I knew a simple soldier boy
Who grinned at life in empty joy.
Here, Sassoon introduces the soldier. He is depicted as a happy and positive person who is also perhaps a little young and naive. The description of his joy as "empty" suggests that he has not experienced much of the world and is eager for adventure. This heightens the tragedy of his later suicide and erasure from public memory. The soldier's simplicity shows that he is like any of the millions of men (and thousands of underage boys) that enlisted and fought in the First World War.
Slept soundly through the lonesome dark,
And whistled early with the lark
The speaker further describes the soldier, telling us that he wasn't someone who was easily troubled. Before his traumatic experiences during the war, he slept soundly through the night and was up early, ready to enjoy the day. The speaker has his own perception of the world that differs from this innocent young man's, shown by the characterization of the dark as "lonesome" (Line 3). Unaware of the sadness that exists in the world, the young soldier experiences a peaceful life in connection with nature.
In winter trenches, cowed and glum,
With crumps and lice and lack of rum,
He put a bullet through his brain
No one spoke of him again.
In the second stanza, the event occurs which gives the poem its name. The abruptness with which the soldier's suicide is conveyed is meant to shock to the reader. Just three lines previously, the poet focused on how happy and untroubled the soldier was before he went to war.
Overall, Sassoon shows how traumatic the experience of war was, transforming many soldiers into unrecognizable people. In extreme cases, the soldiers who could not cope committed suicide. This emphasizes the tragic consequences of war which military officials and the general public did not want to deal with.
