Siegfried Sassoon - Golgotha

Through darkness curves a spume of falling flares
That flood the field with shallow, blanching light.
The huddled sentry stares
On gloom at war with white,
And white receding slow, submerged in gloom.
Guns into mimic thunder burst and boom,
And mirthless laughter rakes the whistling night.
The sentry keeps his watch where no one stirs
But the brown rats, the nimble scavengers.

Siegfried Sassoon

http://www.poemhunter.com/poem/golgotha/