The mental image most people hold of military conflicts is one of battlefield carnage. This picture is misleading. Most casualties of war are civilians rather than soldiers. For soldiers that do die, they are more likely to have been killed by disease rather than combat. Indeed, before the 20th century, there were almost no military campaigns in which more soldiers were killed by enemy action as opposed to invisible pathogens. Deaths from disease were particularly prominent in Europe’s colonial wars due to medical ignorance and a lack of natural immunity. Philip D. Curtin’s Disease and Empire: The Health of European Troops in the Conquest of Africa provides an unvarnished and academic account of the mortality cost that disease had on Europe’s wars in Africa in the 19th century. Though the book can be dry at times, and there are certainly too many tables (and this is coming from a statistician), it is nevertheless an interesting read that provides a comprehensive and nuanced picture into the history of tropical medicine and military (mis)adventures.

European soldiers and civilians stationed in Africa were usually killed by one of four diseases: malaria, yellow fever, typhoid fever, and gastrointestinal infections. Early medical observers were often confused as to the nature of these diseases, especially before the advent of the germ theory. For example, the malaria virus had different epidemiological patterns depending on which mosquito vector it was transmitted by. While malaria reached its peak during the wet season, this could vary depending on whether the location was near the coast or on the savannah. A lack of data, unexplained variations when data was collected, and confusion around how pathogens spread led most doctors to conclude that malaria was caused by “miasmas”; unknown and unhealthy “vapours” which emerged from the ground. While pattern matching is a useful evolutionary adaption, it has often led to a confused understanding of aetiology throughout history.

Confusion around the mechanism of malarial transmission also reinforced racial stereotypes. It was assumed that “Africans” had a natural immunity to malaria since most locals did not suffer from crippling attacks of virus. Of course, this immunity was conferred through acquired immunity during childhood exposure. This is no different than how Europeans were largely immune to small pox from exposure to farm animals. Britain and France sometimes deployed Caribbean troops of African descent in West Africa on the faulty assumption that they would be immune to tropical diseases. When these troops died, commanders often assumed it was because a lack of “hygiene”, and did not connect the dots to notice the same pattern occurring in European troops. Furthermore, European troops (who survived) their first year of deployment were sent home to protect them from being exposed for too a long a time to the unhealthy “vapours” of the continent. Of course, these were these troops were likely to have acquired partial immunity and were in the best place to stay on. Instead a fresh crop of soldiers was brought in to die at elevated rates.

And the death rate from these tropical diseases could be immense. Of the 59,000 French soldiers sent to crush the Haitian slave revolt from 1791-1803, more than three-quarters died of yellow fever. Data from Curtin’s research shows that 41% of British soldiers serving in Sierra Leone from 1816-37 died every year from fevers alone! In contrast, local African troops had a death date of 0.2% per year. It is therefore hard to overstate the disease risks Europeans experienced in Africa before advancements in tropical medicine. The “white man’s grave” was a seemingly appropriate epithet at the time to describe the continent.

Important medical discoveries made in the early 19th century were, eventually, used to protect most Europeans from deaths of disease. These include Joseph Pelletier’s isolation of emetine to treat amoebic dysentery and the co-discovery with Joseph Caventou of isolating antimalarial alkaloids (e.g. quinine) from cinchona bark. Despite these chemical innovations, the application of European medicine was, at the time, often useless and many times deadly. The thought leader of tropical medicine in France until the 1840s was Francois Broussais who believed that the only way to treat fevers was with a “light diet, heavy bloodletting, and heroic doses of mercurial preparations and opium.” Most French military doctors were trained at the Val-de-Grace hospital where such theories were common. British medical theories at the time were equally as dangerous, and the Brunonian system advocated for similar treatments.

In the early 19th century, the medical practice of blood-letting reached one of its historic peaks. The human body is generally accounted to contain 180 ounces of blood. The ordinary blood donation is about 20 ounces. The usual practice in West Africa was to take 20 to 50 ounces at the outset of a fever, and more thereafter to reach a total that could be more than 100 ounces over a few days - more than half the blood the patient had to begin with. Malaria causes serious anaemia, and its victims need all the blood they can get.

