All Quiet on the Western Front isn't especially replete with symbolism, but there are a number of recurring motifs in the story. Relevant to this particular question is the recurrence of the pressure that patriotism imposes upon young minds. Looked at from a rational standpoint, participating in such a carnival of slaughter seems like the very height of madness. Yet thanks to society's pressure, young men like those depicted in the story are expected to sacrifice their lives for the nation and think nothing of it.
This particular motif is exemplified most strongly in the character of Herr Kantorek, the boys' teacher. He instills them with the fanatical belief that war is glorious, the very life-blood of the nation. Far from teaching his students that war is a terrible, bloody business which involves wholesale slaughter and suffering on a monumental scale, Kantorek makes it sound incredibly heroic and glamorous.
Kantorek's nationalistic speeches are recalled by Paul and his comrades at various stages throughout the book with growing disgust. Their experiences of life on the front line bear no resemblance whatsoever to the romanticized portrait of war presented to them by their teacher. This only serves to make them all the more disillusioned. They realize that they've been lied to by Kantorek and so many other adult authority figures who really ought to have known better.