This poem was written by a young soilder in the first world war called Wilfred Owen. Wilfred Owen suffered from shell shock during the war and this is thought that this poem was written during 1917 during his time in a hospital after a number of incidents that left him suffering with neurasthenia.
Owen enlisted in the Artists' Rifles Officers' Training Corps. On 4 June 1916 he was commissioned as a second lieutenant in the Manchester Regiment.
He fell into a shell hole and suffered concussion, he was blown high into the air by a trench mortar, and spent several days lying out on an embankment in Savy Wood amongst (or so he thought) the remains of a fellow officer. Soon afterwards, Owen was diagnosed as suffering from neurasthenia or shell shock and sent to Craiglockhart War Hospital in Edinburgh for treatment. It was while recuperating at Craiglockhart that he met fellow poet Siegfried Sassoon, an encounter that was to transform Owen's life.
Wikipedia
Owen was killed in action during a crossing of the Sambre–Oise Canal on the 4th November 1918, aged 25.