Malaria also causes serious dehydration. Mercurial preparations like calomel are purgatives, which increase the dehydration, but the usual dosage went beyond a simple purge. Calomel was commonly given to bring on a profuse of salivation, which could mean a dosage of 50 to 60 grans a day for four of five days, sometimes reaching as much as 500 grains. At the most extreme, this combination of bleeding and calomel might well cause the death of a healthy person. For patients suffering from dehydration and anaemia, these treatments certainly killed many who would otherwise have survived.

Given the immense risk associated with being stationed in West Africa (both from diseases and doctors), why would any European soldier sign up to be stationed overseas and why would governments send them? While troops knew the “climate” was dangerous in Africa, epidemiology statistics were hardly made available for casual consumption. Furthermore, after the slave trade was banned in 1807, the Royal Navy was mandated to undertake a vigorous campaign to end the transatlantic slave trade. At its peak, the West African Squadron employed a full sixth of the Royal Navy’s fleet. Insightful analysis by Dr. Alexander Bryson published in 1847 was able to show the relationship between the incidence rate and location of malaria. It become understood that as long as European troops remained on deck, they were at almost no risk of malaria, and “any commander who sent boats on shore overnight had to justify the action in writing to the Command-in-Chief of the African Station.”

With fits and starts, European military interventions began to fare slightly better in terms of disease-based deaths. The main mechanisms of improvement were through water filtration and boiling, prophylactic quinine usage, and (by the end of the 19th century) vaccinations. Yet the application and vigour with which these procedures were applied varied by campaign. Sometimes the variation was due to differences in logistical challenges whilst other times it came down to the careless of officers. After Britain invaded Egypt to set up a protectorate in 1882, its stationed troops experienced high rate of mortality from typhoid fever. While a vaccine existed for troops against this disease, there was significant resistance against mandatory vaccination (plus ça change). What is surprising was that resistance to forced inoculation came from within the army.

There is, indeed, no doubt that public opinion would severely condemn any system of compulsory inoculation which though it might obtain some measure of protection for the majority, was admitted to entail upon a certain number of individuals increased liability to disease, suffering, and death. Until further light is throw upon this … it is from every point of view expedient that the present practice of extensive inoculations be suspended.

Inconsistencies in medical education and vestigial beliefs in the Brunonian system led to some surprising variations in the death rates of various campaigns over time. While disease-based deaths tended to decline over time, the pattern was in no way linear. For example, the expedition to destroy Magdala in 1868 to punish the Ethiopian emperor Tewodros II, had a lower disease death rate than another punitive expedition during Third Anglo-Ashanti War 1873–1874 to destory Kumasi, the capital of the Ashanti empire. Furthermore, Wolseley’s failed relief force sent to Khartoum in 1885 had double the disease death rate of the Kumasi campaign. Yet the campaign in Mashonaland in the Second Matabele War in 1896 had the lowest disease death rate for any major British overseas deployment until that time.

Deaths from tropical disease showed and equally erratic pattern for French colonial forces. Although the French almost always faired worse than the British. However, by the outbreak of the first world war, non-wartime casualty rates had drastically dropped. For example, when the French forces invaded Madagascar in 1895 they suffered a disease death rate of 300 per 1000. After occupation, for troops stationed in the barracks, this number had fallen by 90% to 30 per thousand in 1987 and declined a further 85% to 5 per thousand in 1913.

Curtin points out at the time of the Scramble, domestic political audiences were not particularly interested in deaths from disease, and when they were it was only the aggregate amount rather than the death rate. Instead of worrying about whether troops were stationed in epidemiologically dangerous zones, geopolitical considerations triumphed. For example, concerns about a Russian invasion of India from the north almost led to a war between Britain and Russia in 1885 after the Panjeh incident in Afghanistan. Why were British troops being wasted in Africa when they could be defending the Jewel in the Crown? Never mind that the disease death rate from the Second Anglo-Afghan War was significant. Yet after the Battle of Omdurman in 1898 British popular opinion swung to the view that the Egyptian garrison was actually a jolly good thing, irrespective of the typhoid death rate.

