World War I casualties
The total number of deaths includes from 9 to 11 million military personnel. The civilian death toll was about 8 million, including about 6 million due to war-related famine and disease. The Triple Entente (also known as the Allies) lost about 6 million military personnel while the Central Powers lost about 4 million. At least 2 million died from diseases and 6 million went missing, presumed dead. This article lists the casualties of the belligerent powers based on official published sources.
Chemical weapons in World War I
Phosgene was never as notorious in public consciousness as mustard gas, but it killed far more people, about 85% of the 90,000 deaths caused by chemical weapons during World War I.