It is very interesting to examine the way that conflict is presented in this excellent poem based on the horrors of World War I. I would argue that there are three different kinds of conflict in this poem. Let us first start off with the physical conflict that being in a war involves. The soldiers that are limping away from the "haunting flares" of the battlefield and are slowly making their way towards the "distant rest" that awaits them. However, even though they are retreating they are not safe, as the gas attack shows. This physical conflict is therefore perhaps the most important type of conflict that there is.
However, at the same time, let us not be blind to the way that the speaker himself is subject to an emotional conflict, as the images of what he experienced as a soldier haunt him every single night:
In all my dreams, before my helpless sight,
He plunges at me, guttering, choking, drowning.
The way in which the speaker cannot escape this terrible images shows the emotional conflict that he suffers as he tries to live his life but is unable to move on from this experience. This is a conflict that psychologically, the speaker pushes on to his audience at the end of the poem. Note how this is reinforced by the change of tense, as suddenly the speaker addresses us by saying "If you...", involving us in the horror and tragedy of war and causing us to question our beliefs about war and conflict. This is not a poem to be read and enjoyed from the comfort of our armchairs. We are placed in a position of psychological conflict too.