The Watcher by the Threshold by John Buchan

Private Peter Galbraith, of the 3rd Lennox Highlanders, awoke with a splitting headache and the consciousness of an intolerable din. At first he thought it was the whistle from the forge, which a year ago had pulled him from his bed when he was a puddler in Motherwell. He scrambled to his feet, and nearly cracked his skull against a low roof. That, and a sound which suggested that the heavens were made of canvas which a giant hand was rending, cleared his wits and recalled him to the disagreeable present. He lit the dottle in his pipe, and began to piece out his whereabouts.

Late the night before, the remnants of his battalion had been brought in from the Gheluvelt trenches to billets in Ypres. That last week he had gone clean off his sleep. He had not been dry for a fortnight, his puttees had rotted away, his greatcoat had disappeared in a mud-hole, and he had had no stomach for what food could be got. He had seen half his battalion die before his eyes, and day and night the shells had burst round him till the place looked like the ironworks at Motherwell on a foggy night. The worst of it was that he had never come to grips with the Boches, which he had long decided was the one pleasure left to him in life. He had got far beyond cursing, though he had once had a talent that way. His mind was as sodden as his body, and his thoughts had been focussed on the penetrating power of a bayonet when directed against a plump Teutonic chest. There had been a German barber in Motherwell called Schultz, and he imagined the enemy as a million Schultzes -- large, round men who talked with the back of their throat.