IN 1918, misfortune befell the 22-year-old poet Suryakant Tripathi, better known as Nirala or “the strange one.” “I travelled to the riverbank in Dalmau and waited,” he wrote in his memoir, A Life Misspent. “The Ganga was swollen with dead bodies. At my in-laws’ house, I learned that my wife had passed away.” Many other members of Nirala’s family died too. There was not enough wood to cremate them. “This was the strangest time in my life,” he recalled later. “My family disappeared in the blink of an eye. All our sharecroppers and labourers died, the four who worked for my cousin, as well as the two who worked for me. My cousin’s eldest son was fifteen years old, my young daughter a year old. In whichever direction I turned, I saw darkness.” These deaths were not just a coincidence of personal tragedies visited upon the poet, they were connected: “The newspapers had informed us about the ravages of the epidemic,” Nirala wrote.

The epidemic was actually a pandemic that affected not just the subcontinent but the entire globe. The disease, influenza, claimed between 50 and 100 million lives worldwide—possibly more than both world wars combined—and India was the country that bore the greatest burden of death. Though other countries lost a higher fraction of their populations—Western Samoa (now Samoa) lost 22 percent, for example, compared to 6 percent in India—because of the larger size of the Indian population, that 6 percent translated into a staggering slew of death. Between 1918 and 1920, an estimated 18 million Indians lost their lives to influenza or its complications, making India the focal point of the disaster in terms of mortality. Asia as a whole experienced some of the highest flu-related death rates in those years, but the story of how the disease ravaged the continent is relatively unknown. The 1918 flu pandemic has been called the “forgotten” pandemic, and ironically the continent that seems to have forgotten it most thoroughly is the one that bore the brunt of it.

As Stalin is supposed to have observed, a single death is a tragedy, a million deaths is a statistic. Perhaps that is why we turn to a poet to tell us what it felt like to live through that terrible moment—to translate the sterile numbers into human experience. Nirala is now recognised as a leading figure in modern Hindi literature, and there is no doubt that the 1918 flu pandemic left a deep impression on him, as it did on many Indians. In fact, as I argue in my book on the Spanish flu—as the pandemic was sometimes known, though there was nothing particularly Spanish about it—there is a good case to be made that the devastation wrought by the disease exacerbated social tensions in India, contributing to an eruption of violence and significantly strengthening the independence movement. To understand why, it is necessary to understand the nature of flu pandemics in general, and of the 1918 flu pandemic in particular.

THE INFLUENZA VIRUS INFECTS many animals besides humans. It is notorious for the ease with which it mutates, so that occasionally a novel strain arises that can cross the species barrier from one of those animals—often a bird—to a human. If that strain acquires the capacity, again through mutation, to pass easily between human beings, then it may trigger a pandemic. That is because no living person has been exposed to it previously, meaning that the human population as a whole has very little immunity to it. Over time, however, the new strain moderates its virulence in order to live in a more harmonious equilibrium with its human host. It does not do this consciously, but through a process of natural selection, since viral mutations that keep the host alive for longer—so that he or she can move around and infect other hosts—allow the virus to continue reproducing and generating more copies of itself. The pandemic recedes, but the strain that caused it continues to circulate in humans as a seasonal flu.

Flu pandemics happen, therefore, whether we like it or not, and there have been an estimated 15 of them in the last 500 years. But another thing researchers have discovered about them is that their severity is in part determined by the human population into which they emerge. Of the five flu pandemics humanity has endured since the 1890s, for example, none—with the exception of the 1918 episode—has killed more than about two million people. The one in 1918 was therefore an anomaly, and researchers think that has a lot to do with the state of the world at the time—notably its state of war.

1918 was the last year of the First World War, a war that was fought in fairly circumscribed theatres in Europe and the Middle East, but that made itself felt much further afield. Indian men were enlisted into the British Army, for example, and Indian-grown food supplied the British war effort. These factors helped shape the pandemic and the Indian experience of it, as did the difficult economic situation in the country, and the independence movement.

