Meyrink did not fight in the Great War; he was 46 when it started. But it certainly did affect his life.
In December 1916 his collection of short stories, Des deutschen Spießers Wunderhorn, was banned by decree of the Royal-Imperial District Court in Vienna. He was critical of Austrian institutions; he was not sufficiently patriotic. A pamphlet by Albert Zimmerman, “an ass from Hamberg”, as Meyrink called him, made it clear:
Meyrink’s attitude is not internationalist, but anti-nationalist. All expressions of nationalism are an abomination to him. He attacks all the nation’s endeavours with his characteristic ruthlessness and the favourite objects of his ridicule are the established representatives of our state and nation (quoted Mitchell, Vivo, 156-157).
The main objection for Zimmerman, however, was that Meyrink was born a Meyer, and (although that was a common German name) was therefore Jewish. In 1925, a Nazi history of German literature said that Meyrink had denied that he was Jewish, “however, from his literary physiognomy and the slant of his writings he is Jewish” (quoted Mitchell, Vivo, 159). Meyrink’s own local paper, the Starnberger Zeitung, attacked him in June 1917 for attacking German women.
Meyrink’s Golem is set in the Prague ghetto; he himself is a Jew. What would people say if, for example, a Catholic should write such offensive things about Protestant pastors’ wives? (quoted Mitchell, Vivo, 159).
Meyrink said that he and his family were refused service in some local shops; navvies threw stones at him as he walked by.
Although Meyrink was against the war, he was incensed by the way in which Allied propagandists portrayed the Germans and Austrians as “barbarians”. He even seems to have done h s bit for the war-effort, apparently offering the authorities novel which showed how Freemasons in France and Britain had been behind the declaration of war in 1914. Another project which Meyrink seems to have been involved in was to counter British propaganda through humour and satire.
Meyrink even had his own occult or spiritual explanation of the benefits of war: in notes for a novel, he wrote (quoted by Mitchell, Vivo, 182):
Anyone who is sensitive and still open to spiritual development could, during the time of the great war, distantly feel powerful new forces flowing into them. They came from the many dying soldiers. Just as the buds on a tree start to sprout vigorously when the gardener prunes the branches. The world of living beings is a large tree; most are only conscious of themselves as a single leaf, but a few make the leap into the wider consciousness of the tree and it is those who do not die, the others fall, sooner or later, like withered leaves. Thus we, who drew in new forces during the time of the great war, are heir to the life of those dead warriors.
My information comes entirely from Mike Mitchell, Vivo: The Life of Gustav Meyrink (Sawtry, Cambs: Dedalus, 2008.