Here's ONE example as a model:
In Chapter 4, the men watch the horses ride out carrying ammunition and supplies to the front. Paul comments on how magnificent the horses appear. Later, the men hear an unearthly screaming, and they realize that the screams are not from the soldiers, but from the horses. The front line is being attacked, and the horses have gotten caught in the crossfire. Paul and his company see some horses hobbling around on broken legs and others running with their intestines ripped from their bellies. Detering says, "It is of the vilest baseness to use horses in the war." Detering, who has a love for nature, is reminded by the horses of his farm and his longing to return home. Further, Detering's comment suggests that the horses are innocent creatures who have nothing to do with the war between men; the horses should not have to die horrible deaths in a war that they have not created. On a figurative level, the horses are a symbol of the innocent men who similarly lose their lives fighting a war of which they know and understand little. The horses represent the loss of innocence that comes with the war.