Indian men were enlisted into the British Army and Indian-grown food supplied the British war effort. The Print Collector/ Getty Images

Hunger weakens the immune system, and hunger was rife in many regions of the world in 1918, partly due to disrupted supply lines. Other infectious diseases, such as tuberculosis and typhus, had made inroads into human populations, capitalising on the disruption wrought by war and rendering their victims more vulnerable than usual to a new respiratory infection. Large numbers of people, both troops and refugees, were on the move, providing the ideal vehicle for disseminating that infection. Meanwhile, the very lack of mobility of one group may have helped brew a particularly lethal germ that year, or at least kept it lethal for longer. Once the virus reached the Western Front—the 16-kilometre-wide system of trenches that gashed France from the Belgian to the Swiss border—it encountered large numbers of young men who, packed into those trenches, did not go anywhere for weeks or months. Paul Ewald, an evolutionary biologist at the University of Louisville in Kentucky, has argued that under such exceptional conditions, the evolutionary pressure on the virus to moderate its virulence may have been relieved. It became the mobile one in the host-virus relationship, and it raced through the trenches, killing as it went.

Flu pandemics have a characteristic structure, engulfing the world in waves. The first wave, sometimes called the herald wave, is often quite mild, resembling a seasonal flu. This tends to be followed by a more deadly second wave, and in some cases, subsequent waves of varying severity. The flu pandemic of 1918, though unusually virulent, was no different in this respect. There was a mild herald wave in the northern-hemisphere spring of 1918, a much more lethal second wave in the latter part of that year, and a final recrudescence in the early months of 1919, which was intermediate in severity between the other two. The pattern was repeated in the southern hemisphere, but it was staggered in time with respect to the north, meaning that the waves tended to strike later there. The pandemic is conventionally considered to have been over by March 1920, although earlier this year, the epidemiologist Dennis Shanks and his colleagues at the University of Queensland in Brisbane reported that it dragged on in the Pacific islands for another year, with cases still being reported in New Caledonia in July 1921.

The 1918 flu first appeared in India in June of that year, entering via the city of Bombay. From there it spread to Punjab and the United Provinces (present-day Uttar Pradesh) in July and August, before receding.When the second wave erupted in late September, it was barely recognisable as the same disease. Researchers believe that the virus may have undergone a critical mutation between the spring and the summer—possibly in those trenches of the Western Front—which rendered it far more dangerous. This wave peaked in October and receded in December, and there was a third wave in early 1919. As the medical historian Mridula Ramanna, then at the University of Mumbai, observed in 1998 when she summarised the state of knowledge on the Indian flu experience, “Hardly any part of the country escaped the epidemic… whether it was the hill tops of Simla, or the few healthy sanitary quarters of modern cities, like Bombay, or the slums of Ahmedabad, or isolated villages.” It has since become clear, however, that it did not affect all parts of the country equally.

ABOUT TEN YEARS AGO, when Indian-born health economist Siddharth Chandra took up the directorship of the Asian Studies Center at Michigan State University in East Lansing, he had barely given any thought to the 1918 flu pandemic. He was searching for data that would speak to an entirely different question—how governments have historically manipulated access to opium and other addictive drugs to control populations and raise revenue—and his focus was the Dutch East Indies, or Indonesia, in the early-twentieth century. Realising that Indian population data for the same period was more detailed, he shifted his focus. Soon he noticed something odd: between the censuses carried out by the colonial authorities in 1911 and 1921, the Indian population had not grown as fast as it might have been expected to. He suspected that the reason was flu.

“At that point there was very little research on the 1918 flu in Asia, even though Asia is where 60 percent of the world’s population currently lives,” Chandra told me. “Most of the research had been carried out in wealthy countries.” He decided to correct that oversight, and his first step was to procure a copy of the 1918 annual report of the sanitary commissioner of India. “It is a page turner,” he said, “I stayed up one whole night and read it from cover to cover.” It wasn’t just the Ganga that had been clogged with corpses, he discovered, but rivers all across India. The descriptions were vivid and shocking, and among them were some hard numbers.

In 1951, the famous American demographer Kingsley Davis made a rough calculation of the number of Indian lives lost to the 1918 pandemic, based on available census data, and had arrived at a figure of around 20 million. But Davis had assumed that the population had been growing at the same rate before and after the pandemic. “Nowadays,” Chandra said, “we know that assumption was not justified. In fact, it was growing much more slowly before the pandemic than after.”

