'The fair breeze blew, the white foam flew,
The furrow followed free' is an example of -

Repetition of consonant sounds at the beginning of words or stressed syllables is known as alliteration.
Example:
“Puffs, powders, patches, Bibles, billet-doux". (Pope: The Rape of the Lock)
Here, ''p'' and ''b'' have been repeated.

Another example:
The fair breeze blew, the white foam flew,
The furrow followed free;
(Coleridge: The Rime of the Ancient Mariner)
Here, "f" and "b" have been repeated.

Source: An ABC of English Literature - Dr M Mofizar Rahman.