The Great Hanoi Rat Massacre (Vietnamese: Đại thảm sát chuột ở Hà Nội; chữ Nôm: 大慘殺𤝞於河內; French: Massacre des rats de Hanoï) occurred in 1902, in Hanoi, Tonkin, French Indochina (present day Hanoi, Vietnam), when the French government authorities attempted to control the rat population of the city by hunting them down. As they felt that they were making insufficient progress, and due to labour strikes, they created a bounty programme that paid a reward of 1¢ for each rat killed. To collect the bounty, people would need to provide the severed tail of a rat. Colonial officials, however, began noticing rats in Hanoi with no tails. The Vietnamese rat catchers would capture rats, sever their tails, then release them back into the sewers so that they could produce more rats.
The Great Hanoi Rat Massacre happened in the middle of a global plague pandemic only a few years after Swiss-French physician and bacteriologist Alexandre Yersin linked the spread of the pandemic to rodents.
Today, the events are often used as an example of a perverse incentive, commonly referred to as the cobra effect. The modern discoverer of this event, American historian Michael G. Vann argues that the cobra example from the British Raj cannot be proven, but that the rats in the Vietnam case can be proven, so the term should be changed to the Rat Effect.
Background
French plans for Hanoi
France formally assumed control of Hanoi in 1882, occupying the city after the failure of the Treaty of Saigon. However, the region of Tonkin was not fully pacified until as late as 1896. The French colonised Eastern Indochina (present day Vietnam, Cambodia, and Laos) in several stages to gain backdoor access to the wealth of China through its market, specifically the French sought a river route to the Chinese province of Yunnan, which at the time was imagined as "El Dorado with silk instead of gold".
Prior to the establishment of the French protectorate of Tonkin, the city of Hanoi was a collection of 36 streets, each of these streets was devoted to a specific craft as well as several temples and pagodas spread around the settlement. Furthermore, the city of Hanoi also possessed a citadel and fort, these were ironically constructed in 1803 (the year after the Nguyễn dynasty was established by the Gia Long Emperor) with the assistance of French military engineers that were trained in the Vauban tradition of fortification. However, the French viewed Hanoi as a dirty, squalid, ramshackle collection of villages. So they sought to transform it into a French-style city worthy of being the seat of one of the colonial possessions of the French Empire. This process began with the arrival of French administrators in the 1880s, namely Paul Bert in 1886, and set off the Gallicisation of the city. Large areas of Hanoi, including most of the old citadel as well many temples, were demolished to make way for the new French-style buildings that would become the core of the new city. Most notable among these new constructions were St. Joseph's Cathedral and the Lanessan Hospital.
In 1897, Paul Doumer had been appointed Governor-General of French Indochina after he was briefly the French Minister of Finance (1895–1896) when he tried without success to introduce an income tax. Under his leadership, the old Hanoi would be transformed into a completely different city and the transformation went into overdrive. As Doumer planned on making Hanoi the new capital of the Union of Indochina he insisted that it should also look the part. To fulfil this plan, a new palace for the residence of the Governor-General of French Indochina was constructed (which serves today as Vietnam's Presidential Palace). Large parts of Hanoi were cleared to make room for the new French-style inner city that was filled with broad tree-lined boulevards, colonial-style villas, and well-tended gardens. This new area would be known as the "French Quarter" (Quartier Européen / Khu phố Pháp, today's Ba Đình District), as some visitors would describe it as "a slice of Paris on the other side of the world". This area of the city sharply contrasted the cramped, narrow, and chaotic "Native Quarter" (Quartier indigène), where both the indigenous Annamese people and Han Chinese people resided.
In the year 1902, the capital city of French Indochina was moved from Saigon, Cochinchina (present day Ho Chi Minh City) to Hanoi, Tonkin and it remained so until 1945. When Paul Doumer arrived in Hanoi, he launched several major infrastructure projects, such as the Paul Doumer Bridge (now called the Long Biên Bridge), which spanned the 1,700-meter (5,600 ft) width of the Red River, and the Grand Palais d’Expositions which built for the Hanoi Exhibition in 1903. These actions were enacted to make Hanoi a showcase for France's civilising mission in Indochina and to provide the city with the very first electricity network in Asia.
French public health mission and the sewage system
Among the large projects, ordered by Paul Doumer, was the construction of a massive underground sewage system that would serve both as a symbol of French modernity and keep the "French Quarter" clear of any human waste. As toilets were seen as "a sign of civilisation" Doumer wanted there to be flushable toilets in every French palace. By the time of Paul Doumer's departure in March 1902, over 19 kilometers of sewers had been built underneath Hanoi, the largest concentration of which lay beneath the "French Quarter". A smaller section of the sewage system also lay underneath the "Indigenous Quarter" of the city. The new sewer system did help fight Cholera, a disease brought to Hanoi by the French expeditionary forces coming from Algeria.
This large new sewage system also brought with it a new unforeseen problem from the French, rats. In the sewers, rats found no natural predators and if they would get hungry they could easily penetrate directly into the most luxurious apartments in the city through the "highway" hidden deep beneath human footsteps. This caused major concerns for the French both for hygienic reasons and an outbreak of the Bubonic Plague (or the "Black Death"). Just a few years earlier in 1894, the famous Alexandre Yersin discovered the Yersinia pestis bacteria that caused the disease and his colleague Paul-Louis Simond linked it to fleas found on rodents. Because of the new knowledge about how rats caused the Bubonic Plague, the French colonists became very concerned with the situation and quickly wanted to remedy it.
