DAILY LIFE DURING WORLD WAR I, Neil M. Heyman, The Greenwood Press, 2002.
Sample casualty figures in WWI:
p. 235 "The four countries together [France, Germany, Great Britain, and the United States] lost a total of approximately 4.25 million men."
Final overseas death toll for US was 76-83,000, of which about 50,000 died from wounds or results of wounds. Rest were disease, mostly Flu. Counting soldiers who never went overseas, total dead about 112,000 (there was a lot of Flu in the training camps).
p. 236 Germany lost between 1.7 and 2 million men.
"Ninety percent of the men in the small expeditionary force of five divisions Britain sent to the Continent in 1914 were casualties by the close of the year…The entering class at Oxford in 1913 lost 31 percent of its members."
p. 237 "One French lycee…lost 26 out of 27 members of its senior class by Christmas 1914. Only the one class member excused from military service due to illness remained alive."
p. 238 "…officers always lost a greater percentage of their numbers than did the enlisted men." "The task of junior officers--to led men into battle--explained the disparity. As the first to climb from the shelter of a trench and the first to cross no man's land, such young men were in deadly peril. Thus, 96 percent of the officers who died in the German army were captains or lieutenants."