The poem begins as night is changing into day, dawn "emerging" in a "wild purple...sun." Soon the hill, which is at first covered only in smoke, is covered in tanks which "creep" forward toward battle. The sound of this environment changes as the "barrage" of guns begins to "roar" through the air.
The position of the men changes next; previously hidden in the trenches, they emerge over the top of the dirt and begin climbing toward enemy fire, their bodies "bowed" under the weight of the gear they must carry.
The ending of the poem returns to the idea of time; the men wear watches on their wrists which mark the passing of time as they approach a dangerous and "bristling fire." The men, who likely awaited the start of this day from their position in the trenches, are no longer concerned with time; it is a "blank" and empty concept with no relevance to their current struggle.
In the end, hope itself has changed. The notion has lost its sense of promise in the midst of so much devastation and "flounders in the mud" as the men leave the trenches to face a near certain death.