In the lines 417 to 421, the word f is alliterated several times in the verse written in <u>iambic pentameter</u> giving it a rhyming feet and allowing the words with f to stand out as important in the lines.
The words that alliterate are
fens
forth
feathered
fledged
<u>The words do not have to be adjacent to each other spatially but metrically which these words do, albeit not being next to each other. Hence they are in alliteration.</u>
