Later known as World War I, this was a globe-spanning war between two distinct factions. The Allied powers, which consisted of France, the United Kingdom, the United States, Italy, Russia, Japan, and others, while the Central Powers, which consisted of Germany, Austria-Hungary, The Ottoman Empire, Bulgaria, and others. This was a war that was centered around the upset of the balance of power in the European nations, with nations such as Austria-Hungary falling out of power. While the war was done over the upset in the balance of power, it was also caused in part by economic factors, with many of the countries competing against each other in the area of industrial strength. And in this area, the Great War featured some of the most pertinent developments towards the advancement of war technology. Things such as the employment of gas weapons and trench warfare characterized the technological developments in the war, things that changed the course of war forever. The Great War only lasted for four years; however it was cited as having one of the largest death tolls of any war in history after the fact, which highlights the potentiality of the dark side in humanity to apply their talents to committing atrocities senselessly. Wartime economy also proved hard for civilian life, the effects of which are highlighted in works of literature of the time.

https://en.wikipedia.org/wiki/World_War_I