The challenge for anyone writing war poetry today is how to avoid sounding like a tribute act doing the Greatest Hits of 1914-1918 with smart bombs and modern line breaks. In his powerful new verse drama Pink Mist, Owen Sheers succeeds in this magnificently.

The poem tells the story of three school friends from Bristol who join the army and fight in Afghanistan. Much of it focuses on what happens after they return – one of them a double amputee, one mentally ill and the third killed by a roadside bomb. The three friends speak the majority of the poem’s lines, interspersed with sections from one boy’s mother and the others’ girlfriends.

The language is clean and unforced. Sheers is a natural dramatist who never gives a character a line they wouldn’t credibly say. The moments when the colloquial diction intensifies to high poetry are as smooth and plausible as when it blurs into military jargon. In the space of a few pages the same character can shift from “Aw, shut it, Arthur!” to “my company were moved to a checkpoint / a mile from the FOB” to “An outdoor man, skin leathered by the sun. / The way he unwrapped the end of his turban / to wipe at his eyes, raw with what we’d done.”

Sheers appropriates military language with a particular skill. Army jargon is something any writer should approach with caution for fear of sounding like one of those potbellied bores who fantasize about being in the SAS. Most thriller writers get it wrong. Almost all poets get it wrong. Sheers gets it right – primarily because he understands that authenticity doesn’t come from piling up technical detail but from making characters speak congruently. So when the teenage protagonists put on acronyms and slang like the whole armour of nervous maturity, the awkwardness of their language resonates perfectly; and when they forget themselves in the adrenaline of battle, the soldier-speak becomes integrated and stops drawing attention to itself.

In a beautiful fusion of jargon, poetry and dramatic skill, Sheers gives Taff’s girlfriend Lisa the passage that explains the book’s title and that deserves to be quoted in full. (A page or so earlier, Taff has told us that “Blue on blue” is used in place of “friendly fire”, the latter no longer being euphemistic enough.)

Pink mist. That’s what they call it.
When one of your mates has just bought it,
but goes in a flash, from being there to not.
A direct hit. An IED. An RPG stuck in the gut.
However it happens you open your eyes
and that’s all they are.
A fine spray of pink, a delicate mist,
as if some genie has granted a wish.
There, and then not.
A dirty trick you pray isn’t true.
White heat. Code red. Pink mist.
Blue on blue on blue.

Underneath this surface story of modern war Sheers has interwoven structural elements from the medieval Welsh poem Y Gododdin – a bardic account of tribal slaughter that reads at times like an earlier and more Celtic Battle of Maldon and at others like a cooled lump from the molten ur-myth of the British Isles. The poem’s Catraeth is commonly identified as modern-day Catterick, where a barracks now provides basic training for new recruits. This allows Sheers to pivot a range of connotations around Y Gododdin’s repeated line “Men went to Catterick with the dawn”. In the medieval poem the battle is immediate and the men’s lives shortened by their consumption of mead (though recent scholarship rejects the idea that they went to battle drunk, reading this figuratively as the warriors’ acceptance of their lord’s gifts in return for fatal service).

Fast forward nearly fourteen centuries and Sheers’s poem opens “Three boys went to Catterick”. The dawn and Catterick are still there, but the men have become boys and the mead has become “a couple of cans” – though later there are echoes of the symbolism of Y Gododdin’s mead when Arthur persuades the others to enlist for their own fatal service “on our fourth or fifth cider”.

Y Gododdin is structured as a series of elegies for those killed in the battle. This was part of the deal for iron age warriors: get brutally but gloriously butchered, and the poet will remember you in his after-dinner verses. Sheers has turned the proposition on its head with a series of elegies that celebrate and mourn the humanity of the young soldiers while refusing to glorify what happened to them. At the same time he avoids easy moralizing, allowing both complexity and pity to arise from the spaces between the different voices.

By building his poem on a 7th century original, Sheers also reminds us that war poetry is older than recorded literature and certainly didn’t begin in 1914. “That’s how it was the morning when / the three of us did what boys always have. / And left our homes for war.” Sheers has no need to escape from the shade of Wilfred Owen because he’s already summoned something older and colder from the medieval mists.

This is a powerful, harrowing book. Poetry lovers should read it; schoolchildren should read it; soldiers and their political masters should read it. And please, BBC Radio 4, can you make March’s radio performance available on iPlayer radio so all of us can hear this urgent and beautiful poem?

Pink Mist, Owen Sheers, Faber, 2013