Siegfried Sassoon - The Rear-Guard

Groping along the tunnel, step by step,
He winked his prying torch with patching glare
From side to side, and sniffed the unwholesome air.

Tins, boxes, bottles, shapes too vague to know,
A mirror smashed, the mattress from a bed;
And he, exploring fifty feet below
The rosy gloom of battle overhead.
Tripping, he grapped the wall; saw someone lie
Humped at his feet, half-hidden by a rug,
And stooped to give the sleeper's arm a tug.
"I'm looking for headquarters." No reply.
"God blast your neck!" (For days he'd had no sleep.)
"Get up and guide me through this stinking place."
Savage, he kicked a soft, unanswering heap,
And flashed his beam across the livid face
Terribly glaring up, whose eyes yet wore
Agony dying hard ten days before;
And fists of fingers clutched a blackening wound.
Alone he staggered on until he found
Dawn's ghost that filtered down a shafted stair
To the dazed, muttering creatures underground
Who hear the boom of shells in muffled sound.
At last, with sweat of horror in his hair,
He climbed through darkness to the twilight air,
Unloading hell behind him step by step.

Siegfried Sassoon

http://www.poemhunter.com/poem/the-rear-guard/