This year is the centenary of the Armistice to end what Siegfried Sassoon called ‘the world’s worst wound’: the first world war. A bare week before the conflict concluded in a grey November, another poet, Sassoon’s friend and protégé Wilfred Owen, whose work now epitomises the waste and futility of that struggle, was cut down by a machine-gun as he tried to lead his men across the Sambre-Oise canal in one of the war’s last battles.