The finest commemoration of the First World War centenary I've seen to-date, this deserves a much longer life.' Dominic Cavendish, Daily TelegraphMametz by Owen Sheers was premiered by National Theatre Wales in June 2014.

"For years afterwards the farmers found them - the wasted young, turning up under their plough blades." So run the blunt, grimly beautiful opening lines of the Welsh poet Owen Sheers's elegy for the men, 4,000 of them from the 38th (Welsh) Division, who were killed or wounded in the Battle of Mametz Wood in July 1916, among the many costly attacks that took place in the First Battle of the Somme. Sheers revisits that chapter of carnage in a stirring, sprawling promenade show. Among the many questions Mametz leaves you pondering is whether you need to go to some corner of a foreign field to commemorate the Great War dead or can pay tribute by looking at the landscape they never returned to. Furthermore, incorporating references to Einstein's emerging theory of relativity, an advance for mankind just as it was going backwards, it throws what we think of as "the past" into doubt. The piece begins as a parody of a battlefield experience tour, with a brolly-wielding professor talking loudly and taking the assembled hordes through a mock-up support trench, as gunfire booms in the distance. Two hours later, we end up in dark woods and a place of numb desolation, bombarded by words that pierce the heart and vignettes that capture the stomach-churning sacrifice. Along with imagined exchanges in a recreated trench and poignant letters home, Sheers draws on the writings of two survivors in particular. One is the poet David Jones, whose fractured, enervated, modernist response to his war-time experiences, In Parenthesis (1937), was hailed as a "work of genius" by TS Eliot. The other key influence is the writer Llewelyn Wyn Griffith,. driven to wondering how the sun "could shine on this mad cruelty and on the quiet peace of an upland tarn near Snowdon", as if time itself has been wounded. Poetry and science collide at this point: you see what he means, you feel it in your bones too. The finest commemoration of the First World War centenary I've seen to-date, this deserves a much longer life.