Civilian casualty ratio
Some 7 million combatants on both sides are estimated to have died during World War I, along with an estimated 10 million non-combatants, including 6.6 million civilians. The civilian casualty ratio in this estimate would be about 59%. Boris Urlanis notes a lack of data on civilian losses in the Ottoman Empire, but estimates 8.6 million military killed and dead and 6 million civilians killed and dead in the other warring countries. The civilian casualty ratio in this estimate would be about 42%. Most of the civilian fatalities were due to famine, typhus, or Spanish flu rather than combat action. The relatively low ratio of civilian casualties in this war is due to the fact that the front lines on the main battlefront, the Western Front, were static for most of the war, so that civilians were able to avoid the combat zones.
Serbian Campaign of World War I
The Serb sources claim that the Kingdom of Serbia lost 1,100,000 inhabitants during the war. Of 4.5 million people, there were 275,000 military deaths and 450,000 among the ordinary citizenry. The civilian deaths were attributable mainly to food shortages and the effects of epidemics such as Spanish flu. In the addition to the military deaths, there were 133,148 wounded. According to the Yugoslav government in 1924, Serbia lost 365,164 soldiers, or 26% of all mobilized personnel, while France suffered 16.8%, Germany 15.4%, Russia 11.5%, and Italy 10.3%.