David Jones was a London Welsh poet who fought in the First World War with the 38th Division of the 18th Royal Welch Fusiliers, returning with shell-shock to write a huge poem in prose and verse, In Parenthesis – the parentheses being the brackets around the years 1914-1918. Iain Bell has written a moving and powerful opera to a libretto by David Antrobus and Emma Jenkins, based closely on David Jones’ poem, and timed to coincide with the 100th anniversary of the Battle of Mametz Wood which took place on 11-17 July 1916, and at which Jones’s battalion alone lost 263 men. Those missing in action from the Welsh regiments are commemorated outside the Wales Millenium Centre (itself decorated with lettering based on David Jones’s calligraphy) in an art installation called Field.

The first act follows Jones’ alter ego, Private John Ball (Andrew Bidlack), from recruitment to training as an awkward squaddie, to his march from London to Southampton and his sea crossing to France. The parabolic wooden set (an effective vocal amplifier) serves as training camp, ship and trench, and allows the chorus to perform on two or three levels simultaneously, giving an additional dimension to the subtle distinction between the male and female chorus.

What lifts Jones’ poetic vision out of the filth and squalor, violence and indifference of the world of war is his invocation of the old Celtic bards and their poems of ancient battles. The earliest poem in Welsh, Y Gododdin, tells the story of the battle of Catraeth (now Catterick) at which all but the poet were killed. Each section of the poem, and of the opera, is heralded by a quotation from this fragmented epic. A solemn figure in clerical dress is paired at the start with a woman in the formal dress of 1914: these are the Bards of Britannia and Germania, who comment on the action. Sung by Peter Coleman-Wright and Alexandra Deshorties, they bracket the opera in their various guises, reappearing as an officer, a barmaid and the half-woman, half-tree who is the Queen of the Woods, the goddess of Mametz.

Ball’s misadventures climax in his near-destruction by a shell at the end of Act I. By Act II, his battalion is marching towards the Somme, with Mametz Wood as its objective. Other soldiers have made their mark: Privates Watcyn and Wastebottom, Lieutenant Jenkins and Lance-Corporal Lewis. The most vivid of them is Dai Greatcoat, a superb piece of characterisation by Donald Maxwell, who makes this braggadocio figure from the Commedia dell’Arte who has fought in every battle since Michael conquered Lucifer into a sympathetic old soldier, coughing from the pervading wet and cold of the trenches, and always surviving till the next encounter. Maxwell’s characterisation here reminds me of his prisoner in The House of the Dead, also a Pountney production which brought even more strongly to life the horrors of being confined among a mass of other people without hope of release.

Above all in this opera, it is Iain Bell’s writing for chorus that stands out. The male chorus of soldiers sing marches, songs of battle and triumph, and one particularly effective rendering of the Llanelli anthem, Sospan bach. The female chorus sings music that belongs more in Ball’s visionary world, and emerges from his visions. There are some points where this seems to over-sweeten the account of war. Women in a French bar entertain the troops at the start of Act II, led by the Barmaid (Deshorties again), and this is understandable to all, and rooted in reality. But when Deshorties appears again with twigs for fingers and branches for hands as the Queen of the Woods, and her flower-hatted attendants place their hats like wreathes on the bodies of the dead soldiers, it seems that David Jones’ private vision is superimposed on others in a way that they might not have recognised, as if the visionary poet was the rule rather than the unique exception.

Carlo Rizzi conducted the fine score in all its military, lyrical and folkloric colouring with conviction and force, giving the audience at the Wales Millennium Centre a work to contemplate that provoked both grief at the waste of lives, and hope for the rebirth of the wood at Mametz, now a century later green once more.