What one word would you use to describe World War I? Why did you choose that word?

"Devastating." I chose this word because World War I had an immense impact on the world, with millions of people losing their lives, economies ruined, and social and political structures being upended. The war also left a lasting impact on the psyche of the world, with the horrors of trench warfare and the use of modern technology like machine guns and poison gas forever changing the face of warfare. Overall, the devastation caused by World War I is unparalleled in history.