Alliteration dramatizes the poem's images, bringing them to vivid life on the page.
In line 17, for instance, the speaker describes the "stroller's stride" with which the young Sarajevans walk. The two /st/ sounds one after the other mimic the confident one-two "stride" of these courageous kids, who go out to flirt in spite of the danger.
Meanwhile, in the fourth stanza, the speaker switches focus from the young lovers to the aftermath of a terrible mortar attack:
[...] they stand
on two shell splash scars, where, in '92
Serb mortars massacred the breadshop queue
and blood-dunked crusts of shredded bread
lay on this pavement with the broken dead.
This intense alliterative burst of harsh /s/ sounds, plosive /b/ sounds, and muffled /m/ sounds conveys violence, surprise, and chaos, evoking the shock and misery of this "massacre."
In the same stanza, the speaker mentions "the Sarajevo star-filled evening sky/ ideally bright and clear for bomber's eye" (lines 37-38). Here, alliteration underlines the tension the young lovers live with: the /s/ sound feels whispery and hypnotic, like some kind of love spell being cast over the city—but it also sounds like bullets whistling through the air. And the /b/ sounds again feel shocking and explosive, just like the bombs that "bomber" might drop at any moment.
And the young couple stands by "death-deep, death-dark wells" (line 41), the /d/ alliteration sounding powerful and relentless, as though the city has been permanently changed by what it has witnessed.
When the young couple goes for a coffee, the poem uses a few more moments of alliteration:
The dark boy shape leads dark girl shape away
to share one coffee in a candlelit café
until the curfew, and he holds her hand
behind AID flour sacks refilled with sand.
The /c/ sound here could be read as quiet and intimate, but it's also a little harsh and cutting, perhaps signalling that, for all the young couple's attempt to have a normal date, this is a deeply strange situation. And the /h/ sounds might feel either like a loving sigh or a gasp of fear.
Alliteration thus makes the Sarajevans' predicament feel vivid and immediate.