Correcting for that discrepancy, Chandra and his colleagues reported in 2012 that approximately 14 million Indians had died in the pandemic. Their estimate only applied to those parts of India—which in 1918 included Pakistan and Bangladesh—that were under direct British rule, and excluded the princely states where the British ruled by proxy. Around 80 percent of the Indian population was under direct rule, and allowing for losses in the princely states, Chandra claimed that 18 million was a reasonable estimate for the death toll in India as a whole. At roughly 6 percent of the population, this may not have been the highest national death rate, but it was still far higher than the 1 percent or lower experienced by many wealthy, developed nations.

Chandra’s team then turned to mapping the epidemic’s spread in India, and now they discovered something intriguing. When the second wave of the flu arrived in Bombay in September 1918, almost certainly with an infected troopship returning from Europe, the data revealed a big spike in mortality in the Bombay Presidency, implying that the epidemic passed through this western province rapidly and lethally. But as it radiated out to the north and east, the spike seemed to lose height and gain width, indicating that the disease was moving more slowly and killing a smaller proportion of those it infected. By the time it reached Calcutta in the east, it was much less malign than it had been in Bombay.

According to Chandra, there are three current theories to explain this effect. The first is that different climatic conditions in different parts of the country might have shaped the epidemic. The second is that, seeing the epidemic coming, people living in the east might have adapted their behaviour to protect themselves—by staying indoors, for example—something that those in the west, lacking warning, had been unable to do. But the third theory seemed to appeal to him the most, even though, as he pointed out, it remains to be tested: “What you could be seeing, as the epidemic sweeps the country, is the virus in the act of evolving—of becoming more moderate.”

There are also some patterns in the data that appear to buck the broader trends. For example, although the second wave first appeared in the city of Bombay—a major garrison in the north at the time—it erupted soon after in Madras on the southeast coast. Madras was also a garrison town, and it is not clear whether it received the flu from Bombay, with which it was connected by rail, or via a troopship. Puri, a sacred Hindu site on the east coast, also saw an early spike—having no doubt received the disease with pilgrims who came from the west. Uttar Pradesh, then as now, one of the most populous Indian states, lost up to three million inhabitants alone, but the state’s geography and geology influenced the path the disease took across it. This state, where both Nirala and the popular writer Munshi Premchand were living at the time, is bisected by the Ganga. “In general, areas to the north of the river, closer to the mountains, received the flu later than the ones to the south, where all the major railway lines ran,” Chandra said.

Thus terrain and humans’ modification of it shaped the epidemic in India, as elsewhere. Railway lines ensured the efficient spread of the virus, and cities—both because they tended to be better connected by those lines, and because they were more densely inhabited—were, in general, worse affected than rural areas. But social and economic factors left their mark too. The colonial authorities’ public-health provision was under-powered at the best of times, and many doctors were away at the front. Western medicine was, in any case, poorly equipped to deal with a severe influenza in 1918.

Virus was a fairly new concept at that time, and most doctors believed the disease to be bacterial in origin. Even in the wealthiest countries, they had no effective vaccine, no antiviral drugs and no antibiotics—which might have been useful in treating the secondary bacterial infections that killed most of the flu’s victims—since these were yet to be invented. They generally fell back on the so-called wonder drug, aspirin, if it was available, and then in desperation on more dubious and colourful treatments. Western medicine was not yet widely accepted in India, and most people turned to Ayurveda when ill. It is not clear which of these was more effective against flu, if either had any effect at all besides the sometimes adverse effects of the treatment. The only thing that did make a demonstrable difference, sometimes between life and death, was careful nursing. But nursing was in its infancy in India.

“The epidemic struck India at a time when it was least prepared for it,” Ramanna noted in 1998. According to Sekhar Bandyopadhyay, a historian at the University of Wellington in New Zealand, there had been near-famine conditions in many parts of the country in the early-twentieth century, and a bad situation had been made worse by the failure of the monsoon in 1918. By September, when the second wave erupted, the country was in the grip of a severe drought. “People begged water,” one American missionary reported. “They fought each other to get water; they stole water.”

