Graphic
Blood
Gore
Character is brutally stabbed
People are shot and stabbed loads of times
Early on, we see a field of battle littered with dead horses and men. Topthorn gets pretty beaten up and broken down toward the end of the war, and Joey tears himself up something awful when he runs through the fields full of barbed wire. (He runs so fast that their tangles cause him to flip over, landing hard and painfully.) He is partially covered in blood. Characters frequently point guns at horses, preparing to shoot them, and we hear guns fired that apparently slaughter other horses.
Men suffer as well. We see many die in the course of the story, including two who are shot for deserting. Bodies go flying during explosions. Others are mowed down by rifle or machine gun fire. One soldier is told to stay behind and shoot anyone who retreats back to his home trench. One man gets wounded in the leg. Others are gassed. We see people who are missing limbs and have their eyes bandaged. Violence is relatively bloodless, but we see wounds with blood on them.
Albert is thrown from Joey over a fence. Someone's knocked down by a horse. We learn that Emilie's parents died in the war.