World War I casualties
Casualty statistics for World War I vary to a great extent; estimates of total deaths range from 9 million to over 15 million. Military casualties reported in official sources list deaths due to all causes, including an estimated 7 to 8 million combat related deaths (killed or died of wounds) and another two to three million military deaths caused by accidents, disease and deaths while prisoners of war. Official government reports listing casualty statistics were published by the United States and Great Britain. These secondary sources published during the 1920s, are the source of the statistics in reference works listing casualties in World War I. This article summarizes the casualty statistics published in the official government reports of the United States and Great Britain as well as France, Italy, Belgium, Germany, Austria and Russia. More recently the research of the Commonwealth War Graves Commission (CWGC) has revised the military casualty statistics of the UK and its allies; they include in their listing of military war dead personnel outside of combat theaters and civilians recruited from Africa, the Middle East and China who provided logistical and service support in combat theaters. The casualties of these support personnel recruited outside of Europe were previously not included with British war dead, however the casualties of the Labour Corps recruited from the British Isles were included in the rolls of British war dead published in 1921. The methodology used by each nation to record and classify casualties was not uniform, a general caveat regarding casualty figures is that they cannot be considered comparable in all cases.
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.