That Ivor Gurney was a victim of World War I, although he lived nearly two decades beyond the war's conclusion, was a fiction generated by the press releases that appeared at his death.
Gurney actually suffered from bipolar disorder. His condition was not worsened by the War, but rather by the pressures that he encountered after his service of trying to succeed as a composer and poet, which rendered him increasingly emotionally and physically unstable for the rest of his life. He'd gotten off to a good start studying composition with Charles Stanford at the Royal College of Music, an education pursued before and after the war. He also wrote poetry, publishing two war volumes, Severn and Somme and War's Embers. He wrote both poetry and music -- mainly songs -- feverishly between 1919 and 1922. Gurney quickly burned out, though, and spent much of the rest of his life in mental institutions, dying of tuberculosis in 1937. His music, most of which was left in manuscripts of varying salvageability, adhered to Romantic traditions, with rather clotted piano parts but tender melodic lines, and a distaste for word-by-word musical illustration.