The Boer War at the turn of the century brought to public attention the appalling consequences of poor medical planning and hygiene. Unlike previous colonial wars, this one was fought against ethnically European troops armed with modern rifles and training. Though the Boer republics never had more than 50,000 troops in the field, the British had to deploy more than half-a-million men to subdue the guerilla forces. The overwhelming majority of British troops died of disease rather than in combat.

The epidemics at Bloemfontein and Ladysmith, plus the death in the concentration camps - together with the spread of information about the progress of scientific medicine in generally - brought home the lesson that the lack of pure water and sanitation cost lives. The publicity was among the influences that enabled RAMC to reform the practice of military medicine as never before. This is, in short, another variant of the proposition that the conquest of Africa did far more to bring about the improvement of the tropical medicine than that the improvements in tropical medicine caused the conquest of Africa.

Curtain’s conclusion of the book elegantly summarizes the reasons why deaths from disease were not taken more seriously at the time.

The more significant question is not whether tropical medicine caused imperialism, but why European expeditionary armies profited so little from the new medical knowledge? In 1874, after all, orders for the march on Kumasi called for compulsory prophylactic quinine and for all drinking water to be boiled and filtered. It wasn’t done perfectly, of course, but most later expeditions did it still less perfectly.

Part of the explanation is ordinary inefficiency combined with an unawareness of hygiene at all levels of European society. Even today, otherwise intelligent and responsible people can be careless about routine health precautions. A century ago, several sets of elaborate rules for tropical hygiene were available, but even trained physicians took them less seriously than they do today. The public seems to have regarded them no more seriously than the danger of walking under a ladder or planning activities on Friday the thirteenth.

For that matter, medical education underemphasized hygiene in favor of the clinical treatment of the patients who applied for help. Public health was just beginning to enter medical thinking. Curiously enough, the beginning of public health education on any scale was in the training of army doctors at Netley or Val-le-Grace, or equivalent institutions else-where in Europe, America, and Japan, even through the ultimate objective of military medicine had to be tuned to the achievement of military victory. Many of the most significant advances in preventive medicine, and not only for the tropics, were made by army doctors or others on overseas assignments whose work involved research as well as clinical practice.

Military officers had another kind of training. They were selected for qualities such as dash, bravery, and the willingness to take risks that would win battles. Military reformers in the late nineteenth century, like Sir Garnet Wolseley, were concerned that new technology required new attitudes and a new kinds of military education, and this included preventive medicine, though still subbordinate to the main task of victory in the field. Other military leaders simply neglected the measures contemporaneous military medicine could provide, with a peak of irresponsibility in the French campaign in Madagascar in 1895.

Politicians were schooled in still another set of attitudes — to respond to the weight of public opinion within the ruling class of their respective countries, and to win elections. If their generals won battles, politicians were anxious to get the credit. If generals lost wars, politicians sometime lost office, as Gladstone did after Wolseley failed to “rescue” Gordon in 1885. If the soldiers suffered from disease, it rarely came to public notice; and, if it did, it was easy to blame the Medical Department, not the commanding general. Even in the British hospital scandals of 1882 and 1900, critics came down on failure to care adequately for sick soldiers, not on the failure to prevent them from getting sick in the first place.

In the half-century before the First World War, furthermore, the European public forum was concerned with other issues. The 1880s and 1890s was the period of frenzied international competition for empire overseas, in which the conquest of Africa was only one theater of operations. The technological stars were the new weapons that brought cheap victory against those who still had no access to them - until the Anglo-Boer War showed what would happen if others were armed in the same way.

Even more, these campaigns took place in a European mood of increasingly emotional nationalism. This political mood was part of the European social pathology that was to permit the slaughter of 1914-18 in the European war. Given the tolerance for the destructiveness of modern warfare, it is small wonder that the European public or European politicians only a generation earlier cared so little about the death from disease of a few thousand soldiers on campaign in distant Africa.