I, too, saw God through mud,—
The mud that cracked on cheeks when wretches smiled.
War brought more glory to their eyes than blood,
And gave their laughs more glee than shakes a child.
Merry it was to laugh there—
Where death becomes absurd and life absurder.
This is ambiguous. Does it mean that they saw ‘glory’ or their eyes reflected their own inner glory? One assumes the latter. The word ‘glory’ in itself is nebulous, and difficult to apply to such  terrible experiences. The essence, according to the poet, is that the men were uplifted by suffering. We can assume that qualities like selflessness, courage and comradeship emerged in times of great distress, fear and hardship.