tension and horror

I'm going to say this happens in chapter 4. They arrive at the artillery lines, where the fired guns rattle the ground and make the air taste of gunpowder. The men, though reserves and not in the front-line, become serious. Having been to the front before, they are not fearful, but the new recruits are. Kat predicts there will be a bombardment tonight. The English artillery starts firing--an hour before their regular ten o'clock schedule. Gunfire opens nearby, and again Paul observes a change in the men's faces and behavior. Paul feels the front is like a whirlpool, sucking him in. The earth becomes the soldier's closest ally as he buries himself into it during fighting, seeking holes and small valleys for protection. He believes this action is instinctive, and the only way to save oneself.