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.
Prisoner of war
During World War I, about eight million men surrendered and were held in POW camps until the war ended. All nations pledged to follow the Hague rules on fair treatment of prisoners of war, and in general the POWs had a much higher survival rate than their peers who were not captured. Individual surrenders were uncommon; usually a large unit surrendered all its men. At Tannenberg 92,000 Russians surrendered during the battle. When the besieged garrison of Kaunas surrendered in 1915, 20,000 Russians became prisoners. Over half the Russian losses were prisoners as a proportion of those captured, wounded or killed. About 3.3 million men became prisoners.