Read the excerpt then answer the question: Excerpt from "O Captain! My Captain!" by Walt Whitman

"My Captain does not answer, his lips are pale and still;
My father does not feel my arm, he has no pulse nor will;
The ship is anchor’d safe and sound, its voyage closed and done;
From fearful trip, the victor ship, comes in with object won;
Exult, O shores, and ring, O bells!
But I, with mournful tread,
Walk the deck my Captain lies,
Fallen cold and dead."

In at least 150 words, describe the poetic devices used in this poem.