World War One poetry is not a single school of poetry. It is not a neat literary movement with a shared manifesto, a clear doctrine and a friendly group photo. It is more interesting than that. It is a literary crisis.
The First World War forced poets to confront experiences for which inherited poetic language often seemed inadequate. Earlier poetry had represented war through honour, glory, sacrifice, heroism and national destiny. However, the Great War brought industrial killing, trench warfare, artillery, gas, shell shock, mass casualties and a deep crisis of meaning.
This is why World War One poetry is a problematic issue. The poets did not simply write about war. They had to discover whether poetry could still speak truthfully after the battlefield had become mechanised, anonymous and absurd.