According to lasdontrailofhonor.com:
The next two busts along the trail are dedicated to the servicemen of the First World War, also known as “the Great War.” The monument features two busts: an infantryman and a pilot, representing the two major fronts of the conflict. World War I was the tragic result of numerous alliances of rival European countries being provoked into war by the assassination of Archduke Franz Ferdinand of Austria-Hungary. The conflict is noted for the evolution of immensely lethal weapon technologies such as poison gas, tanks and new aerial warfare through the use of airplanes. Most of the war was fought from the trenches of France and along the RussianGerman border between the Allied and Central powers. In 1918 American forces entered the conflict and the trenches, and with the aid of these additional troops the Central powers were defeated.