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 Serbian Army declined severely towards the end of the war, falling from about 420,000 at its peak to about 100,000 at the moment of liberation. The estimates of casualties are various: the Serb sources claim that The Kingdom of Serbia lost more than 1,200,000 inhabitants during the war (both army and civilian losses), which represented over 29% of its overall population and 60% of its male population, while western historians put the number either at 45,000 military deaths and 650,000 civilian deaths or 127,355 military deaths and 82,000 civilian deaths. According to estimates prepared by the Yugoslav government in 1924, Serbia lost 265,164 soldiers, or 25% of all mobilized people. By comparison, France lost 16.8%, Germany 15.4%, Russia 11.5%, and Italy 10.3%.