All Quiet on the Western Front
Broadly, the enemy here is ignorance.
In All Quiet on the Western Front, ignorance is put on steroids when it is coupled with unearned power, especially that of title, uniform, and social "place." That enemy is represented by disingenuous or irresponsibly idealistic school teachers who are overly sure of themselves, by politicos in high places who ordered this war, and by ordinary people who want to assume high power inside of a military uniform. Amazingly, the enemy is never painted as the French, the Russians, the British, or the Americans who are actively trying to kill Paul – his enemies are all from within.