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.
The Blitz
London had nine million people – a fifth of the British population – living in an area of , which was difficult to defend because of its size. Based on experience with German strategic bombing during World War I against the United Kingdom, the British government estimated after the First World War that 50 casualties – with about one third killed – would result for every tonne of bombs dropped on London. The estimate of tonnes of bombs an enemy could drop per day grew as aircraft technology advanced, from 75 in 1922, to 150 in 1934, to 644 in 1937. That year the Committee on Imperial Defence estimated that an attack of 60 days would result in 600,000 dead and 1.2 million wounded. News reports of the Spanish Civil War, such as the bombing of Barcelona, supported the 50-casualties-per-tonne estimate. By 1938, experts generally expected that Germany would attempt to drop as much as 3,500 tonnes in the first 24 hours of war and average 700 tonnes a day for several weeks. In addition to high-explosive and incendiary bombs, the enemy would possibly use poison gas and even bacteriological warfare, all with a high degree of accuracy. In 1939 military theorist Basil Liddell-Hart predicted that 250,000 deaths and injuries in Britain could occur in the first week of war. London hospitals prepared for 300,000 casualties in the first week of war.