Depends on the poet. The author of the poem "Trees", Joyce Kilmer, died during that war. I think he wrote some war poetry as well.
The poem "In Flanders Fields", by John McRae, hits pretty hard too.
Some went to war to be heroes. Some were drafted. Some didn't want to go at all. Those who hadn't seen war before thought it would be glorious, while the veterans knew it would be horrible. It's a recurring theme throughout history.