Syndemic
The worst of the 20th century influenza pandemics was the 1918 pandemic, where between 20-40 percent of the world’s population became ill between 40-100 million people died. More people died of the so-called Spanish flu (caused by the H1N1 viral strain) pandemic in the single year of 1918 than during all four-years of the Black Death. The pandemic had devastating effects as disease spread along trade and shipping routes and other corridors of human movement until it had circled the globe. InIndia, the mortality rate reached 50 per 1,000 population. Arriving during the closing phase of the World War I, the pandemic impacted mobilized national armies. Half of U.S. soldiers who died in the "Great War," for example, were victims of influenza. It is estimated that almost ¾ of a million Americans died during the pandemic. In part, the death toll during the pandemic was caused by viral pneumonia characterized by extensive bleeding in the lungs resulting in suffocation. Many victims died within 48 hours of the appearance of the first symptom. It was not uncommon for people who appeared to be quite healthy in the morning to have died by sunset. Among those who survived the first several days, however, many died of secondary bacterial pneumonia. It has been argued that countless numbers of those who expired quickly from the disease were co-infected with tuberculosis, which would explain the notable plummet in TB cases after 1918.
Deadliest single days of World War I
The First World War was fought on many fronts around the world from the battlefields of Europe to the far-flung colonies in the Pacific and Africa. While it is most famous for the trench combat stalemate that existed on Europe's Western Front, in other theatres of combat the fighting was mobile and often involved set-piece battles and cavalry charges. The Eastern Front often took thousands of casualties a day during the big offensive pushes but it was the West that saw the most concentrated slaughter. It was in the west that the newly industrialized world powers could focus their end products on the military-industrial complex. The deadliest day of the war was during the opening day of the conflict. The Imperial German war council had initiated the Schlieffen Plan which involved multiple armies flooding through the borders of Belgium and France. On August 22, 1914, during the Battle of the Frontiers five separate French armies engaged the German invaders independently of each other. Across all those battlefields, on that single day, 27,000 French soldiers lost their lives protecting their country.