This shows that WWI was not really a “world war” as it involved only 16 countries among the 180 there was on Earth. That’s not even 10% … another white colonialist and imperialist vision of the world.
The following is a breakdown of the number of troops that fought, died, and were wounded in World War I, as recorded in Michael Clodfelter’s Warfare and Armed Conflicts: A Statistical Reference to Casualty and other Figures. The number of civilians killed have been counted as well. This article is only a quick analysis of man power in the first World War. It does not cover other important logistics such as supplies, funding, etc.
In the long run, the Central Powers had nearly half the amount of troops fight in World War I. When Russia exited the war in 1917, the Central Powers fought on more even ground and in some arenas had the numerical advantage, but troops trickling in from America would change this scenario in the end.