percent of Hong Kong’s land area and contained essential infrastructure that the ceded areas could not survive without.
The territory’s water supply came largely from reservoirs in the New Territories and from rivers along the border with China. Hong Kong Island and ceded Kowloon simply did not have enough fresh water to sustain their populations independently.
Kai Tak Airport, Hong Kong’s primary airport until 1998, sat partly in ceded Kowloon but its flight paths and operational infrastructure depended on surrounding areas. The British military also maintained Shek Kong Airfield in the New Territories, which was critical to any defense arrangement.
The ceded territories of Hong Kong Island and Kowloon had become deeply interdependent with the leased New Territories. Roads, rail lines, water mains, power grids, and housing estates crossed the Boundary Street line as if it did not exist. Splitting them would have meant amputating the body of Hong Kong from its limbs.
China’s Position: No Partial Return
China’s stance throughout the negotiations was clear and unwavering. Beijing considered all three treaties to be “unequal treaties” imposed under duress and refused to recognize their legitimacy. From China’s perspective, all of Hong Kong, including the permanently ceded territories, rightfully belonged to China.
When Margaret Thatcher traveled to Beijing in 1982 to begin negotiations, she initially explored the possibility of retaining British sovereignty over Hong Kong Island and Kowloon while returning only the leased New Territories. The Chinese government under Deng Xiaoping rejected this outright.
Deng made it plain that China would accept nothing less than the full return of all Hong Kong territory. He reportedly raised the possibility of simply taking the territory by force if negotiations failed, a threat that, whether bluster or genuine, left Britain with little leverage.
Britain recognized that it had no realistic military or diplomatic option to retain part of Hong Kong. The ceded territories could not survive without the leased New Territories, and China would not accept a partial handover. The only viable path was to negotiate the return of everything under terms that would protect Hong Kong’s economic system and way of life for a transition period.
The Sino-British Joint Declaration and One Country Two Systems
The result of these negotiations was the Sino-British Joint Declaration, signed on December 19, 1984, and registered with the United Nations. Under this agreement, Britain agreed to return all of Hong Kong to China on July 1, 1997.
In exchange, China committed to the “One Country, Two Systems” principle, under which Hong Kong would become a Special Administrative Region of China and would retain its capitalist economic system, its legal system, and a high degree of autonomy for 50 years.
The Joint Declaration established that Hong Kong’s existing way of life would remain unchanged until 2047, a date exactly 50 years after the handover. This was the framework that resolved the practical problem created by the different legal fates of the three territories.
By treating all of Hong Kong as a single unit to be returned together under a unified transition arrangement, the Joint Declaration effectively papered over the legal distinctions between ceded and leased territory. In the end, it did not matter whether a particular piece of land had been permanently ceded or merely leased. All of it went back to China on the same date under the same terms.
The handover ceremony on the night of June 30, 1997, was watched by millions around the world. The British flag was lowered, the Chinese flag was raised, and the 156 years of British colonial rule in Hong Kong came to an end. The different legal fates of the Kowloon Peninsula and the New Territories, which had seemed so important in treaty documents, were resolved in a single evening.
FAQs
Why was Hong Kong leased for 99 years?
The 99-year lease duration came from British domestic property law, where 99 years was the standard maximum for long-term leaseholds. Britain used the same 99-year convention in other colonial concessions, including Weihaiwei. The figure reflected British legal tradition rather than any specific negotiation with China.
Why did Britain return all of Hong Kong instead of just the New Territories?
The New Territories made up roughly 86 percent of Hong Kong’s land area and contained essential infrastructure including water reservoirs, the border with China, and military airfields. Hong Kong Island and ceded Kowloon could not function independently without the New Territories. Additionally, China refused to accept a partial return, insisting on the full handover of all territory regardless of treaty status.
Is Kowloon part of the New Territories?
No. The original Kowloon Peninsula south of Boundary Street was permanently ceded to Britain in 1860 under the Convention of Peking. The New Territories, leased in 1898, begins north of Boundary Street. However, the area called New Kowloon, north of Boundary Street but south of the Kowloon hills, was developed as part of urban Kowloon even though it legally remained within the leased New Territories.
What happens after 2047 in Hong Kong?
The Sino-British Joint Declaration established that Hong Kong’s capitalist system and high degree of autonomy under the One Country Two Systems framework would remain unchanged for 50 years after the 1997 handover, meaning until 2047. What happens after 2047 remains an open question. China has indicated that it intends to maintain Hong Kong’s special status, but the specific legal and political arrangements beyond 2047 have not been formally defined.
What is the difference between ceded and leased territory?
Ceded territory is transferred permanently, with full sovereignty passing to the acquiring country under the treaty terms. Leased territory remains under the sovereignty of the original owner, with the lessee granted use of the land for a specified period. Hong Kong Island and Kowloon Peninsula were ceded in perpetuity, while the New Territories was leased for 99 years.
Why did they demolish Kowloon Walled City?
The Kowloon Walled City was demolished in 1993 and 1994 ahead of the 1997 handover. It had existed as a jurisdictional anomaly since 1898, when the convention exempted it from the New Territories lease. Neither Britain nor China fully administered it, leading to decades of unregulated growth and extreme density. Both governments agreed that clearing the site was necessary before the transfer of sovereignty.
Conclusion: Legacy of Different Legal Fates
The story of why the Kowloon Peninsula and the New Territories had different legal fates is ultimately a story about how treaty language creates consequences that echo across centuries. A single word, “ceded” versus “leased,” determined whether Britain owned territory forever or merely borrowed it for a defined period.
The cession of the Kowloon Peninsula under the 1860 Convention of Peking and the lease of the New Territories under the 1898 Convention for the Extension of Hong Kong Territory represented two fundamentally different legal arrangements. But the practical reality of an integrated, interdependent territory meant that this legal distinction could not survive the expiration of the lease.
When the 99-year clock ran out on June 30, 1997, Britain returned everything, not because it was legally required to surrender permanently ceded land, but because Hong Kong had grown into a single organism that could not be cut in half. The Sino-British Joint Declaration and the One Country Two Systems framework resolved the crisis, but the underlying questions about sovereignty, treaty obligations, and the legitimacy of unequal treaties remain relevant today.
As 2026 unfolds, attention increasingly turns to 2047, the year when the 50-year transition period established by the Joint Declaration is set to conclude. The different legal fates that once separated Kowloon from the New Territories have been overtaken by larger questions about Hong Kong’s future relationship with Beijing. But understanding how those fates diverged in the first place remains essential to understanding how Hong Kong arrived at where it stands today.