The first annual crop was due to be harvested, and the second sown, but with so many sick there was no manpower to complete these tasks. As Bandyopadhyay explained, the colonial authorities made no allowance for the domestic shortfall, continuing to export wheat and rice to feed the troops well into the autumn. Inflation rocketed, especially where food was concerned. “The price index at the national level rose from 147 in 1914 to 281 in 1920, which for any society would cause havoc,” he said. By October 1918, when the second wave of the epidemic peaked, people were jumping on moving freight trains to steal grain, and famished refugees were flooding into Bombay.

“This was a period that was marked by strong feelings of discontent in every quarter,” Bandyopadhyay said. But if the discontent was in every quarter, the flu hit some quarters harder than others. Across the globe, this flu targeted not only the oldest and the youngest—as in a normal flu season—but also those aged between 20 and 40, especially men. Women seemed to be afforded some protection, for reasons that are not clear—unless they were pregnant, in which case they suffered miscarriages and died in shockingly high numbers. In some parts of the world, the gender bias was reversed in certain age groups, but in India, startlingly, it was reversed in every age group. Indian women and girls, in other words, were uniformly more vulnerable than Indian men and boys. Again, the reasons are not clear, though among the explanations that have been proposed is that men had a greater claim to a family’s resources, particularly when those resources were scarce, while women were more likely to nurse the sick. Females may, therefore, have been more vulnerable, being hungrier and more exposed to the virus.

Another universal pattern, that was remarked upon at the time, was that the poor and workers suffered worse from the flu, in general, than the well-off. This was not because they were constitutionally inferior, as eugenicists liked to claim, but because they were more likely to be hungry, to have an underlying disease and to be housed in crowded and unhealthy accommodation, and less likely to have access to medical or nursing care. Social exclusion played its part. In 2012, the British historian David Hardiman reported that the remote, forested region of the Dangs in Gujarat lost a higher proportion of its population than most Indian cities, thereby flouting the “rural advantage” rule. The reason, he suggested, was that the Dangs were home to adivasis, who were looked down upon by both the British and other Indians as backward jungle tribes.

As soon as the pandemic had passed, the sanitary commissioner for India recognised that it had been a “national calamity,” but even while it was raging, the government realised that it could not cope, and it appealed for help. Help duly came, mostly from organisations such as the Gujarat Sabha, which had close ties to the national independence movement. Many were active in social reform, meaning they were well placed to mobilise dozens of local caste and community organisations. In the Surat district of Gujarat, for example, two young brothers and freedom fighters named Kalyanji and Kunvarji Mehta stepped into the breach. Their flu-relief work brought them into contact both with the adivasis and with other freedom fighters, notably Dayalji Desai, as well as strengthened their ties with the national independence movement that funded their efforts.They are conservatively estimated to have helped 10,000 people in Surat—including Muslims, Christians, tribespeople and Dalits.

By 1918, Gandhi was being seen in intellectual circles as a future leader of the nation, but he lacked grass-roots support. That spring, in his native state of Gujarat, he had organised two of his first satyagrahas, but these were followed by thousands of people, not hundreds of thousands. When the flu returned that autumn, he was struck down, as were other leading members of the independence movement who shared his ashram, notably Gangabehn Majmundar, the formidable spinning teacher, and Shankarlal Parikh, who had helped organise one of those early satyagrahas. Gandhi was too feverish to speak or read. He could not shake a sense of doom. “All interest in living had ceased,” he wrote later, in his autobiography.

In November, the armistice was signed, bringing the war in Europe to an end. Gandhi was still sick. Retrospective diagnosis is notoriously unreliable, but it is possible that his illness dragged on for so long because he developed pneumonia as a result of a secondary bacterial infection of his lungs. Hard on the heels of the armistice came the publication of the Rowlatt Report, in which Justice Sidney Rowlatt of the viceroy’s legislative council recommended the extension of martial law into peacetime. Throughout the war, civil liberties had been suspended, meaning that Indians could be arrested without charge and tried without a jury. Rowlatt found that levels of sedition and terrorism justified maintaining that situation. Indians had expected more freedom; they got more repression. It was one provocation too many. “From 1918 on there was social and political unrest all over India,” Bandyopadhyay said, “and the social background of that unrest is one of epidemic and famine.”

