A disturbed and introverted character, Georg Trakl had already become a drug addict before the war commenced [he trained as a dispensing chemist, perhaps in part to assure access to drugs]

"Late in August 1914, Trakl left for Galicia as a lieutenant in the Medical Corps of the Austrian army. After the battle of Grodek, he was put in charge of ninety serious casualties whom – as a mere dispensing chemist hampered by the shortage of medical supplies – he could do almost nothing to help. One of the wounded shot himself through the head in Trakl's presence. Outside the barn where these casualties were housed, a number of deserters had been hanged on trees. It was more than Trakl could bear. He either threatened or attempted suicide, with the result that he was removed to Cracow for observation as a mental case. His last poems, 'Klage' (Lament) and 'Grodek' were written at this time.
He now feared that he too would be executed as a deserter. According to the medical authorities at Cracow, he was under treatment for dementia praecox (schizophrenia); but the treatment consisted of being locked up in a cell together with another officer suffering from delirium tremens. During this confinement, Ludwig von Ficker visited Trakl and asked Wittgenstein, who was also serving in Poland, to look after Trakl; but Wittgenstein arrived too late. After a few weeks of anguish, Trakl took an overdose of cocaine, of which he died on 3 or 4 November 1914. He was 27 years of age."
[from Michael Hambuger's essay on Georg Trakl in 'The Lost Voices of World War I' an international anthology of writers, poets and playwrights edited by Tim Cross and published by Bloomsbury, 1998 (ISBN 0 7475 4276 7)]

Hamburger also mentions "The family house at Salzburg, with its old furniture, paintings and statuary, as well as the family garden in a different part of the city, contributed images to many of Trakl's poems…"
Below is the Trakl house as it appears today; note the plaque to the right of the sun awning. The place's present incarnation seems to be as a café or restaurant.