Final answer:
Paul Baumer experiences a moment of existential dread in the novel when the certainty of defeat overwhelms him and his fellow soldiers. The thought of their heroic army being beaten fills them with horror and terror.
Step-by-step explanation:
In the novel, Paul Baumer experiences a moment of existential dread when the certainty of defeat comes to him and his fellow soldiers. The thought of their heroic army being beaten by unseen powers such as hunger and death fills them with horror and terror. This moment is portrayed vividly through Baumer's description of the demoralization, panic, and delusion that they face.