Rowlatt’s bill passed into law in February 1919. Gandhi was still weak: “I could not at that time sufficiently raise my voice at meetings. The incapacity to address meetings standing still abides. My entire frame would shake, and heavy throbbing would start on an attempt to speak standing for any length of time.” But there was no question of him not rising to the occasion. To channel the disenchantment against what he called “those black acts,” he called for satyagraha. Dayalji Desai and Kalyanji Mehta answered his call in Surat. These two, whom caste barriers would normally have kept apart, were now united in the fight for self-rule under the nickname “Dalu-Kalu.”

The satyagraha against the Rowlatt Act culminated in the tragic events of 13 April 1919, when General Dyer ordered his troops to fire into an unarmed crowd in Amritsar’s Jallianwala Bagh garden, killing more than a thousand people. Vithalbhai Jhaveri/Dinodia Photo

The satyagraha against the Rowlatt Act culminated in the tragic events of 13 April 1919, when Brigadier General Reginald Dyer ordered his troops to fire into an unarmed crowd in Amritsar’s Jallianwala Bagh garden, killing more than a thousand people. In 1920, a special session of the Indian National Congress party was held in Calcutta. The Mehta brothers were among those who accompanied Gandhi to it, in a special train from Bombay. When he promised self-rule within a year if Congress backed his call for nationwide satyagraha, Kunvarji Mehta was inspired. He returned to Gujarat and delivered five towns to the cause. Half-a-million workers are estimated to have gone on strike in 1921, and many more in the years that followed. Gandhi’s promise turned out to be premature, but by 1921, thanks in no small part to the freedom fighters who had brought relief to millions of ordinary Indians, he had grass-roots support.

Ten days after the terrible events in Amritsar, an editorial appeared in the pro-independence journal Young India, that reflected the nation’s darkening mood. Entitled “Public Health,” it expressed the feeling on the streets of Bombay that a government that allowed six million to die of influenza—the contemporary Indian estimate of its loss—“like rats without succour,” would not mind if a few more died by the bullet. In 1921, Nirala gave vent to that mood in his own way. He wrote a poem entitled Beggar, which contained the following lines:

When their lips shrivel up from starving what recompense from the generous Lord of destinies? Well, they can drink their tears.

Nirala had learnt that the world was cruel and there was no place in it for sentimentality. His fellow writer and flu survivor, Munshi Premchand, would go on to make his name describing the harsh realities of life for ordinary country folk. His tales are full of uncorrected and sometimes even unnoticed injustices, and he became the self-styled “chronicler of village life” around 1918, when the flu was ripping through the United Provinces.

In both art and politics, therefore, the pandemic left its trace, but it also shaped India in a more profound way. When Chandra was calculating how many Indians died in the disaster, he discovered that the population grew much more slowly before it than after. Drought, famine and, more generally, the high price of war, could have led to to the earlier slowdown, but perhaps something accelerated population growth in the 1920s too. Could that factor have been the 1918 flu pandemic?

It is not out of the question. Though the country experienced a 30-percent reduction in births in 1919, fertility not only returned to pre-flu levels starting in 1920, it exceeded them. This baby boom was seen in other parts of the world, too, and it has often been put down to the wave of new conceptions that followed the return of the men from the front. But another theory researchers are currently exploring is that, by purging the less-than-fit—those already suffering from tuberculosis, malaria and other diseases, for example—the flu left behind a smaller but healthier population. By virtue of their robust health, those survivors would have been capable of reproducing at higher rates, and this might also have contributed to the so-called demographic revolution that took off in India in the 1920s.

Both individual tragedy and collective resilience shaped the Indian story in those years, therefore, but the 1918 influenza pandemic taught us many other lessons too—not least, that no nation is an island where contagious pathogens are concerned. We know that another flu pandemic is inevitable, and scientists and public health experts are busy preparing us for it—though they are not yet able to predict when or where it will emerge, or how bad it will be. Perhaps the most important lesson that 1918 taught us is that a pandemic is both a biological and a social phenomenon, with both biological and social consequences, and if we ignore one of those dimensions at the expense of the other, we do so at our peril.