Iron Maiden’s version of “The Rime of the Ancient Mariner” can be considered as Romantic poetry through the way the song itself is delivered. The instrumental backing the vocals provide a way of a rising and fall of emotion throughout the song. For example, using the video provided to us, starting at about 5:20 there is sudden shift in tone going from a very upbeat tempo to a slow, ominous, elongated instrumental which then becomes the background for a quote from the poem,
One after one, by the star-dogged Moon,
Too quick for groan or sigh,
Each turned his face with a ghastly pang,
And cursed me with his eye.
Four times fifty living men,
(And I heard nor sigh nor groan)
With heavy thump, a lifeless lump,
They dropped down one by one.
The sudden change in dynamic helps add more to the imagery of seeing all of the men die before his eyes. It is also important to note that this piece of the song is in the point of view of the mariner. I would argue choosing to put this particular piece of the song as the mariner remembering also works to further emphasize how the mariner’s tale turns somber as he is telling the sad tale of his journey.