The function of alliteration in poetry is to provide an alternative rhythm or meter to the poem. It provides another option for the poet when considering how he or she should compose the latest poem. Other options include changing meter, rhyming and free verse. Alliteration has a rich tradition in English and formed the bedrock of pre-1066 English poetic forms. Alliteration does not affect the theme or content of the poem.
Alliteration is the repetition of the first stressed sound of a word. This often appears as successive words starting with the same letter, however, not all letters are pronounced the same way and true alliteration replicates the stressed syllable. Sometimes the stressed syllable will be the second or third syllable of the word, but is rarely, if never, the final syllable.
The sequencing of words with repeated syllables provides both structure and rhythm. Alliteration in poetry has both a visual and an aural function. The repeated sounds allow the syllable to amplify as each word is pronounced. This is used to emphasize the beauty of the language being used.
In terms of structure, alliteration used in poetry is far from free verse. Alliterative verse in Old English had a specific structure to it. Each line was divided into two half lines; the first half line contained two alliterative syllables and the second half line one. The final stressed syllable of the line, to make a total of four, would be unrelated phonologically to the previous three. A segment of “Beowulf,” a famous Old English poem, can be used to demonstrate this:
“oft Scyld Scefing sceaþena þreatum,
monegum mægþum meodosetla ofteah,
egsode eorlas, syððanærest wearð
feasceaft funden; he þæs frofre gebad,
weox under wolcnum weorðmyndum þah”
The rhythmic function of alliteration in poetry becomes obvious when the poem is read aloud. The visual function can also be glimpsed by looking at the repeated letters. Alliteration is shown by repeated elements such as “scyld scefing sceathena” and “monegum maegthum meodosetla.” As the translation proves, the function of alliteration is harder to reproduce in modern English:
“Oft Scyld the Scefing from squadroned foes,
from many a tribe, the mead-bench tore,
awing the earls. Since erst he lay
friendless, a foundling, fate repaid him:
for he waxed under welkin, in wealth he throve”
In English, the final two lines best show the function of alliteration in poetry. The function has become more difficult because the nature of English poetry changed for many reasons after the Norman conquest of 1066. First, the language itself has developed and diversified, so that now it is simply harder to use modern vocabulary to produce alliterative verse. Secondly, poetic styles changed from alliteration to forms such as iambic pentameter and rhyming endings under the influence of medieval French poetry.