Remarque has a way early on of establishing another theme re: a soldier's life in wartime: how the routines of war dehumanize a soldier in ordinary ways. Baumer, the narrator, talks about how one quickly loses one's sense of civilized human dignity when it comes to something as simple as voiding one's bowels. Baumer writes about how all the soldiers having to use the latrine to defecate together. They quickly get used to it. "The soldier is on friendlier terms than other men with his stomach and intestines," Baumer says.
"Three-quarters of his vocabulary is derived from these regions, and they give an intimate flavour to experessions of his greatest joy as well as of his deepest indignation. It is impossible to express oneself in any other way so clearly and pithily. Our families and our teachers will be shocked when we go home, but here it is the universal language."
Notice how in this passage and elsewhere in this first chapter Remarque -- who, as we know, served in the trenches during the war -- sets apart the fighting men from the people back home. The soldiers have had their humanity stripped from them, not only from the profound experience of killing and dying, but in quotidian ways. The war is barbarizing them, and observe how the narrator Baumer is already conscious of how different he now is from the folks back home, on whose behalf he is fighting.