According to "introduction to dark romanticism: american gothic," how do dark romantic writers address the theme of human nature?

You didn't provide the introduction, but Dark Romantic writers often believed that the human soul is corrupt and dark and tends to sin. According to them, no matter how much we try not to, we will eventually succumb to corruption and sin, which was explored by writers such as Poe, Hawthorne, Melville, and similar.

Because the vietnam war was fought in an especially brutal and untraditional way