"If industrialisation changed the world for human beings, it also created new opportunities for their furry neighbours. Expanding cities and long-distance trade networks offered rats new habitats and new ways to travel distances far greater than they could with just their stubby little legs. As with humans, these technological changes resulted in a demographic explosion. I'm not sure if we breed like rats or they breed like people. It is impossible to know the exact rat population, but scientific estimates indicate that these rodents currently outnumber human beings by several billion. I find it fascinating that as humans went through an unprecedented population boom from 1800 to the present, rats, which most people consider a pest, increased in number as a direct consequence of human actions."
— Michael G. Vann at "The Great Hanoi Rat Hunt: A Conversation with Michael G. Vann" (20 August 2020) - The Made in China Journal.
Contemporary pandemic
The third plague pandemic started in 1855 in Yunnan, China during the Qing dynasty period. This episode of bubonic plague spread to all inhabited continents, and ultimately led to more than 12 million deaths in India and China (and perhaps over 15 million worldwide), with at least 10 million killed in India alone, making it one of the deadliest pandemics in history.
In 1898 Paul-Louis Simond was in the city of Karachi, Sind, India where, despite limited resources, he was able to demonstrate that fleas transmit the bacterium Yersinia pestis, the agent causing bubonic plague, from rat to rat, and from rat to human.
The third plague pandemic happened at the same time as the French renovation of Hanoi. From Yunnan it spread to Guangzhou and then to Hong Kong. The Bubonic plague then spread from Hong Kong to the British Raj. The United States military brought it to Manila during their invasion of the Philippines at the Asian theatre of the Spanish–American War. In 1899 it struck the Republic of Hawaii, where in Honolulu (its capital city) the authorities chose to burn down its Chinatown. Before the Bubonic plague hit the American city of San Francisco its municipal authorities decided to enact a quarantine policy for its Chinatown. During the quarantine the municipal authorities discussed enacting a "Honolulu Solution" to prevent the disease from affecting the rest of the city.
The global situation became serious for Hanoi when French residents reported an infestation of rats in the French Quarter. It seems that brown rats in Hanoi arrived on ships and trains that came from China where the pandemic started. This invasive species of rats quickly discovered that the new sewers were an ideal ecosystem and rapidly took over Hanoi's urban infrastructure, with reports coming out that people had spotted rats climbing up the outflow pipes and later even out of the toilets in French houses. The realisation that these might be plague-carrying rats created a panic among health officials leading to their response to attempt to eradicate the rat infestation before the city would succumb to the pandemic.
Social environment and French government policy at the time
The demand for silk waned as the French completed their railway between Kunming, Yunnan and Hanoi, but this opened up a new market for opium. Yunnan was a major producer of opium and the French wanted to use the line of Yunnan to Haiphong to supply the French Concession in Shanghai. Paul Doumer turned French Indochina into a narco-state and uplifted French Indochina's revenue from being consistently making losses to being profitable. This also made the colony economically interdependent with the Chinese Empire. This turned Chinese goods, Chinese merchants, and Chinese labourers into "the life blood" of the Union of Indochina. Because of the colony's dependence on the Chinese market, French colonists commonly claimed that neither they nor the natives were in charge of it as the Chinese effectively controlled it, while others referred to the Chinese negatively as "the Jews of Asia".
During Napoleon III's Second Empire, France was an authoritarian technocratic state, but after the Second Empire fell, the new Third Republic embraced Progressivism and the technocrats who had a free rein during the Empire were frustrated by the new democratic constraints placed upon them. Many of these technocrats were drawn by French colonial empire, where they could engage in widespread social experiments without the fear of opposition or negative public opinion as they could use the military to enforce their policies. In Hanoi, this translated to a complete renewal of the city based on French modernity.
The French Quartier Européen was located right next to the old 36 streets of Hanoi, in the perspective of the French, the 36 streets were an old and dirty place. The Native Quarter had many lakes and ponds, the roads were mostly dirt roads, when it rained it became muddy, and the houses were shabby with mostly thatched roofs. By contrast, the Quartier Européen area had wide roads, green trees, and white spacious villas. Roughly 90% of the population of Hanoi lived in the Old Quarter which made up only a third of its surface area, while the Quartier Européen and an administrative and military district to the west held only 10% of the city's population and made up the other two-thirds of the city. This resulted in Hanoi being an examplar "colonial dual city" where the colonial elites enjoyed spacious luxurious lifestyles compared to the colonised natives who were all cramped into pre-colonial slums.
During the early period of French rule in the Union of Indochina, colonial officials knew almost nothing about the tropical diseases they would encounter. When epidemics of smallpox, diarrhea, dengue fever, syphilis, etc. would break out, they could do nothing but erect barriers between them and the natives. The French regarded their colonial empire as a Mission Civilisatrice and justified the urban renovations of Hanoi as an act to "combat disease".
During the 1890s, Hanoi was being equipped with modern sewers using the latest technology and the city received its own freshwater system, access to these resources was quite strictly divided between racial lines as the system only served the White parts of town while very little Asians actually having access to the benefits of the city's new urban infrastructure. While the newly built French-style villas contained both running water systems and modern flush toilets, most of the Vietnamese and Chinese residents of the city who resided in the Old Quarter had to collect water from public fountains. The human waste, commonly found in these public fountains, was removed by pre-dawn night-soil collectors. Rather than having any proper sewers, the Old Quarter only contained gutter drains.