In the Beowulf quote, notice the repeated use of the letter "F" in these lines from Beowulf. What tone does the alliteration help convey?
"And Beowulf uttered his final boast: 'I've / never known fear, as a youth I fought / in endless battles, I am old now, / But I will fight again, / seek fame still, If the dragon hiding in his tower dares to face me.' Then he said farewell to his followers." (paraphrase, 44:626)
This quote from the Anglo-Saxon epic poem Beowulf contains consistent alliteration which contributes to the meaning and tone of the quote.
Beowulf has been king for fifty years, and now he prepares to face his final challenge. The dragon has been wreaking havoc, and Beowulf must defeat this marauding foe as he has done several times before. He says:
And Beowulf uttered his final boast: "I've never known fear, as a youth I fought in endless battles, I am old now, But I will fight again, seek fame still, If the dragon hiding in his tower dares to face me." Then he said farewell to his followers.
Beowulf's repeated use of the letter "F" has several effects on tone.
First, this is a letter which is forceful fricative, adding emphasis to the key ideas from the passage: final, fear, fought, fight, fame, face, farewell, followers. Read those words in succession, and you have the entire speech in just a few words. The alliterative "F-words" give the passage a rather aggressive, forceful tone.
Second, the fricative "F" sound slows the otherwise quickly moving b, d and t sounds. This is not surprising, as Beowulf is forceful evne in old age to engage in this battle and save his people. The last two alliterative words are just a bit longer and not surrounded by explosive b, d and t sounds, suggesting a more lingering farewell to his followers. This force mixed with quickness is part of tone, reminding us that though Beowulf is much older now, he is still poised and ready to fight.
For fun, try substituting the alliterative words in this passage with either different words or words all beginning with a different letters (as in "he said goodbye to his guards") and see how the tone changes. It is surprising to realize that such a seemingly small thing changes the entire tone of the passage.