The first stanza of “Success is Counted Sweetest” makes frequent use of alliteration, which, combined with sibilance and consonance, makes its moral message all the more memorable. This stanza is filled with repeated /s/ and /n/ sounds at the start of words.
The poem here is building a metaphor, mapping the idea of “success” onto taste (specifically, onto sweetness). The “sweet” taste of success is one best enjoyed—or one that would be best enjoyed—by those for whom it is most unattainable.
The next instance of alliteration is between “ne’er” and “nectar” (lines 2 and 3). These words look and sound very similar, with just the /ct/ added or taken away to make them sound the same. This places the two concepts close together: “ne’er,” which represents denial and failure, with “nectar,” which stands in for the sweet taste of success. This creates a “so-near-yet-so-far” effect, with “nectar” placed tantalizingly—but forever—out of reach. This then widens to include the “need” of line 4.
The other example of alliteration in “Success is Counted Sweetest” comes in line 9. Here, the two /d/ sounds of “defeated” and “dying” combine with caesura to create a sense of weariness and small, difficult movement in keeping with the description of a dying soldier. Indeed, the first and last syllables of “defeated” even create the word “dead.”
This alliteration also chimes with the /d/ in “distant,” which has a similar effect to the /n/ alliteration discussed in the paragraph above. The alliteration helps draw a distinction between the “dead” soldier in one place and the victorious “distant” army in another, showing that they are close in the sense that there are fine margins between victory and defeat but also far apart in terms of what it means to succeed or fail.